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prometheus1970
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[*] posted on 14-7-2011 at 15:45
black powder ammonia smell


I was making a batch of black powder. Rather than ball milling it, I make a soln. with the proper amount of KNO3, then soak my charcoal powder with that then let it dry. This time I added some Eckhart 5413 to the mix to make it sparkly. After awhile I noticed a rather strong ammonia smell emanating from the batch. I could even see vapors rising from the mush. I cannot think of any way I could get either NH3 or NH4OH from a mixture of charcoal, KNO3, H2O: and Al powder. The KNO3 has been kept in an airtight container and is about 5 years old. The mixture is in a sauce pot (most likely aluminum, with spots of teflon coating missing). Any ideas what is happening?

[Edited on 7-15-2011 by prometheus1970]




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[*] posted on 14-7-2011 at 15:49


Aluminum is able to reduce Nitrates all the way to ammonia. Somehow there was a reaction able to take place effecting this reduction.




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[*] posted on 14-7-2011 at 16:45


Quote: Originally posted by prometheus1970  
I was making a batch of black powder. Rather than ball milling it, I make a soln. with the proper amount of KNO3, then soak my charcoal powder with that then let it dry. This time I added some Eckhart 5413 to the mix to make it sparkly. After awhile I noticed a rather strong ammonia smell emanating from the batch. I could even see vapors rising from the mush. I cannot think of any way I could get either NH3 or NH4OH from a mixture of charcoal, KNO3, H2O: and Al powder. The KNO3 has been kept in an airtight container and is about 5 years old. The mixture is in a sauce pot (most likely aluminum, with spots of teflon coating missing). Any ideas what is happening?


Any ideas what is happening? Sure what is
supposed to happen....

Introduction

EXPLOSION HAZARDS OF PYROTECHNIC ALUMINIUM COMPOSITIONS

Stig R Johansson and K Goran Persson
Industrial Laboratories,
The Swedish Match Co , Jonkoping
Föredrag vid PYROTEKNIKDAGEN [Pyrotechnic Day] 1971


The small scale handicraft production of generator-gas matches and
other pyrotechnic items based on aluminium containing compositions takes
place occasionally, for instance, in some match factories An explosion
which occurred on the 7th of May 1970 in connection with manufacture of
this kind brought into focus the question as to whether self-ignition and the
subsequent detonation of pyrotechnic aluminium compositions are possible
on the whole.

The high reactivity of aluminium powders is utilized, inter alla in
thermite reactions, explosives, and propellants, but very little can be found
in literature about fire and explosion hazards, especially as far as
aluminium compositions are concerned (cf ref 1, p. 328)

The course of events of the present accident was as follows. At the
end of the day before (i.e., the 6th of May) a stainless steel bucket
containing about 12 kg residual aluminium composition was placed in water
in a vat without being fully immersed, The composition was covered by a
layer of water, and in addition a loose lid was placed on the top of the
bucket.

On the following day, which was a holiday, an explosion occurred in
the afternoon. The explosion resulted in considerable structural damage to
the building, as is shown by the picture in figure 1. Fortunately, nobody was
in the area.

After the place had been cleared an impact mark could be seen in the tiled
floor where the vat, which was made of stainless steel, had been placed,

Two possible explanations can be imagined, The explosion could have been
caused either by a gas phase detonation, or by detonating composition, In both
cases a chemical reaction involving the consumption of aluminium is likely to
have started the process,

According to the gas hypothesis hydrogen was evolved in accordance with the
reaction

2 Al(s) + 6 H2O(1) - 2 Al(OH)3(s) + 3 H2(g) R,1.

The resulting explosive mixture of hydrogen and air filled the room (the
volume of which was 73 m3) and exploded after having been ignited, for
instance by an electric spark,

However, a stoichiometric calculation shows that the lower
explosion limit (4 % by volume) could not possibly have been reached,
even if all available alurninium had reacted according to Reaction 1.
Another important fact is that no obvious ignition source could be
pointed out. For these reasons the hypothesis of gas phase detonation
was discarded at an early stage.

