Sciencemadness Discussion Board

Flash powder detonation

prometheus1970 - 16-10-2010 at 13:02

\I've been wondering... obviously, flash powder can go boom!, but is what happens to create that boom actually a detonation per se? My impression of what constitutes a detonation is a virtually instantaneous dissociation of a compound at the molecular level. Since there are no flash powder "molecules"(just metal molecules loosely interspersed with oxidizer mkolecules) I wonder if "flash powder detonation isn't just another misnomer of ignorance by the youtube kewl crowd.
For that matter I'm not clear on what makes flsh powder go boom! when confined, if it produces no (or almost no) gases whatsoever. Perhaps it is just the rapid heating of air in the mixture as the aluminum particles deflagate at several thousand degrees fahrenheit... I've seen what black powder, rcandy, matchheads, etc. do when ignited in confinement described as detonation. Apparently what many people think is that if it goes bang, it's a detonation. Overinflated baloons, blown tires, falling books, must all detonate, right? I defer to those who know to supplement my knowledge..::D

The WiZard is In - 16-10-2010 at 15:37

Quote: Originally posted by prometheus1970  
\I've been wondering... obviously, flash powder can go boom!, but is what happens to create that boom actually a detonation per se? My impression of what constitutes a detonation is a virtually instantaneous dissociation of a compound at the molecular level. Since there are no flash powder "molecules"(just metal molecules loosely interspersed with oxidizer mkolecules) I wonder if "flash powder detonation isn't just another misnomer of ignorance by the youtube kewl crowd.

For that matter I'm not clear on what makes flsh powder go boom! when confined, if it produces no (or almost no) gases whatsoever. Perhaps it is just the rapid heating of air in the mixture as the aluminum particles deflagate at several thousand degrees fahrenheit... I've seen what black powder, rcandy, matchheads, etc. do when ignited in confinement described as detonation. Apparently what many people think is that if it goes bang, it's a detonation. Overinflated baloons, blown tires, falling books, must all detonate, right? I defer to those who know to supplement my knowledge..::D



In the middle ages they debated how many angles could dance
on the head of a pin... in the 21st century we try to define
"detonation." If you accept the minimalist definition - burning
faster then the speed of sound in the whatever.... the problem
being determining the speed of sound in a powder.

THE COMBUSTION OF A GRANULAR MIXTURE OF POTASSIUM PERCHLORATE AND ALUMINUM CONSIDERED AS EITHER A
DEFLAGRATION OF A DETONATION
HERSHKOWITZ, JOSEPH
PICATINNY ARSENAL DOVER NJ FELTMAN RESEARCH LABS
74 page(s)
AD0296417
1 JAN 1963

www.DTIC.mil


Report is mostly a mathematically rigorous determination of the
speed of sound in la mixture. You can skip to the JH's conclusion.

I define the difference between deflagration and detonation
on a practical basis... Def - big pieces - Det - small pieces.

At no extra charge I add the following. Not the best thing I have
ever written - but it serves. Most of the refs can be had at
good-old dtic.mil.


Hazards from Salute/Flash/Star Compositions A brief literature survey.
By donald j haarmann aka The WiZ
Scanned in from: The PGII Bulletin No. 65. May 1989 because I lost la file years ago.
Parts that gagged the scanner and a few others have been deleted.

A Compilation Of Hazard and Test Data For Pyrotechnic Compositions. F. L.
Mclntyre, Report ARLCD-TR-80047, October 1980, NTIS AD 096248. 390 pages.

"This report is a compilation of parametric, stability, sensitivity and output data
on selected pyrotechnic compositions derived from hazards evaluation and
classification testing. This report provides a readily accessible source of data for
some 180 pyrotechnic compositions."

"An accident survey was conducted to identify primary hazards and cause/effect
relationships associated with pyrotechnic operations during development,
manufacturing, transportation and thermally ultimate use. "There were 18%
[103] explosions and 5% [27] accidents that transition from either a fire to an
explosion or multiple explosions. As expected, the majority of the incidents
were fires.

The Significant factor here is that 23% of the incidents RESULTED IN SOME
FORM OF AN EXPLOSION, since pyrotechnic compositions are not normally
considered to be explosive in nature." [Emphasis added.] Of interest were the
TNT equivalence (Hi Explosive equivalence) tests. Of the six compositions used
for producing sound two were tested for TNT Equivalence with the following
results: Air Blast Simulator Mixture, as used in the M74A1 and M74 Simulator.
[Aluminum flake 9%, Black Powder 91%] TNT Equivalence was found to be
45%. Detonation Simulator Mixture, use: the infamous M80. [************] TNT
equivalence 80%. It should be noted that; "The M80 fire cracker mixture is no
longer manufactured but is reported along with the test data BECAUSE OF
SEVERAL CATASTROPHIC ACCIDENTS THAT HAVE OCCURRED." [Emphasis
added.]

"Critical Height" and "Critical Diameter" were also measured. "In the critical
height test the "Critical height to explosion data are reported as the greatest
material height in a given container diameter which did not result in transition
from burning to an" explosion.

Critical diameter tests the sample material using C4 as an explosive donor, to
determine the minimum diameter required to induce a explosive reaction.

The critical Diameter for the M80 composition was found to be 0.01 meters [4
inches!!!]. and the Critical Height was measured as being 3.96cm. [1.5 inches!!!]
[Fools rush in where angles fear to tread.]Of the photoflash mixtures tested, TNT
Equivalence of: 30-36-50% were measured. And even closer to homer a Yellow
Star Mixture [Magnesium 18%, Barium Nitrate 17%, Strontium Nitrate 16%,
Potassium Perchlorate 17%, Sodium Oxalate 17%, and HCB 12%] when tested:

"indicated that this mix would detonate and an explosive equivalence (as
compared to TNT) was greater then 50% in a contained vessel ***" This mixture
was also found to be sensitive to friction and impact.

Propagation Rates In Thermally Ignited Pyrotechnic Compositions. Richard W.
Collett, Tech Report ARLCD-TR-77049, August 1978, NTIS ADA060809.

"Work was performed to determine the propagation rates in loose, granular
confined pyrotechnic compositions when initiated thermally. Representative
materials included flash, igniter and flare compositions."All compositions were
tested confined in steel pipe 48" long by 2"id. both ends of which were sealed
with heavy end caps. An igniter pack placed in the bottom of the column was
used for thermal ignition.Conclusions: "All of the compositions tested developed
fast reactions which could cause explosions and be extremely hazardous ***.
The reactions are therefore all classed as detonative." [Emphasis added.]

Of the four basic compositions tested, PFP-555 [Aluminum 15u 40.0%, Barium
nitrate 140u 30.0%, and Potassium perchlorate 20u 30.0%] "can develop either
a low-velocity or high-velocity detonation when thermally ignited. Test 1- 920
meters/sec. Test 2-546 meters/sec."

Explosive Power of Pyrotechnic Compositions. 1.M. Jenkins, Et. All, 19th
Explosives Safety Seminar, Calif. 1980 Page 77 &ff.

"Various pyrotechnic compositions were assessed in three experiments:

1-To measure and assess the explosive power from various initiating stimuli.

2-To measure the explosive power expressed in terms of the equivalent mass of
TNT per unit mass.

3-The likelihood and effect of sympathetic initiation in a practical storage
situation."

Three initiating stimuli were used: 1/fuzehead 2/electric detonator, and 3/a
detonator boosted with a tetryl pellet. The composition being placed in a paper
mache pot, with the initiator being placed at the geometric center of the charge
mass.

Composition #11: Photoflash [40/60 Aluminum/Potassium Percolate] when
ignited by source number three, resulted in an "equivalent mass approximation
kg. TNT per unit mass" of 0.42. More rigorous testing using piezo-electric
pressure transducers to measure air blast and other experiments using foil
gauges raised the TNT equivalence to 50%.

TNT Equivalencies of Black Powder. Volume 1: Management Summary and
Technical Discussion, H.S. Napadensk and J.J. Swatosh Jr., lTIRJ6265-3,
Sept. 1972, NTIS ADA-044444. 69 pages + vii.

"Black powder charges ranging in weight from 8 to 150 pounds were evaluated
under different levels of confinement. The TNT equivalence for the final product
were found to range between zero to 43% for impulse and zero to 24% for
pressure, depending upon the level of confinement, the weight of explosive and
booster, and the distance form the explosion."

The generally quoted figure for the detonation velocity of BP is 400 meters/sec.
However A.F. Belyaev and RKh. Kurbangalina; Russ. J. Phys.Chem. 38:309-
310,1964, as quoted in the LLNL Explosives Handbook, URCL-52997, provide
the following figures Density g/cm3 appx. 0.7, det velocity appx. 1.3 km/cm3,
1.35 km/sec.

Hazards Testing of Ammonium Perchlorate. F.L. McIntyre, et al, 58 pages. NTIS
ADA-114966

A series of hazard classification tests were conducted on ammonium
perchlorate, nominal 200 micron size, packed in 30 gallon, 20 Ga. steel drums
with bolted ring closures, each container containing approximately 250 lbs. of
material.

Tests using a S94 squib and 2 oz. of FFF black powder resulted in NO explosion,
NO over pressure detected, and NO rupture, splitting, or fragmenting of the
drums.

A second series of tests using a number 8 blasting cap produced the same
results. Thermally decomposition, with NO evidence of an explosion.

It would be well to remember however that Ammonium perchlorate in particle
size below 15 micron is considered to be an explosive material under 18 U.S.C.
Chapter 40. And that it can be sensitized with reducing agents.

PATR 2700 provides the following detonation velocities for Ammonium
perchlorate: (Original reference: RH. Richardson, Hazards Evaluation of the Cast
Double-Based Manufacturing Process, ABL/X-47 (1960) AD 250858. [Not seen
by me.]

Dry 400 m/s Wet-ethyl alcohol Wet-acetone 4200 m/s 4500 m/sec.

Studies on Fireworks compositions. 1: Combustion or explosion of crackers and
bursting compositions. Noboru Ishikawa and Masao Kusakabe. "Kogyo Kayaku"
1976,37(6)310-15. [In Japanese] As almost all of this is in Japanese, only the
English summery is available for inspection:

"Crackers always detonated in spite of their small quantities or weak initiation
with igniters.

"Reaction of bursting compositions was always initiated as combustion and
accelerated to detonation in the case of sufficiently large amounts of the charge.

"It was shown that the busting composition with potassium perchlorate was
safer than those with potassium chlorate."

The following compositions were tested:

>Deleted<

Studies on Fireworks Compositions. (11) Combustion Characteristics of Piled
Fireworks Compositions: Gerbs, Star Grains and Star Composition as Powder;
Noboru Ishikawa and Masao Kusakabe. "Kogyo Kayaku" 1979, 40(4), 277-82 (In
Japanese)

This paper reports on work performed by the Japanese government some six
years ago. This report may have served as the model for the ATF test as the
Bureau of Mines has this journal translated on a regular bases, although the
three articles on fireworks that have been published do not appear in the
translated edition. Apparently the Bureau of Mines feels that information on
blowing up fish is more important then preventing accidents in the fireworks
industry!

The following is from the English summery:

Fireworks compositions "were piled on the ground or on a concrete-floor in 5kg,
30kg, 50kg or 100kg and they were ignited with two squibs combined with
powder pasted paper, Yakushi, or for some samples with two detonators. From
37 tests the reaction modes were classified into three: combustion, deflagration
and detonation. Most gerbs showed combustion or deflagration except when a
composition contained fine aluminium, the particle size of which was less then
300 mesh. The reaction of the composition with fine aluminium was promoted
to detonation. [Emphasis added. WiZ] The star grains of 1ookg shifted to
detonation from several ten millisecond combustion and in other cases they
showed combustion or deflagration. The star composition powders showed
combustion even with a quantity of 100kg."

The above information was taken from those parts of the paper that were in
English, i.e. the tables. Just what "star grains" are, is not reported in English.

Measurement of Pressure and Related Energy Output from Thermally Ignited
Pyrotechnic Compositions Burning in a Partally Vented Vessel P.L. Farnell. 1981.
NTIS ADA-100728.

"The results of the tests described in the report indicate that pyrotechnic
compositions are indeed hazardous and that new criteria are required to judge
their hazardous nature, rather then attempting to apply nonapplicable ones used
for explosives. For example, explosives reach a high pressure very quickly
resulting in a large blast wave, but the extremely short duration yields a
relatively small impulse imparted to contingent walls of a room. The blast wave
also tends to be more directional. This is more likely to punch a hole in a wall or
break it into small pieces, as form a hammer blow. In addition, a large pressure
from the blast wave is relayed outside the room, if one wall is left open.
Pyrotechnics, on the other hand, produce lower pressure but last longer, giving a
large impulse to the whole wall which can push the wall down. Little pressure is
relayed outside since the buildup is slow and there is little or no blast wave.
Thus; adjacent buildings would be less endangered from the blast wave, at a
closer distance, then from an explosive. However the extreme heat developed by
some burning pyrotechnics can be of greater danger than the pressure; ** With
proper venting, pressure from the combustion of pyrotechnics could be held to
small values; but the heat and flame generated could harm people in the area,
could set fires, or could even ignite other compositions located nearby.

