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prometheus1970
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[*] posted on 16-10-2010 at 13:02
Flash powder detonation


\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




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[*] posted on 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."


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prometheus1970
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[*] posted on 16-10-2010 at 17:56


Thanks, that helps...



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[*] posted on 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]
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[*] posted on 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.

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[*] posted on 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.
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[*] posted on 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.
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[*] posted on 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




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[*] posted on 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]
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[*] posted on 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]
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[*] posted on 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.
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[*] posted on 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]
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[*] posted on 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)
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[*] posted on 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.



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[*] posted on 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.
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[*] posted on 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]




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[*] posted on 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


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[*] posted on 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]




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[*] posted on 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]
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[*] posted on 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.
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[*] posted on 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]




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[*] posted on 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.
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[*] posted on 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?!?!]
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[*] posted on 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.
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[*] posted on 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]




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