According to the second hypothesis it was the composition that was
brought to detonation and in the bucket it acted as a bomb. The process
probably started by self-heating, perhaps due to Reaction 1, which is
exothermal enough. After attaining the ignition temperature, ', a combustion
reaction was set off. Finally, the initial low velocity combustion or defla-
gration underwent a transition to high velocity combustion or detonation.

Experimental

The main inorganic components of the present composition,
which turned out to be an explosive with self-igniting properties and
thus very dangerous, were, in decreasing order of quantity, potassium
perch orate, water, aluminium powder, barium nitrate and potassium
nitrate,

The purpose of this anything but comprehensive investigation was to
find out about the conditions precedent for self-ignition. The experiments
therefore include introductory studies on self-heating, ignition, and initiation
of detonation.

Starting from the basic formula (which cannot be given for secrecy
reasons) compositions were prepared with four different aluminium powders
(a survey is given in table 1). Further, one or two chemicals were excluded
or exchanged in some compositions Thus, in one experiment the nitrates
were excluded, in another they were exchanged for the corresponding
chlorides.

The powder designated XP 62000 has been treated with stearine,
Whether this is true for the powders "hell" and "dunker" as well is not
known to us.

Table 1. Data of investigated aluminium powders

Manufacturer Designation Type Particle Size

A - dunkek flake formed 1 - 10 um
B - _ hell " " 50 _ 100 um
C Carlfors Bruk XP 62000 " " 2 - 40 um
D " " A 100 atomized 60 % < 45 um


The aluminium powders have not been analysed chemically.

Self_heating. The self-heating properties of the different compositions were
studied in the experimental arrangement shown in figure 2.

A piece of plastic foam, "Styropor", with the dimensions 13 cm 13 cm x
13 cm was bored so that a cavity with a volume of 5 cm3 remained for the
sample when the Styropor lid was put into place (cf. figure 2). In this way the
sample was surrounded by Styropor walls with a minimum depth Of 4 cm.

An iron_constantan thermocouple, the tip of which was coated with
epoxy resin, was placed in the middle of the sample. The leads, which were
wound with teflon tape, were connected to a potentiometer recorder on which
a continuous temperature-time curve was obtained.

Attempts to measure the pH value of the moist composition with a glass
electrode indicated that the pH of the water phase, if any, was between 6.4
and 6.7.

The initial temperature of the compositions was equal to the
temperature of the room, which varied between 22 C and 26 C

A typical temperature-time curve for self-heating compositions is shown
in figure 3 Substantial self-heating occurs after about 30 hours with a rapid
temperature increase at the end.

The maximum temperature observed was limited to about 130 C. This
limit was set by escaping gases in cases where the lid was blown off, or by
melting of the wall material. Due to -the small amount of sample - ca. 10 g -
the heat evolved by chemical reaction was limited as well

The primary experimental result was that self-heating could occur if, and
only if, the composition contained aluminium powder A (cf. table 1)
Measurements on such compositions further revealed that nitrate and water
had to be present as well Ignition did not occur in any of the experiments

Self-heating was always accompanied by the evolution of ammonia The analysis
was restricted to a qualitative one (Drager tubes were used).

Ignition: Compositions which had been subjected to self_heating appeared dry
and somewhat loose in their consistency. After they had been cooled down to
room temperature, the samples could easily be ignited with a match or by a hot
body. As perceived by eye and ear the combustion was vigorous and subsonic;
we 1herefore prefer to describe it as a deflagration (cf. ref. 2, p. 407, and ref. 3,
p. 1008).

Even samples which had not been subjected to self-heating, but which had
been dried in air at room temperature, burned freely when ignited. This
behavriour was observed in all compositions, irrespective of the type of
aluminium powder used in the preparation.

The ignition temperature of air dried compositions was determined in an
electrically heated oven. Data obtained for standard compositions
containing either A, B or D powder (cf. table 1) are shown in table 2.