Finally, it is possible, with sufficient confinement producing a large pressure
buildup, to cause the burning of some of the pyrotechnics to become a low
velocity detonation at which point explosives criteria would apply. One should
bear in mind, however extremely hazardous nature of pyrotechnics
deflagrations, and the need to develop appropriate criteria for describing their
outputs."

Deficiencies in the Testing and Classification of Dangerous Materials. J.E. Settles.
1968. Annals New York Academy of Sciences, Volume 152, Art.1. Pages 199-205.

"A total of 103 persons suffered injuries in the 81 accidents. Seventy-eight
fatalities resulted from these 81 accidents. "Of the 81 accidents included in this
analysis, it was concluded that 23 of them involved only fire, and the principal
hazard was radiant heat. It was further concluded that 44 of the accidents
involved both fire and explosion. From information available, it seemed justified
to assume that no more then 14 of the accidents were characterized by
supersonic shock waves that would fall within the accepted definition of
"detonating" reactions.

"The 14 accidents in which detonating forces were present resulted in injuries
to 35 persons and 34 fatalities. It appears from the information available that
only one of these 34 deaths resulted from the blast overpressures that are
associated with a detonating reaction. However, this one fatality was not the
result of blast damage to human tissue. Rather, the blast pressure caused this
individual to be propelled as a projectile. The other 33 persons who died in these
14 accidents were located at points where the density of flying fragments, and in
some cases, the lethal searing of radiant heat were so great that their deaths
were certain, even though there had been no blast effects.

"A SERIOUS AND DISTURBING INCONSISTENCY IS RELATED TO THE PRACTICE
OF ACCEPTING A "FIRE HAZARD ONLY" LABEL ON REACTIONS OF SUCH
VIOLENCE AND DESTRUCTIVE ENERGY AS MEDIUM-VELOCITY DETONATION,
LOW-VELOCITY DETONATIONS, HIGH-RATE EXPLOSIONS, MEDIUM-RATE
EXPLOSIONS, LOW-RATE EXPLOSIONS, AND EVEN REACTIONS THAT DON'T
EXPLODE AT ALL BUT KILL PEOPLE BY BURNING THEM TO DEATH."



prometheus1970 - 16-10-2010 at 17:56

Thanks, that helps...

nitro-genes - 19-10-2010 at 14:35

The speed by which flashpowder can "burn" also greatly depends on quantity, confinement and/or how it was initiated. In a small papertube and fuse initiated it will not reach more than maybe 500-1000 m/s. IIRC, well prepared chlorate/DG aluminium flash can reach 2500 m/s when initiated by a detonator. But peakpressures don't come close to that of even ANFO.
We are talking maybe 2 kilobar for flash, while even ANFO can reach peak pressures up to 40 kilobar! Too put things more in perspective, RDX or PETN produce a whopping 340 kilobar, thats 100 times as brisant as flash! Confined in a strong metal pipe, flash or blackpowder will only rupture it, or split it in two, with ANFO you get hundreds of fragments, while really brisant explosives will produce thousands of tiny fragments. The problem is that there is hardly any gas formation, the formed KCl stays in gas form for some time, adding to the blast the blast effect, but the aluminium oxide is just "dead weight". The amount of inert mass makes that the shockwave is not able to accelerate as fast as in explosives that have both the oxygen and fuel within the same molecule like most HE's.

Hardly anything in nature however fits in well defined categories, same goes for detonation or deflageration. You could for example steadily add more TNT to your chlorate, thereby increasing VoD and peakpressures, but from which point would you consider it to be detonation instead of deflageration? :)

[Edited on 19-10-2010 by nitro-genes]

gregxy - 19-10-2010 at 15:09

One way to tell the difference between burning and detonation would be how the sample responds to pressing.

Burning propagates by the flow of hot gasses through the sample, while denonation propatates by a mechanical shock wave. When solidly pressed, burning slows down since it becomes more difficult for the hot gasses to pass through the
sample. A shock wave on the other hand would speed up
due to the greater density.

If flash powder stops "exploding" when solidly pressed it is burning rather than detonating.

Flash powder is quite sensitive to impact, and is most likely
capable of being detonated, but when placed loosely in an
"M80" it is just burning quickly.


Mr. Wizard - 19-10-2010 at 19:11

When you can put two grams of 'flash powder' next to a heavy framing nail, and after it goes 'BANG', it has put a >45 degree angle in the nail, I'll consider it may have detonated instead of burned. Mercuric Fulminate / KClO3; 80/20 will do this with no confinement. The dead press argument may not hold true with some explosives that require air bubbles or spaces in their mixture to propagate the shock wave. I understand the argument about the hot gas getting around the grains, but it always isn't that simple. Increasing density of some explosives doesn't make them work better.

Microtek - 21-10-2010 at 11:39

There is pressing and there is deadpressing. I don't think gregxy meant applying enormous amounts of pressure to the sample, but rather just a moderate amount, say a few hundred psi. This will compact the loose powder into a pellet, and if this pellet is then initiated with a detonator the response will tell you if there was a propagated detonation or not.
Obviously, depending on your available hardware, you may have to make a quite long charge to be able to definitively distinguish between true propagation of detonation and simple shock induced decomposition that isn't able to self-propagate.

KNO3me - 24-10-2010 at 00:34

Quote: Originally posted by gregxy  
One way to tell the difference between burning and detonation would be how the sample responds to pressing.

Burning propagates by the flow of hot gasses through the sample, while denonation propatates by a mechanical shock wave. When solidly pressed, burning slows down since it becomes more difficult for the hot gasses to pass through the
sample. A shock wave on the other hand would speed up
due to the greater density.

If flash powder stops "exploding" when solidly pressed it is burning rather than detonating.

Flash powder is quite sensitive to impact, and is most likely
capable of being detonated, but when placed loosely in an
"M80" it is just burning quickly.





This is quite true. I remember when I tightly pressed 50/50 KClO3/Mg flash powder into a little cardboard tube with end plugs glued on with a hot glue gun. When I tested the salute, it failed. Well, it wasn’t a complete failure it did shoot beautiful white sparks from its side.
http://www.youtube.com/watch?v=WjJid8WOW9o
I was surprised and baffled to see my cracker shower like a fountain. I thought solidifying LE’s would produce a faster reaction thus making a louder report but apparently not. Through that experience I’ve grown a little more in knowledge.
Not all flash powders are sensitive to impact. Sensitivity varies on the flash composition.
50/50 KClO3/Mg is pretty sensitive. http://www.youtube.com/watch?v=GAsqsDL-Gxk
50/40/10 KNO3/Mg/S is pretty stable. http://www.youtube.com/watch?v=DcxkEwdghZg
The famous 70/30 KClO4/Al is very stable but can explode under the right amount of impact. Sorry that I don’t have video evidence of it but I’m working on it. The flash powder is really hard to set off with a mini sledge hammer.
Since we’re talking about flash powders and detonation I would like to share this with you guys.
http://www.youtube.com/watch?v=nJGHdEVcm4k

Blasty - 25-10-2010 at 21:59

Quote: Originally posted by KNO3me  
Quote: Originally posted by gregxy  
One way to tell the difference between burning and detonation would be how the sample responds to pressing.

Burning propagates by the flow of hot gasses through the sample, while denonation propatates by a mechanical shock wave. When solidly pressed, burning slows down since it becomes more difficult for the hot gasses to pass through the
sample. A shock wave on the other hand would speed up
due to the greater density.

If flash powder stops "exploding" when solidly pressed it is burning rather than detonating.

Flash powder is quite sensitive to impact, and is most likely
capable of being detonated, but when placed loosely in an
"M80" it is just burning quickly.





This is quite true. I remember when I tightly pressed 50/50 KClO3/Mg flash powder into a little cardboard tube with end plugs glued on with a hot glue gun. When I tested the salute, it failed. Well, it wasn’t a complete failure it did shoot beautiful white sparks from its side.
http://www.youtube.com/watch?v=WjJid8WOW9o
I was surprised and baffled to see my cracker shower like a fountain. I thought solidifying LE’s would produce a faster reaction thus making a louder report but apparently not. Through that experience I’ve grown a little more in knowledge.
Not all flash powders are sensitive to impact. Sensitivity varies on the flash composition.
50/50 KClO3/Mg is pretty sensitive. http://www.youtube.com/watch?v=GAsqsDL-Gxk
50/40/10 KNO3/Mg/S is pretty stable. http://www.youtube.com/watch?v=DcxkEwdghZg
The famous 70/30 KClO4/Al is very stable but can explode under the right amount of impact. Sorry that I don’t have video evidence of it but I’m working on it. The flash powder is really hard to set off with a mini sledge hammer.
Since we’re talking about flash powders and detonation I would like to share this with you guys.
http://www.youtube.com/watch?v=nJGHdEVcm4k


Nice videos. Have you tested how stable are the flash powders using sulfates, like barium sulfate? They are said to be very stable:

http://www.pyrosociety.org.uk/forum/topic/3651-safest-flash-...

"If you want a super safe flash composition you could try one based on barium sulfate and dark pyro. Supposedly (although it's recreational pyrotechnics so take it with a grain of sodium chlorate) this stuff even makes a nice noise in open tubes.

The ratios are Barium Sulfate 6, Aluminum (Dark Pyro) 3, Sulfur 1.

It's a cheap flash powder too since barium sulfate is easy to come by."

[Edited on 26-10-2010 by Blasty]

nitro-genes - 25-10-2010 at 22:44

Behaviour to pressing I think is a very good point. There is however also a certain minimum quantity, (call it critical diameter) involved. IIRC, in huge amounts even blackpowder can detonate, TNO tested some fireworks in large containers, one of which were rocketmotors wich consist of well pressed BP, and sparkler fountains. Both were able to go high order when lid in 5000 kg+ quantities with confinement. This was after the explosion of a fireworks factory in the netherlands, of which the explosion had such force, people were certain some HE was involved...

http://www.youtube.com/watch?v=B00E3ugt3bI

[Edited on 26-10-2010 by nitro-genes]

gregxy - 26-10-2010 at 13:17

I think that the main point is that pressing (or increasing the density) should improve the performance of almost any explosive when it is initiated by a primary.

However pressing seems to have the opposite effect on the DDT,
i.e. many primaries can be "dead pressed". The most likely reason for this is at some point hot gasses connot move in between the grains so burning can only progress by heat
condution which is very slow. Thus there is an optimal
density the both allows the detonation wave to move
rapidly yet still allows rapid burning.

Going back to flash power, if packed and initiated by a blasting
cap it most likely will detonate, (depending on the diameter
density etc). However in an firecracker, conditions don't
seem very good for the DDT process. And most of the
firecrackers I have seen left large paper fragments and
were incapable of doing much damaged when placed on
a flat piece of wood.

Blasty - 3-12-2010 at 10:49

Quote:
The ratios are Barium Sulfate 6, Aluminum (Dark Pyro) 3, Sulfur 1.


I recently tested this mix to see how it burned. Instead of using dark pyro aluminum, though, I used atomized (spherical) aluminum but in very fine powder (3000 mesh.) The thing is quite difficult to ignite, but once it does it flashes nicely. Sometimes the regular visco fuse I use just runs right through a small pile of the powder without igniting it (the ejecting gases from the fuse tend to scatter the flash powder and do not give it enough time to get hot enough for it to ignite.) A slower burning fuse helps avoid this from happening. Putting a little bit of granulated black powder on this mix it ignites readily even with the faster fuse.

I also tried an old firecracker mix (equal parts sulfur, potassium perchlorate, aluminum and barium nitrate) with this fine atomized aluminum powder and even that more sensitive mix was pretty difficult to ignite! Once it does, though, gives a nice flash.


[Edited on 3-12-2010 by Blasty]

The WiZard is In - 3-12-2010 at 13:20

Quote: Originally posted by Blasty  

I recently tested this mix to see how it burned. Instead of using dark pyro aluminum, though, I used atomized (spherical) aluminum but in very fine powder (3000 mesh.) The thing is quite difficult to ignite, but once it does it flashes nicely. Sometimes the regular visco fuse I use just runs right through a small pile of the powder without igniting it (the ejecting gases from the fuse tend to scatter the flash powder and do not give it enough time to get hot enough for it to ignite.) A slower burning fuse helps avoid this from happening. Putting a little bit of granulated black powder on this mix it ignites readily even with the faster fuse.

