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Pyrotechnic Chemical Incompatibilities

Some combinations of chemicals lead to especially sensitive or instable mixtures. There are many more of such incompatible chemicals/mixtures than listed here but these are some of the more commonly encountered types:

1. Chlorates and sulfur. Mixtures containing both are not only very sensitive to friction and shock but are also known to ignite spontaneously. The sulfur reacts with water and air to form trace amounts of sulfuric acid. This will react with chlorates to form chlorine dioxide, a yellow explosive gas that will ignite most flammable materials upon contact. Addition of small amounts of barium or strontium carbonate to chlorate based compositions is sometimes done to prevent buildup of acid, even in compositions without sulfur. Many older texts on pyrotechnics describe the use of chlorate/sulfur based compositions. Today, many alternative and much safer compositions are available and there is therefore no excuse for the use of chlorate/sulfur mixtures. This also means chlorate based compositions cannot be used in items that also contain sulfur based mixtures. For example: chlorate based stars cannot be primed with black powder. Nor can a H3 burst charge be used with black powder primed stars (or stars containing sulfur).
2. Chlorates and ammonium compounds. Mixing these will allow ammonium chlorate to form in a double decomposition reaction that takes place in solution (moisture speeds up the process). Ammonium chlorate is a highly instable explosive compound. It decomposes over time producing chlorine dioxide gas (see chlorates and sulfur). Mixtures are likely to spontaneously ignite upon storage or may explode for no apparent reason. An exception seems to be the use of ammonium chloride and potassium chlorate in some smoke compositions. According to Shimizu this combination is safe due to the lower solubility of potassium chlorate (compared to ammonium perchlorate). I personally would still use these mixtures with great caution (or avoid them) since it seems inevitable that small amounts of ammonium chlorate will still form. The lower solubility of potassium chlorate will make it the -main- product in a double decomposition reaction but not the -only- product.
3. Chlorates with metals and nitrates. These mixtures show the same problems as chlorate/ammonium compound mixtures. The reason is that nitrates can be reduced by most metals used in pyrotechnics to ammonium. The reaction rate of this reaction is increased by presence of water. Over time (for example when drying) these mixtures may spontaneously ignite or become extremely sensitive. The fact that ammonium forms in a relatively slow reaction is treacherous. These mixtures are referred to as 'death mixes' by some.
4. Aluminum and nitrates. Mixtures of these compounds sometimes spontaneously ignite, especially when moist. The mechanism is assumed to be as follows: the aluminum reduces some of the nitrate to ammonium, simultaneously forming hydroxyl ions. The aluminum then reacts with the alkaline products in a very exothermic reaction leading to spontaneous heating up of the mixture. This can eventually lead to ignition. The reactions take place in solution and therefore moisture speeds up the reaction. The process is usually accompanied by the smell of ammonia. Some types of aluminum are more problematic than others. Stearin coated aluminum is generally safer to use. The whole process can be prevented in many cases by the addition of 1 to 2 percent of boric acid. This will neutralize the alkaline products. It is best to bind such compositions with non-aquaous binder/solvent systems such as red gum/ethanol. Since aluminum/nitrate mixtures are extensively used it is important to be aware of this problem which is why the combination is listed here.

General Solubility Information
The following is a listing of available materials that are (among other things) used as a binder in pyrotechnic type formulations. Those so marked with " * " preceding the item indicate that the material so used in solution, that is to say, it is dissolved in the appropriate solvent before mixing into the formulae. It should be noted that all of these materials may be used in solution but those so noted must be dissolved first because of their more difficult to solvise properties. Do not allow complete solvation before evaporation and drying the mixture resulting in adhesive bond failure. Some of these materials may take as long as 24 hours at room temperature to completely dissolve.
If maximum strength is required, binder solutions should be used instead of moistening the dry mixture containing the binder. A solution allows a more thorough, homogenous mixing with adequate wet-out and a cured strength many times greater than the same binder when used dry.
Those so indicated with "+" also have good moistureproofing properties (some better than others) because they are impervious to moisture themselves and seal the ingredients in the formula that are hygroscopic from the air and moisture they may otherwise absorb from it.

	Virgin Kraft Paper Sheets and Rolls					Super Strips		Secret Weapon Strips
	35# Blonde	50# Blonde	40# Brown	55# Brown	70# Brown	70#, 1"	70#, 2"	60#, 1"	60#, 2"
Pupadel Cans
Siatine Cans
3" - 4" Can, Inner
5" - 6" Can, Inner
7" - 8" Can, Inner
10" - 12" Can, Inner
Pupadel Pasting
Siatine Pasting
3" - 4" Can, Pasting
5" - 6" Can, Pasting
7" - 8" Can, Pasting
10" - 12" Can, Pasting
Small Crossettes
Large Crossettes
Match Piping, Nosing
Small Can, Outer Dry Wrap
Large Can, Outer Dry Wrap
3", 4", & 5" Ball
6", 7", & 8" Ball
10", & 12" Ball
16", & 24" Ball