.
Table 2 Ignition temperature data for different Al compositions

A1 Amount of Ignition delay in min. at T* in oC
powder comp., mg 260o C 325oC 400oC (estimated)

A 172 2.4
A 178 3.0 250
A 481 no igntion 2.5
B 217 no ignition no ignition 1.2 400
D 371 no ignition 3.1 300
D 288 no ignition no ignition 1.1

The D compositions, i.e., compositions containing atomized aluminium powder,
did not burn as vigorously as did the compositions containing flake formed
powder.

Initiation of detonation So far, none of the samples attained supersonic
combustion velocities, i e., they did not detonate.

In order to establish whether the aluminium compositions were at all prone
to detonate, experiments involving initiation by percussion cups were
performed. These experiments showed that neither self-heated nor air dried
samples weighing 10 g or thereabout could be brought to detonation.

However, when a sample weight of 50 g was used detonation occurred.
This happened when A and B compositions and a composition containing an
atomized aluminium powder designated A 80 (Carlfors Brak) were tested.

Discussion

A complete process including (1) self-heating, (2) deflagration, and (3)
detonation was not observed in any of the crude laboratory experiments
described above. However, each of these three types of reaction could be
brought about separately.

When discussing the growth of explosion in solids, Yoffe summarizes
the different stages which can occur between initiation of reaction and
detonation in the following way (4, p. 254).

(1) Initiation of reaction in the solid by a suitable source of energy, e.g., heat,
light, shock, ionizing radiation, etc.

(2) The growth of reaction from this region of decomposition into an
accelerating burning. This can attain speeds up to several hundred metres
per second.

(3) A sharp transition from burning to low-velocity detonation.

(4) Propagation of low-velocity detonation with a velocity in the region of
1000 m s -1,

(5) Propagation of high-velocity detonation at a velocity of about
5000 m s -1 or higher.

In devising a similar scheme for the purpose of discussing the present
experiments, it should be noted that our observations do not require a
distinction between low- and highvelocity detonation. Thus, we recognize
the following partial processes

(1) Self-heating We assume this process to be due to an
ordinary chemical reaction, i.e., a thermal reaction in the
chemical kinetics sense.

(2) Deflagration, We use this term to designate subsonic
combustion in any system

(3) Detonation In our case only low-velocity detonation caused
by high-velocity (supersonic) combustion is believed to have
occurred

A graphical presentation can be found in figure 4 It is clear that this
picture is essentially a rather crude one, However, we have the feeling that
this diagram summarizes the qualitative behaviour of pyrotechnic
compositions (and maybe other systems in the field of combustion and
explosion as well) in a clear and unifying way. For instance, four of the five
points put down by Yoffe can easily be recognized as follows: "(1)"
corresponds to the transition point B (ignition), "(2)" to B - D - E, "(3)" to the
transition point D, and, finally, "(4)" to D _ E (lIigh-velocity detonation -
Yoffe's point (5) - is probably caused by decomposition reactions and not
necessarily by a combustion process; cf. detonation of azides, for instance.)

In discussing our experimental findings reference will frequently be
made to the temperature-time curve in figure 4.

Self-heating: If metallic aluminium takes part in the self-heating reaction it
is to be expected that the self-heating tendency increases with the specific
surface. The smaller the particles the larger the specific surface and the higher
the reactivity. In addition flake formed particles exhibit a larger specific surface
than do spherical ones of comparable size, It was therefcre not surprising to find
that the small-grained powder desigr~ated A (cf. table 1) was the only one that
turned out to give aluminium compositions capable of self-heating,

The difference in particle size between A and B powders comes out fairly
well from the microscope pictures shown in figures 5 and 6. Still more
impressive are the pictures taken with a scanning electron microscope, figures
7 and 8, Here the three-dimensional appearance of the flakes is clearly to be
seen.