I also tried an old firecracker mix (equal parts sulfur, potassium perchlorate, aluminum and barium nitrate) with this fine atomized aluminum powder and even that more sensitive mix was pretty difficult to ignite! Once it does, though, gives a nice flash.



Before I once again post a note on terminology —

Flash refers to flash powders - think photoflash and Special F/X flash pots. (Usually Mg and SrNO3).

The comp in firecrackers/M80's &c. is Flash and report.


Plaster of Paris Flash-Powders
BY RICHARD J. SANFORD
American Pyrotechnist Fireworks News
Volume 7, Number 6 June, 1974 Issue Number 78

In the April issue (page 506) two star compositions are described
which combine Plaster of Paris with other oxidizers to produce
unusual effects. I'm glad that you have stirred up interest in
unconventional oxidizers; the present article is my own contribution to the subject.

Ellern has reported the use of Plaster of Paris (calcium sulfate,
CaS04 * 1/2(H20)) and other sulfates as substitutes for part of the
nitrate in World War II flare compositions.* The following article
describes two flash compositions which use Plaster of Paris as the
only oxidizer. Such formulations are most easily illustrated by the
composition:

Plaster of Paris - 1.3 / magnesium powder - 1.0

Estimating the heat of formation of calcium sulfate as 372
kilocalories/mole, the reaction:

2(CaSO4 - 1/2(H20)) + 9 Mg ? 2(CaS) + 9(MgO) + H2

gives a theoretical yield of 33 kcal/gram. The hydrogen should also
burn when it reaches the air, adding to the energy yield. If made
with good quality magnesium powder, this mixture can be ignited
by ordinary pyrotechnic safety-fuse. If not, it can usually be ignited
for demonstration purposes by placing one end of a book of
matches in the composition and lighting the other end of the train of
match heads. The mixture burns quickly.

Aluminum dust can also be burned with Plaster of Paris'. The
reaction:

2(CaSO4 - 1/2(H20)) + 6 Al ? 2(CaS) + 3(AI203) + H2

yields 32.4 kcal/gram-atom or 1.5 kcal/gram. The corresponding
composition is:

Plaster of Paris - 1.8 / aluminum dust - 1.0

This mixture is very hard to light. The matchbook trick will not do it,
but it can be ignited by a small quantity of the Plaster of
Paris/magnesium mix or by a conventional flash powder such as:

potassium nitrate - 5 / sulfur - 3 / aluminum – 2
The Plaster of Paris/aluminum powder burns quickly if made with
pyro aluminum, more slowly if aluminum paint pigment is used.

The triangle cracker described on page 375 of the May 1973
APFN provides sufficient confinement for this mixture to be used in
firecrackers. First, the fuse is inserted into the powder-pocket, and
a small amount of first-fire igniter is added. This can be a
conventional flash powder, black powder, or even the heads torn
off 10 book-matches. Then the Plaster of Paris/aluminum mixture is
poured on top of the first-fire and the rest of the cracker is folded
and sealed into the equilateral triangle shape. When the flame is
confined inside the cracker, it becomes much more effective in
lighting the hard-to-ignite powder than when in the open.

In use, the fuse burns down through the main charge and into
the first fire before the cracker explodes. This minimizes the danger
of throwing a piece of still burning fuse when the cracker bursts, but
the added delay may cause an uninitiated observer to jump to the
conclusion that the device is a dud. The method of loading the
cracker is shown at the right.

Plaster of Paris is available in most hardware stores. Aluminum
dust used to be available in most paint stores, but now most people
seem to want their aluminum paint pre-mixed. The dry powder can,
however, be obtained from the manufacturer. I recently got a pound
of "Chemically Pure Aluminum Bronze Powder" from the Sheffield
Bronze Paint Corporation, 17814 Waterloo Road, Cleveland, Ohio
44119. It cost $3.69 plus 64 cents shipping charges, and it smells
oily, but this paint pigment may be the best metal fuel available if
the Consumer Product Safety Commission bans the sale of
pyrotechnic chemicals.

Editor's note: like the compositions described in the article referred
to by Mr. Sanford, the present two can be termed "home-tested"
and quite effective! A triangle cracker charged with about a
half-gram of the magnesium / Plaster of Paris composition was
easily ignited by 3/32" safety-fuse, with no first-fire mixture needed,
and exploded with a surprisingly loud bang. We used 100-mesh
magnesium powder and Rexall casting plaster from a jar that has
stood in the shed for years, 1.3 grams of plaster to 1.0 gram of
magnesium. Following recommended safety practice for any flash
composition, these were merely mixed by turning together in a
plastic container for Kodak 35mm film cartridges) until the mix
showed a uniform grey color, about 2 minutes, with no attempt at
further pulverization or incorporation. This was loaded in a triangle
cracker 1.5" on each side, with only the final fold secured by
cellophane tape. The report easily exceeded that of a Class C
flashcracker and had all the dogs within several blocks barking!

For comparison, we loaded a similar cracker with only
magnesium powder, which was also easily ignited by the safety
fuse, making a bright flash and a pretty good "pop", but nothing to
compare with the metal/oxidizer mix. Ignition of the magnesium
alone would, of course, depend on the entrained air in the cracker,
but we mention this experiment to point up how flammable and un-
predictable all finely-divided metals can be, even with no oxidizer
added. A recent news story told of severe injuries suffered by a
youth experimenting with "incendiary metals," and magnesium is
one of the most incendiary, so USE EXTREME CAUTION! It is
probably unnecessary to mention that one should never try to put
out a magnesium fire with water, which merely scatters and in-
tensifies the flame.

As a final backup to Mr. Sanford's article, we made a triangle
cracker with a mixture of 1 gram of Cres-Lite aluminum bronze
powder and 1.5 grams Plaster of Paris. This was also easily ignited
by the fuse, with no first fire needed, and burned with a "whoosh"
ending in a violent "pop". Unfortunately, the device demonstrated
more characteristics of a rocket than a cracker during the "whoosh"
part, with a jet of flame from the fuse orifice propelling it several
yards into some adjacent tinder dry grass, setting it afire! Thus, by
mandate of the wife, our experiments were abruptly terminated.]

---------
The tri-angle crackers mentioned in this article APFN pg. 527
June. 1974 By Phil Vander Horck, were originally described by
Mike Gage writing from Ceylon. American Pyrotechnist Volume 1
August, 1968 Number 8. However, they have an earlier history.
They were patented by; SS Yenovkain. US Patent 600 190
8 March 1898! [djh]

Do be finding attached my PGII article 'bout sulphates as oxidizers.

Attachment: Fireworks Sulphate.pdf (46kB)
This file has been downloaded 1819 times

quicksilver - 3-12-2010 at 15:14

I really wish all the material back from UseNet (news groups) were more easily available today.......all of this had be pretty well hashed over with some damn good articles. Now the News-Groups are a "special order" issue with internet.

The WiZard is In - 3-12-2010 at 16:55

Quote: Originally posted by quicksilver  
I really wish all the material back from UseNet (news groups) were more easily available today.......all of this had be pretty well hashed over with some damn good articles. Now the News-Groups are a "special order" issue with internet.


Most of the news group text (All graphic content not archived and
if its not posted as a straight text file it also was not saved)
can be found using www.deja.com. Deja.com was bought
out by Google some years ago and can also be accessed as
www.google.com — got to More and click on groups.

My slow - unreliable ISP (Hughes Net) doesn't not support newsgroups at all so I have to use Google.

There are commercial ($) sites that provide access/archive
to binary newsgroups.

quicksilver - 4-12-2010 at 06:21

Thanks!
My ISP does not offer it either and I miss it.
I have the same deal: to pay extra - for what???? Those were the original discussion groups. The lame porn and crap was put up on a sectional basis. I didn't even know anyone that desperate to join 5 sections of whatever to get a picture or binary.

I had dial-up of course and would constantly strive to get the most out of my modem. Indeed; I remember.....

[Edited on 4-12-2010 by quicksilver]

The WiZard is In - 4-12-2010 at 07:49

Quote: Originally posted by quicksilver  
Thanks!
My ISP does not offer it either and I miss it.

I have the same deal: to pay extra - for what???? Those were the
original discussion groups. The lame porn and crap was put up on a
sectional basis. I didn't even know anyone that desperate to join 5
sections of whatever to get a picture or binary.

I had dial-up of course and would constantly strive to get the most
out of my modem. Indeed; I remember.....



Before there was the internet as we now know it there were
RBBS - Remote Bulletin Board System(s) they were usually
a lone PC siting in someones bedroom with a 300/1200 dial up
modem. Access could be a pain and expensive this being
when LD phone calls were expensive and as they usually had
a single number getting in could take a zillion redials. At
300/1200 binaries were not doable ACII art was as close
to binary as the tech allowed. When 2400 modem became
affordable binaries became popular. For the gynecology through
the picture study method
Rusty and Eddies was one of
the more popular ones .

http://en.wikipedia.org/wiki/Rusty_n_Edie%27s_BBS

A particular problem with the early ones was if the last called
failed to log-off and simply hung up or was disconnected it
locked up the PC until the SYSOP reset it.

For the tech/software minded there was the Invention Factory located
in lower Manhattan. It was pay to play, however, as it was
a local call it prevented my phone bill from looking like the
national debt! And it had a number of access lines.

Then there was the — WCPB - West Coast Pyro Board.

The earliest post found in my files is message # 18, from founder
Daniel G Hyman to Bonnie Kosanke, 24 November 1987.

The board was run on a dual floppy IBM-PC located at Primo Fireworks
with a 300-1200 baud modem! Thanks to a contribution from Id a 2400
baud modem was had. In la files there is a post noting that a 20 Meg HD
was purchased. [The first HD I bought was 10 Meg, they made 5's.]

I don't know when the fuze went out at the WCPB. The last posts I have
are from 1990. I also have copies of the Print Edition of the WCPB,
September - October - November 1990.

Anyone remember .ARC files?
http://en.wikipedia.org/wiki/ARC_%28file_format%29

X, Y, and Z Modem?
http://en.wikipedia.org/wiki/XMODEM

Fido Net?
http://en.wikipedia.org/wiki/FidoNet



quicksilver - 6-12-2010 at 07:19

YES!
My first machine was an Eagle business machine ('79) that ran off of a floppy (5.25) that used CPM (I sold them and repaired them: '86). But my first communications computer was an XT that was almost useless but it DID have an internal MFM drive (& a 1200) that was 20Mb! Then I got an AT (a 286) that had a 2400. but there wasn't even a continuous line to the university.
Not only do I remember ARC files I remember all the switches for PKZIP when it came out. I remember the various Z modem switches and I still have have out-board US Robotics Courier modem! I have one of the last ones: the ones that promised 54 KBd but never delivered. All the monitors were Amber or green until they started selling "VGA" and the Hercules graphics cards fell into disuse.

You're going back in time.
I HAD a little BBS back then. A collection of us worked in a software store and I worked in a repair place. It was my little Compaq 386 that was the first one or the BBS - then I got a 486 DeskPro (that had an internal: 2400) that was running the BBS for about 2 yrs (until I got an external that was a 14.4 Intel). I went through some others & eventually I made the move to a USR 56. I shut the BBS down when I moved.

I still have my "best modem" that was an external USR 56K & that modem was the top of the line, principally because it cost so damn much back then and still gets one of the fastest FAX responses I've seen. That's when all of USR was built in Canada.
I always had USR firmware updates: I remember that everyone had to get the same firmware updates to get the "blinding speed" promised.
Remember TelNet? That was the 1st "chat".

The pyro files were in a section of text files (on my BBS) and there was a UUN-Code or something of sending graphics around; but I don't remember. I had a 40Mb drive. I had to dial up the university to get on to a network to access the different libraries of the universities on that system. And they would work one day and be down the next. That;'s where a lot of pyro material came from that was not real hobbyist stuff.
I really DO remember!

In XT and AT days 640K was a LOT of RAM: one megabyte was impossible to utilize unless you had DOS 3.31 which had "SMARTDRV.EXE", "HIMEM.SYS" in your autoexec.bat and your drivers in proper order in your config.sys file. Folks wrote their little office materials in "QuickBasic" & loved their DOSKEY commands for any continued work.....
I remember very well.....

