Chlorate and Perchlorate Explosives
by Dennis Fritsinger
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revised 7/29/89
*** WARNING ***
The following material is presented here in the interest of
technical enlightenment only. This information, at the time of its
writing, is as accurate as the author has knowledge of. This
material is the result of years of experience and many hours of
careful experimenting. The manufacture, transportation and detona-
tion of explosives may be in violation of state, federal or local
laws. The preparation and handling of potentially unstable explo-
sive compounds is by its nature a DANGEROUS ACTIVITY and mishaps
could result in injury or death.
The bottom line is: Always exercise CAUTION when preparing or
utilizing these explosive compositions.
FLASH COMPOSITIONS
The chlorate/perchlorate flashpowder described here, if
prepared and manipulated with moderate caution, is one of the
safest explosives I've dealt with and my preferred choice for a
variety of applications requiring a flammable powder explosive,
such as salutes, aerial displays requiring a loud report, etc. This
explosive can be quite effective when detonated in moderate to
large quantities and can be initiated directly by ignition. Its
brisance is much greater than conventional blackpowder-type explo-
sives when confined.
A) OXIDIZERS
Of the chlorates/perchlorates that I've used, the most stable
is the perchlorate group. The most active, but harder to get, is
ammonium perchlorate. The least active seems to be sodium perchlor-
ate. Potassium perchlorate is by far the most commonly available,
although on a couple occasions my supplier has substituted chlorate
much to my chagrin, and performs just as well as its chlorate
relative. The perchlorates are intrinsically more stable and less
reactive. In general, perchlorates are much safer in contact with
combustible substances and are relatively safe to use with sul-
fur/sulfide compounds. The problem with chlorates and sulfur
compounds comes from the fact that sulfur/sulfides can react with
chlorates and form chloric acid, which is a rather unstable explo-
sive.
B) FLAMMABLE SOLIDS
One of the most important components of flashpowder is fuel
for the reaction. It is important that this fuel burn rapidly, as
the explosive force is derived from the rapid expansion of gasses
from this oxidizing/burning fuel when confined. The best fuels
suited for this purpose are light combustible metals and the two
best metals I've used are magnesium and aluminum. Finely divided
magnesium of 100 mesh or finer is the fastest burning but is more
expensive. Pyro or German black grades of 400 mesh or so is almost
as fast and at about a third the price per pound.
C) COMPOSITION PREPARATION
The beauty of the basic chlorate/perchlorate flashpowder is
its simplicity. There are only two components to blend together,
which is a relatively safe procedure providing care is taken to
eliminate anything that can produce a spark. Using plastic or glass
containers and utensils is recommended. Try to avoid any kind of
scraping or fricative activities when mixing or manipulating
ingredients. Also very important tips to keep in mind are to
prepare flashpowder FAR AWAY from ANY flame or heat source and to
take steps to eliminate DUST ACCUMULATION period. Excessive dust
buildup is probably the major cause of sudden explosions in both
commercial and clandestine firework factories. A slightly humid
atmosphere is ideal for reducing combustible dust in the air making
preparing pyrotechnics safer. I found that a small room humidifier
to be very effective for this purpose.
The chlorates/perchlorates are hydroscopic by nature and are
usually rather chunky and need to be reduced with a mortar/pestle.
I found that AFTER grinding up the chunks that adding a small
amount of the aluminum and mixing it in will keep the chlorate from
clumping and retain a flour-like consistency, which is ideal.
I found through experimentation that a ratio of 7 to 3 (seven
parts oxidizer to three parts fuel) works most efficiently. Keep in
mind that when measuring solid chemicals, the proportions are by
WEIGHT, not volume. Get a good lab scale. Using a measuring cup
won't get the job done!
Most commercial pyrotechnics using chlorate flashpowder use
the basic aluminum chlorate combination and it works well, but
improvements can be made by the addition of compounds that will
change the oxidation or burning rate of the composition.
Replacing one of the three parts of aluminum with magnesium
gives both a brighter flash and a louder report. Also, the addition
of a small amount of antimony sulfide, (but no more than 10 per-
cent; e.g., with 70 grams of chlorate, use no more than 7 grams of
antimony sulfide) will speed the reaction by an order of magnitude.
But be VERY CAREFUL because the more antimony sulfide added, the
MORE UNSTABLE the composition becomes. Use too much and the compo-
sition can explode without any initiation. Adding finely powdered
polyvinyl chloride or cellulose based plastic will add smoke to the
explosion but slows the burning rate. This can be useful for a
variety of applications requiring smoke with detonation such as
signaling, special effects, etc.