Besides powder Al and water, nitrate turned out to be a necessary ingredient in
self-heating compositions, This observation together with the fact that the
self-heating process was accompanied by the evolution of NH3 suggests that
the following reaction is responsible for the heat generation


8 Al(s) + 3 NO3 - + 18 H2O -> 8 Al(OH)3(s) + 3 OH + 3 NH3(g) R,2.

As pointed out by Ellern (1, p, 302) a nitrate in presence of an active metal
such as aluminium may undergo reduction to ammonia if moisture is present,
Reaction 2 is also discussed by Shidlovsky who writes (5, p, 173): " me
stability of nitrate compositions containing metal powders depends strongly
upon the presence of moisture in the composition and, consequently, upon the
hygroscopicity of the oxidizer. From this we may conclude that with the same
storage conditions, the least significant chemical changes will occur in compo-
sitions containing the least hygroscopic salts - barium nitrates - as an
oxidizer",

Whether Reaction 1 is of importance as well cannot be told from our
experiments since we did not analyse for hydrogen gas.

Our result may be compared with that of Wetterholm (6) who found, in a
study of the reaction between aluminium powders and water, that nitrates in
solution as well as ''highly concentrated and sufficiently diluted" nitric acid
passivates the surface of the aluminium particles. Flake formed powders are
inactivated in the manufacturing process, during which protective agents such
as paraffin, stearic acid, etc are added, In his study Wetterholm found no
correlation between specific surface and reactivity, and points at the difference
in the surface layers as a possible explanation. He found flake formed powders
inactivated by paraffin to be very reactive in contrast to those that had been
treated with stearic acid.

Since the systems studied by Wetterholm and by us are substantially
different one cannot really say that a disagreement exists. However, it is not
easy to find an immediate answer to the question why nitrate ions cause a
protective layer (as they probably do) in one case and consume the aluminium
particles with increasing speed in the other.

The reasons why we failed to achieve temperature values in excess of
130 C have already been given. However, the experimental fact itself is
represented by point A in figure 5.

Ignition. The ignition point is indicated by point B in the diagram. In our
opinion a more rapid reaction with different kinetics starts at this point.

In practice, the intersection between the self-heating curve and the
deflagration curve will surely not be as distinct as indicated in the diagram,
However, if an intersection point obtained by extrapolation of these curves
makes sense in a practical case, the ordinate value of this point might be
used as a well defined ignition temperature.

For self-ignition it is doubtful whether a critical size exists, as probably is the
case for detonation, because the properties of the measuring system may
influence in too high a degree,

Deflagration: After ignition we move from B to D in the diagram, provided
the amount of sample is above the critical size. If not, we stop at some
point C This is what happened to our 10 g samples. All we know about the
critical size at present is that it is to be found somewhere between 10 g
and 5o g.

Contrary to the self-heating process, deflag:ration could be brought about
for all of the powders investigated. We might therefore conclude that the
specific surface of the aluminium powder is of secondary importance as far
as burning is concerned.

Deflagration to detonation transition: In terms of the diagram the use of
percussion cups means that we start the process at D (in the same way as
ignition by external means is equivalent to a start at B) Holzman (2, p 418)
introduces the designation "DDT" - deflagration-to-detonation transition for
this point.

Again, we believe this transition to be due to an abrupt change in the
kinetics of the combustion reaction

Detonation: The fact that detonation could be brought about indicates that
the compositions investigated must be regarded as true explosives We do
not believe that a detonation occurring in a pyrotechnic composition ever
can pass over into the high-velocity detonation region (cf. Yoffe's point (5))
because the required self-decomposition mechanism is not likely to be
found there.

Suggested test procedures

In order to avoid accidents in connection with the handling of aluminium
compositions we recommend that the self-heating tendency should be tested,
e.g., with the aid of a simple apparatus in accordance with figure 2 If a tendency
towards self-heating is observed, it is recommended that a coarser grade of
aluminium powder be employed If this jeopardizes the functioning of the actual
pyrotechnic product it becomes necessary to ascertain the period of time the
composition may be kept in a moist condition.

Summary

Finely divided aluminium powder has been shown to impart
self-heating properties to alurniniurn compositions. Selfheating occurs only if
water and nitrate are present. On standing, such compositions may
self-ignite and detonate after about 30 hours or less.

Only freshly prepared compositions have been studied. However,
attention should be paid to the dried final pyrotechnic product, if stored in a
hot and humid atmosphere.