[Edited on 6-12-2010 by quicksilver]

Mumbles - 7-12-2010 at 22:34

Quote: Originally posted by nitro-genes  
Behaviour to pressing I think is a very good point. There is however also a certain minimum quantity, (call it critical diameter) involved. IIRC, in huge amounts even blackpowder can detonate, TNO tested some fireworks in large containers, one of which were rocketmotors wich consist of well pressed BP, and sparkler fountains. Both were able to go high order when lid in 5000 kg+ quantities with confinement. This was after the explosion of a fireworks factory in the netherlands, of which the explosion had such force, people were certain some HE was involved...

http://www.youtube.com/watch?v=B00E3ugt3bI

[Edited on 26-10-2010 by nitro-genes]



I've been looking for the source for the last 20 minutes, but I can't seem to find it. I could have sworn that I read somewhere they had to, or at least did, significantly reinforce the shipping containers used by NTO to get them to blow up like that and use unnatural shipping conditions. Welded doors, reinforced walls and ceiling, no shipping boxes, product loaded loose packed to the gills, etc.

I am of the opinion that most traditional (KNO3 or KClO4) flash powders cannot detonate under normal circumstances. When you get into things like Ammonium perchlorate flash, or chlorate flash things may start to go high order if the conditions are right. I do not consider blasting caps being placed into the salutes to be "normal circumstances". I've witnessed salutes as large as 50lbs in heavily reinforced containers, and they seemed no different than a "normal" salute except for percieved volume and kick in the chest.

It's fairly commonly known that the more flash you can pack into a container, the stronger and louder the resulting salute. I don't know if this is just because of extra material, or some sort of DDT. You can certainly press it to the point that the flame cannot propagate freely. If you took a longer cardboard tube, say 1" ID x 10" long and loosely fill, it will explode. If you took the same tube, and settled and tamped the powder down, it will still explode, probably louder. If you took the same tube and powder, and pressed it into a solid grain like a rocket, it would likely burn only on the surface and probably look like a fountain. I know of one gentleman who did the last experiment, and even put a core into it. It resulted in a hellacious flight, but no explosion.

[Edited on 12-8-2010 by Mumbles]

Blasty - 14-12-2010 at 19:53

I just finished testing this 3000 mesh atomized aluminum with barium perchlorate and sulfur, in the following proportions:

0.3 grams barium perchlorate

0.2 grams aluminum

0.1 gram sulfur

Since barium perchlorate is somewhat hygroscopic it was heated so that no moisture remained in it, then ground in the same porcelain dish where it was being heated, leaving a fine dry powder of the salt. It was then "diapered" with the other two chemicals while still warm. I was expecting that this mixture would give a deeper green flash than similar mixtures using barium nitrate, or barium nitrate + potassium perchlorate, but it was hardly an improvement, only a slightly more greenish-tinged flash seems to have resulted.

Only 0.6 grams of the unconfined flash give a loud "THUMP!" This mixture in confinement will very likely give quite a loud report. Despite the fact that it seems stable during mixing, I would not recommend mixing more than about a gram or so at a time. It might have a low "critical mass" and be capable of exploding unconfined in somewhat larger quantities.

The apparently common belief that atomized/spherical aluminum is rather worthless for flash powders seems to only be true of the "regular" mesh sizes. When you get to such a small particle size as 3000 mesh, this type of aluminum seems to work quite well, giving quick bright flashes and loud "thumps!" with a variety of oxidizers.

quicksilver - 15-12-2010 at 07:42

The Eckart company is a pigments firms and Eckart 5413 is what is known as an "ink grade" silver pigment. There was a time when this was especially fine and pure being kept at 2um. That material was never sold in bulk 30 lbs plastic pails but was manufactured specifically for a silver ink. The material today is Ekart's "5413-style" aluminum which despite some notions to the contrary was atomized and could indeed be of a "micro granular" configuration. A flake so small that it starts to have side equal to it's length. It's not truly round in the strictest sense but it's not really a flake either.
Alfa Asar once sold a single micron aluminum that may have been the Ekart product prior to any handling. It was 2 microns; never more or less. The amount of grading needed for this to be achieved is pretty fantastic. It was enormously expensive (as are all their element samples) and sold in 5-50 grams lots. it would not be available in pyrotechnic weights & would never really practical to be sold as such. The "5413-style" Al is a collection of that companies first standard prior to it's being "ink graded".

ALCOA Aluminum has made some material for the military in both the USA and certain NATO countries. THEY have made ton lots of micron fine Al in what was known as "blast-grade" aluminum. Much of that had eventually found it's way to the surplus market & eventually to "pyro dealers". Large containers of 600 mesh eventually, because of movement & grinding-action have some of the smallest isolated Al powder obtainable. At the "bottom of the barrel" is often large collections of Al almost unobtainable in a directly manufactured manner. I have seen some of that as well as copper powder that has been shaved and ground from large lots being transported that was MUCH finer than commonly measured sizes ( two microns, etc).



edit;

Note that this is the stuff that is truly dangerous both to heath and as a horrifying flash as it can easily imitate "air float charcoal". I once saw some one demo a VERY small amount of Al (not more than a gram) in a concrete walled furnace area and it flash burned a pile of cotton clothing nearly a meter away.

[Edited on 15-12-2010 by quicksilver]

The WiZard is In - 15-12-2010 at 08:02

Quote: Originally posted by Blasty  
I just finished testing this 3000 mesh atomized aluminum with barium perchlorate and sulfur, in the following proportions:

0.3 grams barium perchlorate

0.2 grams aluminum

0.1 gram sulfur


Try barium nitrate w/o da sulphur.

The WiZard is In - 15-12-2010 at 08:06

Quote: Originally posted by quicksilver  

[snip]

edit;

Note that this is the stuff that is truly dangerous both to heath and as a horrifying flash as it can easily imitate "air float charcoal". I once saw some one demo a VERY small amount of Al (not more than a gram) in a concrete walled furnace area and it flash burned a pile of cotton clothing nearly a meter away.


Extracted from:

Journal of Hazardous Materials, 5 (1982) 359-371 Elsevier Scientific
Publishing Company, Amsterdam - Printed in The Netherlands


REMOTE HANDLING - BLENDING OF ENERGETIC MATERIALS
R. L. PARKS
Monsanto Research Corporation, Mound Facility,* Miamisburg, Ohio

In 1974 to meet a need for a less sensitive, but still energetic,
explosives initiator other than the commonly used primary explosives,
such as lead azide, Monsanto Research Corporation started the develop-
ment and production of a series of high energy pyrotechnics. It soon
became apparent that these high energy pyrotechnics were not simple
mixtures, easily handled, or subject to deflagration only. There was more
to it. The safety literature and technical data on pyrotechnics did not deal
fully with the materials under study. In-house work on small quantities,
less than a gram, indicated that these metal/oxidizer blends were truly
high energy mixtures.

Important production safety questions quickly surfaced. How large a
batch could be blended safely? Was there a "critical mass” for detonation?
How important was container shape and size? If these pyrotechnics
detonated, what would be their TNT equivalency On deflagration, what
would be the size of the “fireball”?

[0.5 kg (1.1) lb 10 feet] 260 ms duration.]

The objective of the test series was to determine the output energy of
the titanium powder and potassium perchlorate mixture in a mechanical
blender configuration representative of that used at Mound Facility. This
was accomplished by measuring: (1) the free field air blast output
equivalency as compared to an equal weight of TNT at the same scaled
distances;,(2) fireball diameter and duration; and (3) static pressure in a
closed chamber.

The composition tested consisted of one-third by weight of 2-micron
particle size dry titanium powder and two-thirds by weight laboratory
grade KCl04. The number of tests and the quantities of ingredients for
each test conducted are tabulated in Table 1. Five of the nine tests were
conducted in a simulated blender configuration to determine free air
equivalency, and the remaining four tests were conducted in closed
chambers to measure static pressure.


The Ti/KCl04 mixture exhibited characteristics of a detonation when
thermally ignited in a light, metal container. For the 500-g (1.10 lb) charge,
the TNT equivalent value was 53% at a scaled distance of 1.07 m/kg sup
1/3 (2.22 ft/lb sup 1/3) and approximately 75% equivalency at a scaled
distance of 3.24 m/kg sup 1/3 (8.16 ft/lb sup 1/3). Equivalent values for
the 250-g (0.55-1b) charge weight were 68% equivalency at the 1.07-m/kg
sup 1/3 . Because of the limited number of tests, it cannot be determined
whether the apparent difference at the smaller distance is significant. The
125-g (0.28-1b) quantity failed to detonate. This was probably due in part
to the volume of the container and the resultant depth of material.

A fragment analysis was made on the assumption that a detonation of the
pyrotechnic would occur in the hopper of the aluminum aliquot vessel. It
was also assumed that the detonation would equal 1 lb. of TNT, and that
all available material would detonate, the worst case. THE 0.5-in. THICK
STEEL WALLS WILL NOT STOP A PRIMARY FRAGMENT, 1/8 x 1 x 1
in. ALUMINUM, STRIKING IT AT RIGHT ANGLES.
[emphasis added]


[How thick is your skin?!?!]

Blasty - 15-12-2010 at 12:06

Quote: Originally posted by The WiZard is In  

Try barium nitrate w/o da sulphur.


I tried barium nitrate + potassiun perchlorate + this very fine atomized aluminum powder

It gave a quick bright flash (though not very green, as I was expecting it would) and a nice "thump!". It was a bit difficult to ignite, though.

quicksilver - 15-12-2010 at 13:14

I may have the same text (or gotten an excerpt from you) as I remember the "TNT equivalent value was 53%" .
At one time Monsanto was a very progressive, aggressive research outfit. Their contributions to science on various levels, in a variety of areas has been quite impressive. Just a passing of the patents w/ their name is staggering.

When the debate was in full gear (flash: detonate; bla, bla) I believed what I read that it was a question of the method of initiation. If flame, spark = no and if some "molecule breaking force" (a primary explos. or plasma energy or even high current / voltage discharge) yes. But quality science such as Monsanto's was simply not taken into account. Neither was the unique formats of the composition elements and methods of mfg.

Entirely opinion but once particulate reaches a certain size (smaller than blood cells) I think perhaps the opportunities for a true detonation change. I also remember Konski's "Swedish Perchlorate" & one feature was it's particulate size as apparently it was milled to a remarkably small size. I still have some and some time back examined it to see if there was a large (proportionately) level of Cab-O-Sil. I could not find what I considered a significant amount (>1%) using oil/lens magnification.
So intimate a mixture can be achieved with really single or sub-micron size particulate; that I believe that is where a significant issues exists. Yet that is one area where a great deal of examination is absent; the condition of the oxidizer.



Edit:

If you want color - you generally need some chlorine. On occasion some of a lightest amount of parlon will yield some of the most brilliant coloration.
However the peroxides (as used in tracer composition) will get some fantastic color.

[Edited on 15-12-2010 by quicksilver]

crazedguy - 15-12-2010 at 16:55

Quote: Originally posted by quicksilver  


Edit:

If you want color - you generally need some chlorine. On occasion some of a lightest amount of parlon will yield some of the most brilliant coloration.
However the peroxides (as used in tracer composition) will get some fantastic color.

[Edited on 15-12-2010 by quicksilver]

Could you give more info on this or a source? For a while now I have been looking for a way to color my flash compositions, but as color I don't mean the burning I mean like the color of an M80 going off. Just haven't been able to find something that actually worked for that.

Blasty - 15-12-2010 at 17:24

Quote: Originally posted by quicksilver  
Edit:

If you want color - you generally need some chlorine. On occasion some of a lightest amount of parlon will yield some of the most brilliant coloration.
However the peroxides (as used in tracer composition) will get some fantastic color.


Perchlorates and chlorates already have chlorine. If you mix the barium and strontium ones with some organic chemicals (hexamine-sugar-chromate mixtures or nitrated cellulose powder, for example) instead of metals, you get rich colors, but the burning rate is slower than flash powders (except in the case of guncotton soaked in solutions of these salts and then carefully dried; that gives a fast colored flash.)

Mumbles - 15-12-2010 at 23:13

If you're trying to make colors, why use aluminum? The purest colored flash powders are all made with magnesium for a reason. The aluminum oxide formed is a fairly decent white light emitter, which will wash out or over power any colorant that may be formed. You can get around this by a relative excess of chlorine to form aluminum chlorides, which are far more flame transparent. Magnesium oxide doesn't obscure visible colors nearly as much. I'm told it emits more in the UV, but I haven't looked at a spectra recently to check that out.

Some extra chlorine in the flame will ensure a greater concentration of the BaCl emitting species, which is the one you want. Otherwise you get some BaOH, amongst other things, which is more of a yellow-green to lime green color. Sulfur can help to generate free chlorine in a flame, but the chlorine is already where you want it when starting with barium perchlorate. If it behaves anything like barium chlorate, I'm not surprised it's underwhelming. For having the reputation of instability, it can be a somewhat sluggish oxidizer.

quicksilver - 16-12-2010 at 07:16

Quote: Originally posted by Mumbles  

Some extra chlorine in the flame will ensure a greater concentration of the BaCl emitting species, which is the one you want. Otherwise you get some BaOH, amongst other things, which is more of a yellow-green to lime green color. Sulfur can help to generate free chlorine in a flame, but the chlorine is already where you want it when starting with barium perchlorate. If it behaves anything like barium chlorate, I'm not surprised it's underwhelming. For having the reputation of instability, it can be a somewhat sluggish oxidizer.