My general rules when preparing this and the following compo-
sitions are to make only small amounts at a time and never keep
more than a very small amount on hand. My reasoning is to reduce
the chance of an accidental ignition causing a chain reaction type
of explosion. The accidental detonation of large amounts of these
flash compositions can reduce the average suburban house to splin-
ters in a matter of seconds. Minimizing friction, heat or static
electricity is imperative!
OTHER FLASH COMPOSITIONS
Here are some alternative formulas that work equally well, but
employ some different combinations of fuel/oxidizers. They all
share similarities in velocity of detonation, burning rate (bris-
ance), sensitivity, etc. Again, proportions are by weight.
COMPOSITION #2
1 to 3 parts --- POTASSIUM PERCHLORATE<br>
1 part --------- SODIUM SALICYLATE, USP, fine powder
COMPOSITION #3
3 parts -------- POTASSIUM PERCHLORATE<br>
1 part --------- ANTIMONY TRISULFIDE<br>
1 part --------- LAMPBLACK<br>
1 part --------- ALUMINUM, DARK PYRO, 400 mesh<br>
1/10 part ------ BARIUM CARBONATE
COMPOSITION #4
3 parts -------- POTASSIUM PERCHLORATE<br>
3 parts -------- BARIUM NITRATE<br>
4 parts -------- ALUMINUM, DARK PYRO, 400 mesh
COMPOSITION #5
60 parts ------- POTASSIUM CHLORATE<br>
23 parts ------- WASHED (NOT FLOWERS) SULFUR<br>
5 parts ------- ANTIMONY SULFIDE<br>
12 parts ------- POTASSIUM NITRATE
COMPOSITION #6
6 parts -------- POTASSIUM CHLORATE<br>
3 parts -------- WASHED (NOT FLOWERS) SULFUR<br>
1 part --------- POWDERED CHARCOAL or SUGAR (my idea)
COMPOSITION #7
6 parts -------- POTASSIUM CHLORATE<br>
2 parts -------- WASHED (NOT FLOWERS) SULFUR<br>
1 part --------- METALLIC ANTIMONY, FINELY POWDERED
NOTE: Compositions 5, 6, & 7 use potassium chlorate in
combination with sulfur. These formulas came from an
old textbook and are a bit trickier to work with.
Use washed or lab grade sulfur, NOT FLOWERS OF
SULFUR. Flowers of sulfur is too acidic and extreme-
ly dangerous to combine with chlorates. Remember
about chloric acid? Blend powders carefully and use
immediately. It is probably not a good idea to store
these for any length of time.
HIGH EXPLOSIVES USING CHLORATES/PERCHLORATES
An improvised "plastic explosive" can be made from potassium
chlorate and, of all things, petroleum jelly. This requires that 90
parts of finely powdered potassium chlorate are blended with 3
parts Vaseline or other petroleum jelly and then mixed with 7 parts
of semi-melted paraffin. I found this stuff to be insensitive to
heat or shock. If ignited, it burns with a yellowish flame. Howev-
er, this mixture is quite effective when initiated with a number 6
or 8 blasting cap. When blasting caps are not available, the
mixture will detonate when initiated with a moderate amount of
picric acid or mercury fulminate primer exploded by ignition or
concussive means. Lead azide or lead picrate can also be used but,
in my opinion, they are too damn sensitive. Using this mixture,
when confined to a medium density, the velocity of detonation can
be expected to fall between 2,925 and 3,180 feet per second, which,
in my opinion, classifies it as a high explosive suitable for
demolition work. It is a good idea to store it in a airtight/water-
proof container.
Here are other mixtures which exhibit similar characteristics.
These compositions were successfully initiated using a picric acid
detonator electrically fired and using a 10 inch long, 1 inch
diameter copper tube for confinement.
COMPOSITION #1A
90 parts ------- POTASSIUM CHLORATE<br>
3 parts ------- HEAVY PETROLEUM OIL (#2 DIESEL)<br>
7 parts ------- PARAFFIN
Packing Density = light to medium<br>
Velocity of Detonation is approximately 2,150 and 2,750 FPS
COMPOSITION #2A
89 parts ------- SODIUM CHLORATE<br>
11 parts ------- PARAFFIN
Packing Density = light to medium<br>
Velocity of Detonation is approximately 2,480 to over 2,600 FPS
COMPOSITION #3A
90 parts ------- POTASSIUM CHLORATE<br>
10 parts ------- PARAFFIN
Packing Density = light to heavy
Velocity of Detonation is approximately 2,137 to over 3,560 FPS
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