In discussing our observations an idealized diagram has been used in
order to illustrate the partial processes observed in the laboratory and
characterized as self-heating, deflagration, and detonation as well as the
transitions between these processes. The differences in reaction behaviour
are ascribed to a qualitative difference in the reaction mechanisms (the
details of which are not known).

Acknowledgements

We are grateful to the head of this laboratory, Dr P. Ronstrom, for
permission to publish this work and to Messrs. A Bjork, T Eklund, and K,
Ostman for help with the experiments. Our thanks are also due to Mr.
Michael Callow for linguistical revision of the text.

References


1 Ellern H, Military and Civilian Pyrotechnics, Chem Publ Co, New
York 1968.

2 Holzman R T, Chemical Rockets and Flame and Explosives
Technology, DeRker, New York and London 1969.

3 van Tiggelen A, Balanceanu J C, "Oxydations et combustions", Rev Inst
Franc Petrole, 17:7-8 (1968) 1003-1015.

4 Yoffe A D, "The Growth of Explosion in Solids", Proc Roy Soc A 246
(1958) 254-257.

5 Shidlovsky A A, Fundamentals of Pyrotechnics, Picatinny Arsenal
Dover, New Jersey 1965.

6 Wetterholm A, "Aluminiumpulvers reaktion med vatten (The Reaction
between Aluminium F'owder and Water)", in Reaktionskinetik for
explosivarnnen, Foredrag och diskussionsinlagg 28_29 mars 1957, Svenska
Nationalkommitten for Mekanik, Specialsektionen for Detonik och Forbranning,
Stockholm 1958.



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[*] posted on 14-7-2011 at 18:06


Another ingredient/variable would be stearic acid coating the aluminum, if in some way it got into the game or accelerated an otherwise slower reaction.

"In fireworks, stearic acid is often used to coat metal powders such as aluminium and iron. This prevents oxidation, allowing compositions to be stored for a longer period of time."

http://en.wikipedia.org/wiki/Stearic_acid


[Edited on 15-7-2011 by Morgan]
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[*] posted on 14-7-2011 at 19:05


Quote: Originally posted by Morgan  
Another ingredient/variable would be stearic acid coating the aluminum, if in some way it got into the game or accelerated an otherwise slower reaction.

"In fireworks, stearic acid is often used to coat metal powders such as aluminium and iron. This prevents oxidation, allowing compositions to be stored for a longer period of time."

http://en.wikipedia.org/wiki/Stearic_acid


Don't believe everything you read at Wiki-P.

Extracted from —

Aluminum Powders and Pastes
“The Tale of The Powdered Pig”
Reynolds Metal Company 1960

Stamping: Whereas production of powder by atomizing is a fairly simple process
involving essentially a single operation, producing the flake powder by stamping
requires a number of operations. Particle size in atomizing is controlled by air and metal
temperatures and by spray nozzle adjustment. In stamping, many more factors enter
the picture.

Thickness of original foil material; number, force and rapidity of the individual hammer
blows; number of hammering stages employed; type and amount of lubricant;
arrangement of air agitation and discharge; amount of polishing; etc. — all have an
influence. Also number and selection of screening operations between hammering
stages greatly affect the final product. It is these wide variations in the manufacturing
process that are employed in producing the many types of powder to provide exactly
the characteristics most suitable for each particular application, in the chemical or
explosive field. Reynolds powders stamped from foil are not supplied for pigment
purposes.

Raw material for stamped flake powder is largely in the form of foil from Reynolds foil
plants. The foil must be free from materials such as oil, grease, dirt, iron or other
substances. Also no aluminum alloys can be tolerated because they do not reduce
properly under the hammers, due to their high mechanical properties.

In order to remove the effect of work hardening during rolling and to make the material
as workable as possible, it is first cleaned and annealed; then cut up into particles small
enough to pass through a screen with ¾ -inch openings. Further reduction is by
hammering in stamping mills.

These stamping machines are of several different types. All have multiple hammers
raised by cams and allowed to fall to strike the steel anvil by force of gravity. Anvil and
lower end of hammers are enclosed to confine the powder. Additional material is fed
into the mill at frequent intervals while discharge is continuous. Material at this stage will
pass through a screen with 20 openings to the inch (20-mesh screen).