I also agree he overwhelmed it with Al or expected results that demanded a serious excessive chlorine source. Some colors are tough anyway (as a "flash").
I think a guy will read so much about rich coloration of stars, etc and then have a concern that a flash should make at least something close......I think it's a natural assumption.

There was some studies of how the eye can become overwhelmed in perception with high intensity light & that may play a very big part in many experiments with color. Additionally, it's often daylight when the experiment is conducted; complicating it further with background and a pupil already constricted.



[Edited on 16-12-2010 by quicksilver]

Blasty - 16-12-2010 at 17:12

Quote: Originally posted by Mumbles  
If you're trying to make colors, why use aluminum? The purest colored flash powders are all made with magnesium for a reason. The aluminum oxide formed is a fairly decent white light emitter, which will wash out or over power any colorant that may be formed. You can get around this by a relative excess of chlorine to form aluminum chlorides, which are far more flame transparent. Magnesium oxide doesn't obscure visible colors nearly as much. I'm told it emits more in the UV, but I haven't looked at a spectra recently to check that out.

Some extra chlorine in the flame will ensure a greater concentration of the BaCl emitting species, which is the one you want. Otherwise you get some BaOH, amongst other things, which is more of a yellow-green to lime green color. Sulfur can help to generate free chlorine in a flame, but the chlorine is already where you want it when starting with barium perchlorate. If it behaves anything like barium chlorate, I'm not surprised it's underwhelming. For having the reputation of instability, it can be a somewhat sluggish oxidizer.


If you read older sources, like Davis, you will see that aluminum flash powders containing barium salts are reported as supposedly making a "green flash". Even nowadays you can still find aluminum flash powders that supposedly give such a green flash:

http://www.privatedata.com/byb/pyro/pfp/flash.html

Having tested several of these, it seems to me that the word "green" here is very relative. It's a very pale greenish tinge, actually, not what you initially expect if you have seen things that fit the definition of a "green flash" much better (like guncotton soaked in a barium perchlorate solution, then wringed out and dried.)

Tinkering with magnesium powder has a couple of problems:

1- It is not as easy to find as aluminum powders

2- It is reportedly more dangerous than aluminum

crazedguy - 16-12-2010 at 20:42

Magnesium is much more expensive so I never really planed to use it, I will just keep it simple with my regular flash. Which brings me to my next point we should have a video section.

Mumbles - 16-12-2010 at 23:51

I suppose I am a bit spoiled with my access to magnesium, so I always over assume it's ease of acquirement.

Unless you're using bright paint grade aluminums, it should be about as easy to acquire magnalium, which should offer an improvement in color. If not, it's not too difficult to manufacture, which shouldn't be much of a problem considering many here's insistence on ball milling aluminum foil.

As far as the pfp database, I only see one reference to a colored flash with aluminum, one by Wouter Visser. You will notice that all of the rest are composed of magnesium. I don't know who published the color flash powder formulae first, but the earliest I really know of is Degn, from the 1960's. Electric stars were known much earlier, and some may very well function as colored salute formulas.

Probably the most well known examples of colored salute mixtures is in the maltese beraq shells. All of the formulas use magnesium. While, as you mentioned magnesium is typically more reactive than aluminum, it functions the best. Lord knows there is no shortage of aluminum powder on the island. Be honest, colored flash powders are a niche composition typically reserved for exhibition. If you look at exhibition formulas from Davis, Weingart, etc. you will notice a distinct preference for color/effect over cost and safety. The same typically is used for these formulas. Even so, colored flashes are normally much weaker than a typical standard flash powder, so special techniques and more reactive formulas are used. If magnesium flashes would require brass balls, for the colored beraq formula/construction would require a stainless steel set which has been tempered and oil hardened.

It seems a bit odd to me that you are using barium perchlorate, but magnesium is too difficult to acquire and cost prohibitive.

[Edited on 12-17-2010 by Mumbles]

Blasty - 17-12-2010 at 02:17

Quote: Originally posted by Mumbles  
I suppose I am a bit spoiled with my access to magnesium, so I always over assume it's ease of acquirement.

Unless you're using bright paint grade aluminums, it should be about as easy to acquire magnalium, which should offer an improvement in color. If not, it's not too difficult to manufacture, which shouldn't be much of a problem considering many here's insistence on ball milling aluminum foil.

As far as the pfp database, I only see one reference to a colored flash with aluminum, one by Wouter Visser. You will notice that all of the rest are composed of magnesium. I don't know who published the color flash powder formulae first, but the earliest I really know of is Degn, from the 1960's. Electric stars were known much earlier, and some may very well function as colored salute formulas.


Check Davis, chapter on Chinese firecracker manufacture, where he already mentions green flash aluminum compositions (as he states, he got the info on such compositions from Allen F. Clark, who was apparently a pyrotechnist from Massachusetts.)


Quote:
I suppose I am a bit spoiled with my access to magnesium, so I always over assume it's ease of acquirement....

It seems a bit odd to me that you are using barium perchlorate, but magnesium is too difficult to acquire and cost prohibitive.


It seems we have a reverse situation here: for me it is easy to make this barium salt, since I have access to both barium hydroxide and ammonium perchlorate.

crazedguy - 18-12-2010 at 12:29

I have access to Aluminum and Magnesium its just that when Al is 6 dollars cheaper a pound, and I use pounds rather fast and Al produces the destructive power I am looking for Magnesium just never seemed like the powder for me.

quicksilver - 18-12-2010 at 12:44

Quote: Originally posted by Blasty  


Check Davis, chapter on Chinese firecracker manufacture, where he already mentions green flash aluminum compositions (as he states, he got the info on such compositions from Allen F. Clark, who was apparently a pyrotechnist from Massachusetts.)




Allen F. Clark did not truly publish (TTBoMK) but may have been the fellow who made the original very old film of "Chinese Firecracker Making". It's great that you brought up his name as I did a fairly in-depth search on that fellow as some years back I was VERY interested in the "Thousand Hex-Brick" hand manufacturing technique; using two bamboo tools and scrap paper. I actually DO have some leads on this but I don't want to pull this whole thread off in that direction. *


The true Ekart 5413 is not sold as "pyro" aluminum but the "5413-process" IS. The true Ekart material is incredible. It is what is known as an "ink-grade" pigment. Imagine what lengths a company would go to maintain a 2um size; no more and no less to produce a pigment fit for ink!

Please see the actual Ekart link:

http://www.eckart.net/products/aluminium-pigments/powder/pro...

* There ARE copies of that film! Again: to the best of my knowledge it was made during the "silent-film era", lasting approx 10-minutes (or less) & was said to have some written pre-projection script or text that was lost.


The BEST literature I have read on the subject of color was the Pyrotechnic Literature Series (especially #6), that was "Studies in Flame Colored Compositions" (Takeo Shimizu Part 3) If you can EVER get that: BUY it or copy it. As it has some of the most in-depth and complete works Mr Shimizu had done and was the culmination of his lecture series.
The complete set is no longer available as it was a $400 printed (transcribed lecture series sold by PGI or FWN private printing). Each lecture was $35 back in the day. The most difficult to find is 2/2 Report & Flash Composition Experiments. Genuine collector's material (I think there is 12 in total).






[Edited on 18-12-2010 by quicksilver]

Blasty - 18-12-2010 at 16:59

Quote: Originally posted by quicksilver  
Allen F. Clark did not truly publish (TTBoMK) but may have been the fellow who made the original very old film of "Chinese Firecracker Making". It's great that you brought up his name as I did a fairly in-depth search on that fellow as some years back I was VERY interested in the "Thousand Hex-Brick" hand manufacturing technique; using two bamboo tools and scrap paper. I actually DO have some leads on this but I don't want to pull this whole thread off in that direction. *


* There ARE copies of that film! Again: to the best of my knowledge it was made during the "silent-film era", lasting approx 10-minutes (or less) & was said to have some written pre-projection script or text that was lost.


Sounds interesting. What were you able to find out about both the man and the film? Davis' references to him are all about pyrotechnics, that's why I assume he was a pyrotechnist that Davis was personally acquainted with. Davis also mentions some of his brothers, one of them apparently with probable connections to the National Fireworks Company.

quicksilver - 19-12-2010 at 06:02

Please excuse this as being a bit OT but from what I found Clark was both an investor and involved with pyrotechnics in most every way a man could be before & during the 1920's. The company was one of his holdings I believe as was either the film or a series of materials that Clark wanted to make public. He was certainly a man who kept to his passion. I do not know if he had a scientific background per se' but he did document almost everything that he could re; pyrotechnics. Some mention of "War-time enterprises" made me think perhaps he was involved in WWI activities but in general, he was a great source to Davis & perhaps a personal friend.

The WiZard is In - 20-12-2010 at 09:33

Quote: Originally posted by quicksilver  

The BEST literature I have read on the subject of color was the Pyrotechnic Literature Series (especially #6), that was "Studies in Flame Colored Compositions" (Takeo Shimizu Part 3) If you can EVER get that: BUY it or copy it. As it has some of the most in-depth and complete works Mr Shimizu had done and was the culmination of his lecture series.

The complete set is no longer available as it was a $400 printed (transcribed lecture series sold by PGI or FWN private printing). Each lecture was $35 back in the day. The most difficult to find is 2/2 Report & Flash Composition Experiments. Genuine collector's material (I think there is 12 in total).


---------
Can be had from the publisher Journal of Pyrotechncs

http://www.jpyro.com/litseries/Shimizu/shimizu3.htm

Can be previewed at Google.com/books

Free from DTIC.MIL

1.
View TR Citation | View Full Text pdf - 510 KB
Title: RELATIONSHIPS OBSERVED IN COLORED FLAMES
Personal Author: Douda, B E
Corporate Author: NAVAL AMMUNITION DEPOT CRANE IN
Source Code: 247250
Page Count: 18 page(s)
AD Number: AD0607490
Report Date: 25 SEP 1964
Distribution Code: 01 - APPROVED FOR PUBLIC RELEASE
Report Classification: U - Unclassified
Collection: Technical Reports
2.
View TR Citation | View Full Text pdf - 2 MB
Title: Theory of Colored Flame Production
Personal Author: Douda, B E
Corporate Author: NAVAL AMMUNITION DEPOT CRANE IN
Source Code: 247250
Page Count: 68 page(s)
AD Number: ADA951815
Report Date: 20 MAR 1964
Distribution Code: 01 - APPROVED FOR PUBLIC RELEASE
Report Classification: U - Unclassified
Collection: Technical Reports
3.
View TR Citation | View Full Text pdf - 1 MB
Title: COLORED FLARE INGREDIENT SYNTHESIS PROGRAM
Personal Author: Douda, B E
Corporate Author: NAVAL AMMUNITION DEPOT CRANE IN
Source Code: 247250
Page Count: 44 page(s)
AD Number: AD0447410
Report Date: 10 JUL 1964
Distribution Code: 01 - APPROVED FOR PUBLIC RELEASE
Report Classification: U - Unclassified
Collection: Technical Reports
4.
View TR Citation
Title: Emission Studies of Selected Pyrotechnic Flames,
Personal Author: Douda,B E
Corporate Author: NAVAL AMMUNITION DEPOT CRANE IN
Source Code: 247250
Page Count: 25 page(s)
AD Number: ADA951839
Report Date: 04 AUG 1964
Distribution Code: 01 - APPROVED FOR PUBLIC RELEASE
Report Classification: U - Unclassified
Collection: Technical Reports

And a SL of other stuff.

The WiZard is In - 20-12-2010 at 14:03

Quote: Originally posted by crazedguy  
Quote: Originally posted by quicksilver  


If you want color - you generally need some chlorine. On occasion some of a lightest amount of parlon will yield some of the most brilliant coloration.
However the peroxides (as used in tracer composition) will get some fantastic color.

[Edited on 15-12-2010 by quicksilver]

Could you give more info on this or a source? For a while now I have been looking for a way to color my flash compositions, but as color I don't mean the burning I mean like the color of an M80 going off. Just haven't been able to find something that actually worked for that.



Sure —

The WiZard's Pyrotechnic Formulary
http://www.skylighter.com/ sells them. Though in my opinion
the price is a little high! Then he probably has sold more at his
higher price then I could at my lower price! Weird.

Extracted from la formulary. I have it in a DB (a DOS program!)
so I just extracted these.



SALUTE RED
DEGN LIPPY+PALDER
MAGNESIUM 50%
STRONTIUM/NITRATE 50

Salute green
Degn
Magnesium 10 pts
Barium/nitrate 10
PVC 1

SALUTE YELLOW
DEGN
MAGNESIUM 1 pts
SODIUM/OXALATE 1
POTASSIUM/PERCHLORATE 1

SALUTE VIOLET
DEGN
MAGNESIUM 10 pts
POTASSIUM/PERCHLORATE 10
CUPRIC/OXIDE 3
STRONTIUM/NITRATE 3
PVC 1

SALUTE BLUE
DEGN
MAGNESIUM 20 pts
POTASSIUM/PERCHLORATE 20
PARIS/GREEN 6
PVC 1

SALUTE WHITE
DEGN
MAGNESIUM 1 pt
POTASSIUM/PERCHLORATE 1

SALUTE VIOLET
DEGN PYROTECHNICA VI
STRONTIUM/NITRATE 8 pts
PVC 1
MAGNESIUM 16
PARIS/GREEN 8

Salute blue
Pyro-Tec
Potassium/chlorate 10 pts
Magnesium 13
Paris/green 7
PVC 1

Salute green
Pyro-Tec
Potassium/chlorate 3 pts
Magnesium 13
Barium/chlorate 10
PVC 2

The red works best, however, even then looking directly at it -
it is toooo bright. Reflected light looks the best.

None of these are safe. If they were safe they wouldn't work.
Keep the quantities mixed to a minimum or less.

MAJOR SOURCES FOR THE PYRO FORMULARY


AFN- American Fireworks News, Star Route Box 30, Dingmans Ferry PA 18328

ALLEN- An itinerant pyro Mr. Allen worked for a large number of companies, e.g., Rossi, Del Grande, Hitt, &c.. Everywhere he worked he collected formulae in his secret book. I have incorporated most of them in this compilation, eliminating those that were obviously wrong. There are, however, included a few that look possible, but not likely.

APFN- American Pyrotechnist Fireworks News Published October, 1970 to November, 1976.

BLESER RSS- David Bleser, Round Stars and Shells. Published by: American Fireworks News, Star Route Box 30, Dingmans Ferry, PA 18328.

CA- Chemical Abstracts vol##, ######

CHEMICAL FORMULARY- Chemical Publishing Co N.Y. Various Volumes. Vol. #1 1933.

CHEM LIT- A series of pamphlets on fireworks available from: Jim Saxon, 208 Franklin Blvd., Mahomet IL. 61853

CHEMPAC- A list of of formulae attributed to the now defunct Chempac Supply Co. They were probable copied from: James Cutbush's A System of Pyrotechny 1823.

BAECHLE Pch- Pyrocolor Harmony: A Designers Guide. Joel H. Baechle, 105 Erin Place, Jackson CA 95642.

DAVIS- Tenney L. Davis. The Chemistry of Powder and Explosives, 1943.

DENG- From a series of how-to's distributed by Westech 1970.
Chem

DICKS- Encyclopedia of Formulas & Processes 1872. In the PoorMan's James Bond.

ELLERN- Dr. Herbert Ellern. Military and Civilian Pyrotechnics, 1968.

ENCICLOPEDIA VNIVERSAL ILVSTRADA- 70 Vols. in Spanish, formulae from Vol. XLIV; Pirotechnia.

GREEN NOTES- Published by the now defunt Megatech Supplies, Myrtle Beach SC

HATCHERS NOTEBOOK- By Julian S. Hatcher. Stackpole Co. 1947. 3rd Ed. 1962.

HENLEY'S- Twentieth Century Book of Formulas, Processes and Trade Secrets. Publishers Agency Inc. 1937.

HI-LOW BOOM- Philip J. Danvisevich, 1966. Ken Hale Publications POB 395 McDonald OH 44437

KENTISH- Thomas Kentish, The Complete Art of Firework-Making 2nd Ed.

LANCASTER- Lancaster, Ronald, Takeo Shimizu, R.E.A. Butler, and R.G. Hall. Fireworks: Principles and Practice. 1972.

LIPPY AND PALDER- Modern Chemical Magic

MC- Fred L. McIntyre. A Compilation of Hazard and Test Data for Pryotechnic Compositions, 1980.

OP2793- NAVWEPS OP 2793 Toxic Hazards Associated with Pyrotechnic Items, 1963.

PGII BULL- Pyrotechnist Guild International Bulletin PGII Sec/tres Ed Vanasek, 18021 Baseline Avenue, Jordan, MN, 55352

PATR2700- The Encyclopedia of Explosives and Related Items. 10vols.

PYROTECHNICA- Pyrotechnica Publications, Robert G. Cardwell, 2302 Tower Drive; Austin, Texas 78703

RDTR 11- Experiments in Developing Green Flare Formulas.

RDTR 31- Investigation of Visibility and Formulation of Ashless Blue Flare.

RDTR 71- Spectral Analysis of Pyrotechnic HCl Emissions.

SHIMIZU- Takeo Shimizu, 1981. Fireworks: The Art, Science and Technique.

SHIMIZU 2- Takeo Shimizu, 1976. Fireworks: From a Physical Standpoint, Part II.

PYROTEKNIKDAGEN, Foredrqag vid. Swedish Pyrotechnic Conferences. Various years.

TECHNO-CHEM- Receipt Book of 1896. In the Poor Man's James Bond.

PSM- Book of Fourmulas: Recipes, Methods & Secret Processes. 1932.

TM1316- Survey of Sensitivity Characteristics of Typical Delay, Igniter, Flash, and Signal Type Pyrotech¬nic Compositions. 14pg. April 1964.

ULLMANN 4- Encyklopadie der technischen Chemie; 4th Edition.

USP- United States Patent #,###,###

WEINGART- George W. Weingart, Pyrotechnics, 1947.


As suggested comps used for tracer ammo will work. I can say from
experience that at least one will work!!! File them under HOT
SHIT
.



Blasty - 3-1-2011 at 06:08

Due to the usual New Year's fireworks mayhem around this area these past few days, I was able to further test these flash powder compositions with the fine atomized aluminum powder, this time confined in cardboard tubes, both home-made with Kraft paper + glue/paste and machine-made spiral tubes (such as used by pyrotechnists.) The tubes were about 2 to 2 1/2 inches long, with a bore of about 1/4 of an inch and a wall thickness of about 1/16. I employed the "can test" method to get an idea of the "striking" force of the mixtures. This basically consists in putting a measured charge of the composition inside such tubes, and then inserting it inside a metal can, such as a soda or juice can. But I don't mean the flimsy aluminum cans commonly used in the US for such products, but those still used for sodas and juices in some countries, specially in Latin America and Asia, like these coconut water cans that you can find in the international section of many supermarkets:

http://www.philamfood.com/images/P/0016229901479.jpg

These are actually made of steel sheet and it takes much more force to break through them (the flimsy American aluminum soda cans are easily ripped apart even by 1 gram charges of a good fast black powder.) For safety reasons, a hole is dug up in the ground and the can with the charged tube is placed in it before setting it off, just in case the explosion is too violent and throws any shrapnel around. Charges not exceeding one gram were used.

This was only a preliminary set of tests, which would need to be repeated more times, which I might do later on. The results can be summarized as follows:

In both the home-made and machine-made spiral tubes the nitrate and sulfate flash powders just blew the hot glue end plugs and did not burst the tubes. In this sense, they behave like black powder: they seem to need very strong confinement for such a thing to happen. This strong confinement was achieved in the same manner that I use for making black powder burst through such cardboard tubes without blowing the plugs: by drilling 4 opposing holes about 5mm from each end of the tube and injecting the hot glue through them. This gives a very strong seal.

The sulfate and nitrate mixtures did not function well in the home-made tubes. They tend to rip apart only one side of the tube (the "upper" side; the tubes are laying down horizontally inside the cans.) In this sense, these flash powders seemed again to behave like black powder confined in the same tubes. In the machine-made spiral tubes a bursting of all the tube was achieved. However, not even 1 gram of such mixtures were able to appreciably dent the steel sheet body of the cans. The lids of the cans were blown off or severely dented, but the strongest part of the can (its "body") was pretty much left intact. These flash powders still give a very loud report. 1 gram of the barium sulfate mixture gives a sharp and loud report, but, as already pointed out, it has to be strongly confined for it to perform at its best (the claim that this mixture "makes a nice noise in open tubes" does not seem to be true, at least not when using fine atomized aluminum.)

The mixtures containing perchlorates worked well even in the home-made tubes, and they did not need specially strong confinement, normal hot glue plugs worked just fine. The old firecracker mixture reported by Davis (which he got from Clark) of equal parts sulfur, aluminum, barium nitrate and potassium perchlorate seemed to be the strongest of the ones tested. 0.8 g of it not only blows the lids of the cans but gives a plainly noticeable dent to its body. Needless to say, it gives a sharp loud report.

The observation by Davis that the flash powders containing chlorates and perchlorates are "fulminating explosives when confined" (as opposed to those that do not contain them) seems thus to be accurate.

[Edited on 3-1-2011 by Blasty]

hissingnoise - 3-1-2011 at 07:34

Mixtures with alkali nitrates as oxidiser seem incapable of fulminating - according to Davis, black powder has never been known to do anything but burn!
But lightning is the root of the word "fulminate" and thunder the root of "detonate" . . .
Without the alien it's "donate"!



prometheus1970 - 31-1-2011 at 21:17

Isuppose what I should have made clear when I originally posted this question is that I'm wondering if flash powder ever undergoes DDT. Does flash powder detonate when ignited by spark, spitting flame, fuse etc.,whether confined or in masses of sufficient quantity?

[Edited on 2-1-2011 by prometheus1970]

quicksilver - 1-2-2011 at 09:03

70/30 flash has a 50 gram threshold of self confinement (Konski lecture series on Flash Attributes & Measurements). That's a damn rough figure but he was dealing with pyrotechnic applications and related measurements were fairly casual.

A Flare mfg site in Henderson NV had a terrible explosion resulting in one or more fatalities from their standard of KCLO4, Al, and a NC binder back some years ago. Flash is vicious due to a variety of reasons. One of them is that the Al becomes airborne and more easily subject to static. That's why one of the best improvements was to use enclosed tubes to distribute the materials; eliminating open containers and gravity mixing instead of contact mixing.

Blasty - 17-4-2011 at 11:11

Quote: Originally posted by Blasty  
Quote:
The ratios are Barium Sulfate 6, Aluminum (Dark Pyro) 3, Sulfur 1.


I recently tested this mix to see how it burned. Instead of using dark pyro aluminum, though, I used atomized (spherical) aluminum but in very fine powder (3000 mesh.) The thing is quite difficult to ignite, but once it does it flashes nicely. Sometimes the regular visco fuse I use just runs right through a small pile of the powder without igniting it (the ejecting gases from the fuse tend to scatter the flash powder and do not give it enough time to get hot enough for it to ignite.) A slower burning fuse helps avoid this from happening. Putting a little bit of granulated black powder on this mix it ignites readily even with the faster fuse.



I just finished some tests on this mixture but using strontium sulfate instead of the barium one. It is even harder to ignite. Not even putting a heap of black powder on it ignited it. The only way I managed to ignite it is by putting the flame of a butane lighter-torch on it until it was glowing orange-white for a while, then all of a sudden it ignited with a quick bright flash and a loud "THUMP!" If this mixture could be ignited a bit more easily it would make a very good and safe flash powder.

quicksilver - 17-4-2011 at 11:38

There is a fascinating phenomenon that takes place in deflagration where the particulate gets smaller and smaller. Magnesium is a very good example. There is a point where the smaller particulate can "cake" or compress to such a degree that ignition becomes more difficult instead of easier. The demand for oxygen between the particulate (for flame initiation) reaches a point where one is almost attempting to "ignite a solid" unless the material is "fluffed" or brought to a point where oxygen can access the composition. Flame initiation is decidedly different that initiation via a detonation in extremely fine particulate. That threshold will differ in various compositions but it will exist in many, if the particulate is in the single micron (2-9um) size.

dann2 - 17-4-2011 at 14:20


I often wondered what the effect would be if a relatively large quantity of some flash composition was subjected to a long exploding wire(s).
If, say, a quanity of flash that was 4 inches by 4 inches had a number of thin wires threaded through it's bulk and all these wires were energised at the same moment (+ - some tens of mircoseconds) then 'all' of the flash would be 'going off' throughput it's bulk as opposed (if initiated with a flame) to travelling from one side/end to the other side/end.
Would this not have the effect of increasing 'the brisance' of flash my a large order?

Not pyro related I guess.