Lubricant is necessary to prevent the small particles from welding together under the
impacts from the hammers. Lubrication also facilitates spreading of the metal under
impact, thus increasing the rate at which large flakes are broken up into small flakes.
Stearic acid is commonly used, although tallow, olive oil, rape oil or other oils may be
employed.


Action of the hammers in beating out the metal into thinner and thinner flakes work
hardens or embrittles the material and so assists breakup. At the same time,
hammering one flake over the edge of another produces a shearing action that further
aids reduction of particle size.

Mills in the third stage usually employ more hammers, operate faster, produce a
greater number of lighter blows than the second group of machines. All mills are in
banks as shown in accompanying illustrations. These, like the other mills, are charged
at regular intervals (such as 1-hour) with the air discharge being continuous. Fourth and
fifth stages may be utilized for certain types of product, although particles from this third
stage will pass through 40 to 300-mesh screens, depending upon length of time in the
mill.

As will he further explained under characteristics, page 62, and under testing, page 66,
any particular powder rarely has all particles of the same size, unless specially made.
Most powders contain a certain amount of fines of a certain size range, with some
larger particles.

&c., &c., &c.


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[*] posted on 15-7-2011 at 02:12


3 MICRON COATED ALUMINUM FLAKE
http://www.northstarpyro.com/PYROTECHNIC_ALUMINUMS-ECKART_54...
http://www.highqualitychems.com/servlet/the-ALUMINUM-ECKART-...
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[*] posted on 15-7-2011 at 03:14


Quote: Originally posted by prometheus1970  
I was making a batch of black powder. Rather than ball milling it, I make a soln. with the proper amount of KNO3, then soak my charcoal powder with that then let it dry. This time I added some Eckhart 5413 to the mix to make it sparkly. After awhile I noticed a rather strong ammonia smell emanating from the batch. I could even see vapors rising from the mush. I cannot think of any way I could get either NH3 or NH4OH from a mixture of charcoal, KNO3, H2O: and Al powder. The KNO3 has been kept in an airtight container and is about 5 years old. The mixture is in a sauce pot (most likely aluminum, with spots of teflon coating missing). Any ideas what is happening?



Don't use water with mixtures that contain aluminum powder and nitrates. They could self-ignite.
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[*] posted on 15-7-2011 at 07:07


The charcoal I made is from paper napkins. I use this because it has a much lower density, is therefore more absorbent and doesn't require as much mechanical action to make it a fine powder. I guess I should hold off on adding the Al until the mix is dry, then mix it in as well as I can?



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[*] posted on 15-7-2011 at 09:46


Quote: Originally posted by Blasty  

Don't use water with mixtures that contain aluminum powder and nitrates. They could self-ignite.


A little boric acid works wonders.

deathmix by Fiore DiSaster
American Fireworks News #29 February, 1984
Posted with the permission of the publisher.


wherein the gentleman resorts to an Alias, that he may Spout his hillbilly
opinions clearly labelled (sic) as such, without the Constraints of Scientific
Method.

The bright idea frequently occurs to pyrotechnists to "improve" so called
electric green star formulations made with barium nitrate, a chlorine donor
and a metal fuel, by adding a quantity of chlorate to the mixture.

Another version of this mistake is adding barium nitrate to an otherwise
chlorate-based electric green, thinking that by doing this, the sensitivity of
the mixture may be reduced.

Both practices are mistakes and may qualify for the Deathmix Award.

The reason is this: whan (sic) a chlorate, a nitrate and a metal fuel such
as magnalium or aluminum are dampened with water and allowed to
stand for a time, there is a high probability that ammonium chlorate may
form. Basically, it is just a matter of time and temperature.

In Fireworks Principle & Practice, Dr. Shimizu clearly lists ammonia as a
reaction product of nitrates, water and aluminum allowed to stand
unbuffered for a period of time.