Dann2

quicksilver - 18-4-2011 at 06:05

Blasty:
I accidentally lost your comment it responding to it: apologies. But it DOES explain the Cab-o-sil issue indeed. You were right on track (IMO). Yes. anti-caking agents really DO have a positive affect. As do the use use of "spread" size spectrum ingredients. Whenever exampling a deglagration of DDT element, especially in a mechanical composition, you will see this agenda often raise it's head.

Bot0nist - 18-4-2011 at 06:21

I think that was my comment. Thanks though. That's what I had always assumed. Kind of counter intuitive when thinking about density and explosive propagation.

quicksilver - 18-4-2011 at 09:39

Sorry, It was early in the morning and I was rushing around typing & looking at the clock.
I believe it was Konski (sp?)who either wrote and / or spoke of the need to work against materials compacting into a near solid due to particulate size. His example was rice hulls used in burst charges for entertainment fireworks but I supposed you could extrapolate that to most any per/chlorate flame initiated composition.
Personally, I have seen this myself. My personal experience was w/ magnesium. I had seen a design of a pyrotechnic that was fairly interesting (photographic flare genre') in that it used a two layer design similar to a Class B entertainment firework.
The thing had a burst charge made simply within a strong enclosure. The inner most layer containing a burst charge; the outer, containing extremely fine magnesium. The idea being that the burst charge would distribute the finely powdered metal in a small scale air-fuel explosion.
The technique was complicated by several factors. One of which was that the finely powdered metal alone often didn't ignite that well. It needed to be kept from compacting. The burst charge needed to be slow and substantially "flame-imbued". Black powder was actually the best form of burst charge as it spread a substantial amount of flame & was slow enough to allow the metallic particulate to spread just enough to catch.
The result for a SMALL design (3 grams - 1x3" outer tube; 1/4 x 2" inner) made a substantial blast, providing enough light to illuminate at lest 700 sq ft. It was very entertaining: the "fire ball" was about 15 sq ft and the noise was of low frequency & unique. Without a "fluffer" the metal would never spread to desired area. Rice hulls do very well with Al but Mg was best when interspersed with larger particulate of Mg, pyrophoric lead salts and cab-O-Sil. From an entertainment standpoint the noise and flash were very gratifying from a device that small.

Bot0nist - 18-4-2011 at 10:47

That sounds extremely beautiful.

*Runs to his workshop, inspired*

I also use BP coated hulls or hay for my burst charges. It always seems to give a better spread and I nice thump. I have never experimented with a magnesium dust cloud. Sounds amazing.

Quote:
providing enough light to illuminate at lest 700 sq ft.

The WiZard is In - 18-4-2011 at 12:57

Quote: Originally posted by quicksilver  
Blasty:
I accidentally lost your comment it responding to it: apologies. But it DOES explain the Cab-o-sil issue indeed. You were right on track (IMO). Yes. anti-caking agents really DO have a positive affect. As do the use use of "spread" size spectrum ingredients. Whenever exampling a deglagration of DDT element, especially in a mechanical composition, you will see this agenda often raise it's head.

Cab-O-Sil has always worked for me, and when it worked it worked
well. I would posit three reasons —

It it v/ very hard and not compressible thus creating interstitial
space through which the flame can propagate.

Its specific heat is high enough that it helps transfer heat through

the comp.

I have found that when it is added in small %'s if the case is
tapped on a hard surface ... 5-10% more comp can be loaded
into the case.

These from the late Dr. Shimizu's Fireworks From A Physical
Standpoint, a translation from the German by Alex Schuman
of Feverwerk von physikalischem Standpunkt aus (1976).
Published in four parts by Pyrotechnica Publications, 1981.

With a little simple math you can calculate the IS of spheres. To
find it in layered spheres ... a bunch of ball bearing or some such
and a graduated cylinder would enable on to derive a formula to
calculate it for different size spheres. For the truly driven it can be
approximated by mercury porosimetry.

NB - Dr, Shimizu's comment about large particle black powder
burning faster ... only works in open systems... thus cannon use
large particle BP, rifles/pistols faster burning small particle BP.




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quicksilver - 20-4-2011 at 07:22

Good point; also an excellent example.

Particulate hardness properties are a valuable topic in themselves. Mg is decidedly harder that Al (thus the flaking in Al, granularity in Mg). The Cab-O-Sil hardness and size property is a valuable addition to a great many materials.
Flash has still some "undiscovered country" in it's make-up and utility. When efforts were made to maintain the shift of commercial Flash to the standard 70/30 there were those who continued to use a temperature lowering agent(s) such as sulfur (or a sulfide) in the hopes that increased flame sensitivity would provide a faster combustion spread. It was thought that this faster combustion aided simple report utility in sound-oriented pyrotechnics.
It would seem that Konski (sp?) may have blurred the concept by his discussions of the use if Ti (& some other additions) and their [lack of] effect on sound volume. (See presentations of flash power sound levels; PGI Series '96) It would seem that Shimizu may have been correct in his assertions that compositions w/ a third temp-oriented component were louder.


RIP: Takeo Shimizu 1912-2011 Died in February of this year at the age of 98. Began work in pyrotechnics in 1951 until his death by natural causes. Was said to have spoken more than half a dozen languages & continued with Koa Fireworks / Japan until his passing.

The WiZard is In - 20-4-2011 at 09:30

Quote: Originally posted by quicksilver  
It would seem that Shimizu may have been correct in his assertions that compositions w/ a third temp-oriented component were louder.

RIP: Takeo Shimizu 1912-2011 Died in February of this year at the age of 98. Began work in pyrotechnics in 1951 until his death by natural causes. Was said to have spoken more than half a dozen languages & continued with Koa Fireworks / Japan until his passing.

Yes. Dr. Shimiz's Thunder #3 gets my vote.

Also - never underestimate the advantages that can be had
by good containment ... well not that good — think
fireworks not infernal devices.

Heavy walled - parallel wound tubes work wonders for output.

Flash compositions of some types will cause explosions in the
lightest of containers even sometimes in just a few turns of paper
but it also happens that these compositions are extremely brisant
and sensitive. Horrifying mixtures of potassium chlorate, pyro
aluminium, sulphur and barium nitrate have been employed and
should be avoided at all costs. Mixtures of the perchlorate, sulphur
and bright aluminium are safer and appear to be used extensively
in the U.S.A. and Japan, but even these would be considered
dangerous by many of us in Europe. In fact the more common
European technique is to use a strong paper tube with a
composition consisting simply of potassium perchlorate and dark
pyro aluminium.


Ronald Lancaster Fireworks: Principles and Practice


In memoriam Dr. Takeo Shimizu

When beggars die there are no comets seen;
The heavens themselves blaze forth the death of princes.

Calpurnia


Blasty - 20-4-2011 at 16:30

Quote: Originally posted by The WiZard is In  
Also - never underestimate the advantages that can be had
by good containment ... well not that good — think
fireworks not infernal devices.

Heavy walled - parallel wound tubes work wonders for output.

Flash compositions of some types will cause explosions in the
lightest of containers even sometimes in just a few turns of paper
but it also happens that these compositions are extremely brisant
and sensitive. Horrifying mixtures of potassium chlorate, pyro
aluminium, sulphur and barium nitrate have been employed and
should be avoided at all costs. Mixtures of the perchlorate, sulphur
and bright aluminium are safer and appear to be used extensively
in the U.S.A. and Japan, but even these would be considered
dangerous by many of us in Europe. In fact the more common
European technique is to use a strong paper tube with a
composition consisting simply of potassium perchlorate and dark
pyro aluminium.


Ronald Lancaster Fireworks: Principles and Practice


Indeed, I can attest to this. The perchlorate flash powders even work well with Kraft paper home-made tubes, while the nitrate and sulfate flash powders not so much. But if you strongly enclose these non-perchlorate mixtures in those professional pyro tubes they deliver a great report.

Mumbles - 22-4-2011 at 21:54

There was some experimentation going on with the sulfate based powders several years ago by a few people I am acquainted with. The production of several pounds of flash for large bottom shots and canister shells makes some people uneasy understandably. I believe they had the best luck with larger salutes using an initiating charge of a more typical flash powder, such as 70/30. As has been found, they never had great luck with smaller salutes. I don't recall if they ever tried something intermediate in size, say 1" ID x 2.5" long as would typically be used as salute inserts in some shells.

Blasty - 23-4-2011 at 14:30

Quote: Originally posted by Mumbles  
There was some experimentation going on with the sulfate based powders several years ago by a few people I am acquainted with. The production of several pounds of flash for large bottom shots and canister shells makes some people uneasy understandably. I believe they had the best luck with larger salutes using an initiating charge of a more typical flash powder, such as 70/30. As has been found, they never had great luck with smaller salutes. I don't recall if they ever tried something intermediate in size, say 1" ID x 2.5" long as would typically be used as salute inserts in some shells.


Barium sulfate flash powder (6 barium sulfate, 3 very fine atomized aluminum, 1 sulfur + a bit of black powder to help ignition) in 1 gram charges inside strongly sealed pyro tubes (1/4" ID x 2-1/2" long.) The report is very loud.

[Edited on 23-4-2011 by Blasty]

Mumbles - 23-4-2011 at 17:32

How fine is fine? Less than 5 micron?

I could definitely see sulfur making a difference. I don't think they were using any axillary fuels.

[Edited on 4-24-2011 by Mumbles]

pjig - 23-4-2011 at 20:53

I put a test batch together tonight, and the mix was made with German dark flake 5micron Aluminium and B-sulfate ..

The result was a very bright green-white slow burning mix (Slower than B.P.), nothing I'd associate to flash's energetic burn .. I'd have to say that copper oxide flash/thermite is by far much more energetic.

**Is this normal , or is something off here?

I have in past made the B-sulfate flash with out the sulfur , and it failed to burn energetic......maybe the ratios where off (like 1 to1), I dont remember, but it just smoldered and left behind a solid ball of molten Aluminium. The sulfur really helps lower the temp of the ignition.

Neat stuff though ....

[Edited on 24-4-2011 by pjig]

pjig - 23-4-2011 at 22:23

Ok after satisfying a second idea...., I used a piece of quick match to ignite the B-sulfate flash ,and what a difference !!!! It reacted like flash and went with a thump.... I now realize another fellow claimed this in a earlier post.He stated that the mix needs a boost to get to the needed temps for it to react like a flash mix.

I'd post a short vid. but it is in 3g format and my software is old and refuses to let me get it converted to windows media format.
Next time Ill use my dig cam ... w:)

Blasty - 23-4-2011 at 22:25

Quote: Originally posted by pjig  
I put a test batch together tonight, and the mix was made with German dark flake 5micron Aluminium and B-sulfate ..

The result was a very bright green-white slow burning mix (Slower than B.P.), nothing I'd associate to flash's energetic burn .. I'd have to say that copper oxide flash/thermite is by far much more energetic.

**Is this normal , or is something off here?

I have in past made the B-sulfate flash with out the sulfur , and it failed to burn energetic......maybe the ratios where off (like 1 to1), I dont remember, but it just smoldered and left behind a solid ball of molten Aluminium. The sulfur really helps lower the temp of the ignition.

Neat stuff though ....


Never tried it without the sulfur. With it it works very well, though, except that it still is a bit difficult to ignite.

[Edited on 24-4-2011 by Blasty]

Blasty - 23-4-2011 at 22:34

Quote: Originally posted by Mumbles  
How fine is fine? Less than 5 micron?

I could definitely see sulfur making a difference. I don't think they were using any axillary fuels.

[Edited on 4-24-2011 by Mumbles]


I use 3000 mesh atomized aluminum powder. This one:

http://www.alphachemicals.com/aluminum_powder

Works very well with other oxidizers too. Seems more insensitive at first than dark pyro aluminum (which makes it safer to handle and mix, IMHO), but once it gets ignited it reacts very fast due to the very small particle size.

The WiZard is In - 24-4-2011 at 15:36

Quote: Originally posted by Mumbles  
There was some experimentation going on with the sulfate based powders several years ago by a few people I am acquainted with. The production of several pounds of flash for large bottom shots and canister shells makes some people uneasy understandably. I believe they had the best luck with larger salutes using an initiating charge of a more typical flash powder, such as 70/30. As has been found, they never had great luck with smaller salutes. I don't recall if they ever tried something intermediate in size, say 1" ID x 2.5" long as would typically be used as salute inserts in some shells.

Some years back in an attempt to make a fountain I put
a 'hole bunch of K perchlorate and fitter (really large
flake) aluminium in a 3" of so cardboard tube from the supermarket
that still had 3" of that thin plastic wrap they use on meat trays
&c., wrapped around it. Indestructible sez I. Put couple of ounces
on 2FA in as lift .... Back off .... Watch this .... a tremendous
KABOOM you could feel in your gut with a flash so bright that had
the Space Shuttle been overhead they would have seen it. La
cardboard tube? Nowhere to be found.