The logic behind adding barium nitrate to a chlorate electric green is a
mistaken application of a practice that may be sound when applied to
resin fuel systems. Since the sensitivity of the mixture increases as the
chlorate oxidizer content increases, the reasoning goes, reducing it by
using some barium nitrate instead will thereby make a safer mixture. But
this runs afoul of chemistry.

The mention of ammomium chlorate will cause veteran fireworkers to
blanch. For those who are still sorting out the list of demons one may
encounter when making fireworks, ammonium chlorate is a highly
unstable compound which tends to have a short life, eventually flying
apart in a detonation. Having this form in a damp star mixture is the rough
equivalent to adding blasting caps to the mixture. If it DOES go, the fact
that the mixture is damp is no guarantee of safety: look at
nitrate-aluminum blasting slurries; the water actually makes them more
powerful!

Traditional "electric" green is usually taken to mean a mixture with 60-70%
barium chlorate, 15-20% aluminum and some resin fuel, along with a
binder. Blasting slurries also contain about the same amount of aluminum.
Now, this mixture is touchy enough to start with traditional wisdom is that
one must get stars made with it dried in a hurry, and in the shade but if a
nitrate is added, it becomes even more treacherous because the addition
of nitrogenous material sets up the conditions for ammonium compound
formation. Then one is really walking on eggs. Let the mixture sit around
damp for long enough at the right temperature and the chances are very
good that one will have a true Deathmix.

In a barium nitrate green with metal fuel and, say, Parlon as the chlorine
donor, boric acid may be used to counteract the nitrate's reaction with the
metal fuel, which is an alkaline.reaction. But add a chlorate to the brew
and you're going to lose either-way, if it goes-alkaline, the ammonium
chlorate wil.1 get you; if it goes acidic from the buffer, you will have the
chlorate acid problem. An arpphoteric buffer won't know whether to go left
or right.

All of this trouble arising from the chlorate would be one thing if there were
no other way -to get a good electric green. But it just isn't necessary. Not
only are barium nitrate-based electric greens safer to handle than chlorate
versions, but they are far cheaper to make. This may not be obvious to
the small scale pyrotechnist who pays hobby/retail prices for his
chemicals, due to the seller's having to repackage and ship them to the
tune of a considerable time investment . But at the commercial level, one
can make the whole barium nitrate electric green mixture for about the
same price as the oxidizer alone costs in a barium chlorate mixture. Or
close enough to this to make the chlorate version "premium priced".

Barium nitrate greens using aluminum or magnalium can be water bound,
provided that they are buffered with at least one percent boric acid; it
seems to be best to dissolve the boric acid in the water/alcohol, which will
be used to dampen the mixture, before adding it to the dry composition.
This way, the acid is immediately dispersed through out the mixture and
immediately on the job. If it is added dry, it never gets this well dispersed.
Barium nitrate electric stars should also be dried out as quickly as
possible, since it is possible, over enough time, for the limits of the
buffering to he reached. If this occurs and the alkaline reaction begins to
take place, the stars can heat up. However, in this writer's experience, no
reactions have been noticed within about four days, when the boric
acid was predissolved.

One problem that I sometimes arises with water bound barium nitrate
greens is that if the star composition is over-dampened, some barium
nitrate can leach into the blackpowder prime. If this happens to a sufficient
extent, the prime becomes a "smolder" mix, and the stars may take up to
three seconds to ignite after leaving the shell. This can actually be used
deliberately to give an effect which seems much like color changing stars,
when mixed with another star which ignites immediately. In any case, for
rapid ignition, it is best not to over-dampen the star composition and to
use as much alcohol as one can without inhibiting the binding ability of the
dextrine.

One further note: Deathmixes are not limited to greens. Another
potentially nasty one is yellow made with potassium chlorate, barium
nitrate and aluminum. Different color, same danger...,DON'T.


-----------
From American Fireworks News #34 July 1984
Tell The WiZ [donald j haarmann]


"Fiore DiSaster" has chosen to call mixtures containing nitrates, chlorates
and aluminum "deathmix" (AFN #29, Feb. 84). I, for one, do not agree with all
that the writer has to say on this subject, although the ignition source sited
at some recent incidents has been green stars that ignited during drying,
and as little in the way of aesthetic value would be lost by avoiding the use
of these mixtures, it would be better to err on the side of caution and avoid
them.