This in an open ended tube. Never underestimate the pyrotechnic
advantage of a good kick in the ass.

quicksilver - 24-4-2011 at 16:49

Unfortunately some folks think "containment" means a total encasement of an energetic material; such is not the reality. Even slower deflagrants
(nitrate based & similar) can occasionally pop with an open end.


Very few rocket hobbyists forget their first CATO.

[Edited on 25-4-2011 by quicksilver]

Blasty - 24-4-2011 at 22:54

Quote: Originally posted by quicksilver  
Unfortunately some folks think "containment" means a total encasement of an energetic material; such is not the reality. Even slower deflagrants
(nitrate based & similar) can occasionally pop with an open end.


Very few rocket hobbyists forget their first CATO.


I find it quite difficult to make sulfate/nitrate flash powders and black powder "pop" unless strongly confined. They tend to just blow the lids/plugs of the container if they are not strongly fixed in place, instead of bursting the container to pieces. An excellent way to assure that the plugs are not going to be blown off is to drill 4 opposing holes close to the ends of the pyro tubes and inject the hot glue through them. This produces a very strong plug. Even 1 gram of black powder can be made to deliver a respectable bang this way.

Flash powders containing perchlorate do not need the same degree of containment. A simple hot glue plug will do.

quicksilver - 25-4-2011 at 06:12

Mechanical mixtures often depend on the consistency of their physical intimacy (closeness of particulate to one another) for their effectiveness. That's why commercial BP is always so much more effective than most home made types.....The end user just doesn't have the facilities to get the particles in such proximity as a plant-level mixing.
If a VERY fine particulate is made from the base oxidizer (perchorate, etc) and an equally fine level of fuel / reducing agent is mixed to a high level of intimacy, the flash will have little trouble making a report from a simple folded piece of paper. The simple "triangle design" fold is often an ample test to determine this & that flash powder will self contain at 50 grams (below a 2 oz level).
There was a safety concept of placing the composition into the container one item at a time and then providing a method of shaking or vibrating to mix when contained to avoid handling the composition, prior. This never worked as well unfortunately even in plant operations with quality design.


Microscopic measurement of perchlorate particulate reduced in size through the use of a "coffee grinder" was found to be very close to single micron size (2-9 um) via empirical observation (slide measurement utility).

[Edited on 25-4-2011 by quicksilver]

Blasty - 25-4-2011 at 09:53

Quote: Originally posted by quicksilver  
Mechanical mixtures often depend on the consistency of their physical intimacy (closeness of particulate to one another) for their effectiveness. That's why commercial BP is always so much more effective than most home made types.....The end user just doesn't have the facilities to get the particles in such proximity as a plant-level mixing.
If a VERY fine particulate is made from the base oxidizer (perchorate, etc) and an equally fine level of fuel / reducing agent is mixed to a high level of intimacy, the flash will have little trouble making a report from a simple folded piece of paper. The simple "triangle design" fold is often an ample test to determine this & that flash powder will self contain at 50 grams (below a 2 oz level).
There was a safety concept of placing the composition into the container one item at a time and then providing a method of shaking or vibrating to mix when contained to avoid handling the composition, prior. This never worked as well unfortunately even in plant operations with quality design.


Microscopic measurement of perchlorate particulate reduced in size through the use of a "coffee grinder" was found to be very close to single micron size (2-9 um) via empirical observation (slide measurement utility).


The black powder I make (using air float charcoal, and ball-milling for 24 hours) is about as well mixed as I think it will ever get. After granulating, it burns in a quick flash with a loud "whoosh!". And you still need a strong plug to reliably make it burst the container to pieces, not just violently shoot the plug/lid out. Most of the time normal hot glue plugs will just be shot out. Another effective method is what I call "the medieval way" (after Marcus Graecus' description of the firecrackers of his times): make a paper tube and strongly tie the ends shut.

The nitrate and sulfate flash powders using the exact same sulfur and aluminum powder as the perchlorate ones, and mixed the same way (viz. tumbling/diapering the powders), still need stronger confinement to work in the best manner. Otherwise they will also tend to just blow out the plugs. With the perchlorate flash powders you can even just use home-made Kraft paper tubes & simple hot glue plugs and get a heck of a bang.

quicksilver - 26-4-2011 at 07:05

You might have come as close to commercial-level as is possible without a ten-ton stone wheel or some crazy thing like that. When I make something with BP I also remind myself that generally almost half (about 46%) of the material is converted into solids in the smoke elicited from it's burning. This is often not wasted but allows the "gas" to have a degree of pressure behind it in a confined space design. However that is a very good example of when the design needs to be a full enclosure.

Explosive wave patterns and strength have been studied (L. Walt and Cooper) & if speed were dismissed, some materials explosions have very powerful "breaking fronts" in that they are able to do work that is not accomplished by many "faster-than-sound speed" blast waves can achieve. I always thought this was fascinating & I believe it was one of the reason why BP was used in blasting for centuries. Unfortunately these studies have never been preformed on per / chlorate type mechanical-compositions explosives. The strength on a small to moderate scale leads me to think that they too have a vast amount of solids in their released gas & that may be one of the reasons why they are SO powerful per unit weight.


I was trying to find a picture (now long gone) of a motor that pushed a BP rocket well beyond what I had done with a smaller (D -?) motor with ammonium perchlorate.

[Edited on 26-4-2011 by quicksilver]

Mumbles - 26-4-2011 at 22:11

Quote:
I use 3000 mesh atomized aluminum powder. This one:

http://www.alphachemicals.com/aluminum_powder

Works very well with other oxidizers too. Seems more insensitive at first than dark pyro aluminum (which makes it safer to handle and mix, IMHO), but once it gets ignited it reacts very fast due to the very small particle size.


In a not all that scientific study done by Ken and Bonny Kosanke, they found a similar aluminum was even more powerful than the more traditional dark flakes. If one were to believe their results, it would make sense that more powerful = more sensitive. I think dark flake Al flashes are less sensitive than some lead on to be.



Quote:
Mechanical mixtures often depend on the consistency of their physical intimacy (closeness of particulate to one another) for their effectiveness. That's why commercial BP is always so much more effective than most home made types.....The end user just doesn't have the facilities to get the particles in such proximity as a plant-level mixing.


I'm going to have to disagree with this statement. Commercial powders are based on consistency, not ultimate strength. It is a fairly simple feat to make powders at home that easily outpreform commercial BP. I suppose it depends what you mean by "effective", but in a scenario such as lifting or breaking shells it's quite an easy feat.

Related to this, in another post, the large wheel mills do no actual grinding of particles. Everything is pre-milled in large ball mills. The wheel mills kneed the dampened powder together. Achieving a similar level of particle size of individual chemical in a homemade ball mill is probably very approachable, though likely not as quickly as one could do so with a 10ft diameter mill.


Quote:
The nitrate and sulfate flash powders using the exact same sulfur and aluminum powder as the perchlorate ones, and mixed the same way (viz. tumbling/diapering the powders), still need stronger confinement to work in the best manner. Otherwise they will also tend to just blow out the plugs. With the perchlorate flash powders you can even just use home-made Kraft paper tubes & simple hot glue plugs and get a heck of a bang.


Do you not feel comfortable screening said mixtures for some reason? Commercially when making flash, as well as all prominent shell builders, regularly screen all of their flash. It is typically of a KClO4/Al, or KClO4/Al/S mix. There is no other way to safely make large batches, nor get the mixture as intimately mixed. There is a noticable difference between something screened vs. just diapered. As a very well regarded pyro, Mike Swisher, once so elequently put it; Diapering is for babies.

Adding the individual chems to a casing and relying on handling the device during spiking, pasting, finishing, etc is generally regarded as the binary method. It's really only acceptable for ground salutes or rockets. Neither are things I have much interest in (each for different reasons). Doing something like that for shell inserts or bottom shots is actually quite dangerous. It makes shells much more likely to flower pot. In the days of handfiring, this is about as devastating as it could get.



Blasty - 26-4-2011 at 23:58

Quote: Originally posted by Mumbles  

In a not all that scientific study done by Ken and Bonny Kosanke, they found a similar aluminum was even more powerful than the more traditional dark flakes. If one were to believe their results, it would make sense that more powerful = more sensitive. I think dark flake Al flashes are less sensitive than some lead on to be.


I think that even the aluminum of commercial firecrackers (which is not dark pyro) is easier to ignite than this fine atomized aluminum. Even in mixtures with perchlorate and sulfur you can still notice that it's a bit difficult to ignite. Don't get me wrong, this stuff gives a fast reaction once it ignites, but the thing is to get it ignited first. But I might double-check this by preparing a small sample of the aforementioned strontium sulfate flash powder with dark pyro aluminum (I still have a can of it somewhere around) and see if it ignites more readily than with the fine atomized aluminum (it couldn't be any harder; the sample I prepared with this atomized aluminum had to be heated with a lighter-torch until it was glowing for a while before it went off.)


Quote:
Do you not feel comfortable screening said mixtures for some reason? Commercially when making flash, as well as all prominent shell builders, regularly screen all of their flash. It is typically of a KClO4/Al, or KClO4/Al/S mix. There is no other way to safely make large batches, nor get the mixture as intimately mixed. There is a noticable difference between something screened vs. just diapered. As a very well regarded pyro, Mike Swisher, once so elequently put it; Diapering is for babies.


I do not prepare large quantities of it, so I do not resort to screening. Diapering/tumbling gives good enough results in smaller batches. Large quantities of flash powder are very scary, even the safer ones, like the sulfate-based powders, would make me uneasy in large quantities.

quicksilver - 27-4-2011 at 08:19

I tried to be pretty careful with my verbiage: "consistent" is something I would go with. But yet I believe that the level of consistency of commercial BP (IF we confine that to 75/15/10) would still have an edge on home made in more than just consistent make-up. Proper corning is something that a guy has a tuff time with making that would top commercial in a utilitarian perspective.
I'd say this; if it absolutely has to be presenting a specific burn rate, etc. Commercial has the edge. IF we are looking for a 75/15/10 that is simply faster burning than a ffff, I agree someone could do it without plant-level apparatus.

But this is all subjective anyway.

I DID see one of the best mixing utilities for flash in a long time, that someone made. They took an old electric toothbrush (battery powered) and placed a piece of plastic tubing about 12" long ( approx 1/4" ID) on the tip and it vibrated remarkably well. It also did not seem to store static energy. When the composition was placed in a contained (ceramic for lack of conductivity) the end of the tube was placed within. The vibration was so minute and fast, it mixed it with amazing rapidity (& very well) that it was completely mixed in a pretty damn safe manner.
I have experimented with diapering and never got a really good mix & settling had been a problem. This technique kept any static from building and the tube vibrated SO fast but in very tiny increments, that it did a better job than most methods.


[Edited on 27-4-2011 by quicksilver]

quicksilver - 15-9-2011 at 13:01

Quote: Originally posted by Mumbles  


In a not all that scientific study done by Ken and Bonny Kosanke, they found a similar aluminum was even more powerful than the more traditional dark flakes. If one were to believe their results, it would make sense that more powerful = more sensitive. I think dark flake Al flashes are less sensitive than some lead on to be.



There is more to this than many know. The use of powdered Al in Mil-spec applications is not "dark pyro"
Powdered Mg, although it does not flake, is often less reactive once it gets lower (smaller) than a certain optimum size. But that's another story: the particulates often fit together like a puzzle and become more difficult to ignite when not used as an air-float but in a standing solid.

In any grouping of size in Al there is often very tiny particulate, far smaller than the average (325 mesh will often contain a substantial percentage of 2um, etc). Therefore in large military-industrial applications the idea of using "dark-pyro" is a serious waste of funds. Ekherk provides it's products for inks and goes to a great deal of trouble to make it sizing consistent. It's actual cost is very high when compared to actual industrial Al flake in bulk.

Realistically an adulteration one-to-five use of a "dark-pyro" Al in 325 bright flake is more than appropriate for pyrotechnic use. And that 6 pound end-product has often been used as the examination of many bulk sales has shown that to be a realistic ratio of single micron size within non-specialized Al powders.
Ekhert powders was originally designed for inks and finishes (due to the effort toward consistency in size) and only later in their company's history did they manufacture a "pyrotechnic oriented" product line. Please see Ekhert's web site for additional information in product line application & design.




[Edited on 15-9-2011 by quicksilver]

testimento - 11-7-2013 at 22:39

Could a chlorate based petroleum exlosive be initiated with a decent flash-powder-based or ammonium perchlorate based metal composition charge utilized as a detonator?