This combination does not seem to be common, as a check of the WiZ s
data base (1250 formulas) reveals that there have been published only five
formulas that contain at the same time a nitrate (barium), a chlorate (pot-
assium or barium) and aluminum. I found one each in Lancaster, Davis,
Weingart and two from Degn. None mention the use of a buffer such as
boric acid or a chlorine donor.

In the data base I found no formula that contains at the same time:

barium nitrate
potassium chlorate
magnesium

barium nitrate
barium chlorate
aluminum

potassium nitrate
potassium chlorate
aluminum or magnesium

potassium nitrate
barium chlorate.


Despite Dr. Shimizu s observation that strontium nitrate is even more
reactive with aluminum than barium nitrate, I found three formulas in the
data base for red compositions that contain all three ingredients, the nitrate
being strontium.

The reason that these combinations are not used may be lack of results
rather than safety.


djh
---
That woman, as nature has created her,
and man at present is educating her, is man's
enemy. She can only be his slave or his despot,
but never his companion. This she can become
only when she has the same rights as he and
is his equal in education and work.

Leopold von Sacher-Masoch
Venus in Furs
1870

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vulture
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[*] posted on 16-7-2011 at 03:04


Quote:

Don't use water with mixtures that contain aluminum powder and nitrates. They could self-ignite.


Not only aluminium. I once had a scary experience with a nitrate mixture that contained fine Zinc powder. Just high humidity caused it to heat up considerably.




One shouldn't accept or resort to the mutilation of science to appease the mentally impaired.
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AndersHoveland
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[*] posted on 16-7-2011 at 12:56


Interestingly, perchlorates will not be so easily reduced. Perhaps you could substitute KClO4 for the KNO3 in your black powder if you desire to add aluminum powder.
When making compositions, one should always consider chemical compatibilities. Any time sulfur is added to a composition, some of the sulfur will inevitably oxidize in storage, making the mixture somewhat acidic. In pyrotechnics for this reason a small quantity of sodium bicarbonate is often added to compositions that contain sulfur. This is why chlorates are incompatible with sulfur, as there could be spontaneous ignition in storage. Unfortuneately there are no simple rules that cover all situations. For example, anything organic is incompatible with hydrogen peroxide (unless it is mixed immediately before use), whereas aluminum powder is compatible mixed with hydrogen peroxide. But in compositions containing sulfur and nitrates, it is just the reverse.




I'm not saying let's go kill all the stupid people...I'm just saying lets remove all the warning labels and let the problem sort itself out.
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prometheus1970
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[*] posted on 16-7-2011 at 20:29


The charcoal I use is so "fluffy" and easy to pulverize that I could use the KNO3 soln. to make it (the BP), then dry it out and add the Al powder after it's dry and mortar and pestle it into a homogeneous mixture. My first thought would be to grind it together, but the KNo3 with Al would be, I'm afraid, too "ready to go off" for a process as violent as grinding. I also would like to add sulfur to this mix, but that's a crude flash powder there which would be okay for use, but would make grinding (in a coffee grinder) too risky



Just because you're paranoid doesn't mean everybody isn't out to get you.
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prometheus1970
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[*] posted on 17-7-2011 at 07:49


I'm guessing that the reduction reaction that occured with the water, KNO3 and Al effectively "removed" all the KNO3 from my batch because now, though dry, it will not ignite!



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[*] posted on 17-7-2011 at 08:12


Quote: Originally posted by vulture  

Not only aluminium. I once had a scary experience with a nitrate mixture that contained fine Zinc powder. Just high humidity caused it to heat up considerably.


You could add a little potassium dichromate to protect the zink.
If'n you do please report back with your results.

Though dichromate(s) is not found in nitrate electric star comps,
it is found in those using K chlorate where its use may be that of a catalyst.

[Edited on 17-7-2011 by The WiZard is In]

[Edited on 17-7-2011 by The WiZard is In]
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