For example a formula containing sulfur can be used safely with potassium Perchlorate(KCLO4) but under no circumstances should it be used with potassium chlorate(KCLO3), although the chemical formula looks very similar, mixing a chlorate and sulfur is considered very risky and has caused many deaths. Sulfur and chlorate combinations are rarely used in modern fireworks making.
Other chemical reactions that can also cause spontaneous ignition:
Aluminum and nitrates: This can produce an exothermic reaction (similar to oily rags in a bucket) creating enough heat to cause ignition of the device, a smell of ammonia is an indication of this reaction an time to dispose of it. Boric acid is added to mixes containing both nitrates and aluminum.
Chemicals can fall under many categories some of which are, oxidizers, organic and metallic fuels and color enhancers.
Barium Nitrate(BaNO3):Green color producer, used mostly in flares and some flash powders, this oxidizer is poisonous.
Strontium nitrate:(SrNo3):Red color producer, used mostly in flares, stars and Bengal's
Potassium Perchlorate(KCLO4):Used in most modern fireworks, it is used in compositions such as whistle mix, flash powder and most colored stars. Its sensitivity is higher than Nitrates but lower than Chlorates, for the exception of flash powder and whistle mix, is quite safe to handle for most beginners. Potassium Perchlorate replaced potassium chlorate in many older formula because of its higher stability.
Potassium Chlorate(KLO3):Very sensitive oxidizer, it is rarely used in modern pyrotechnics with a few exceptions which are electric spreader stars, and when brighter colors are required. Reacts with sulfur, ammonia, copper and their salts.Chlorate should only be used when you have a good understanding and experience with Perchlorate based formulae.
Potassium Dichromate:(K2Cr2O7)Oxidizers. Used mostly as a surface treatment to suppress the corrosion and reactivity of magnesium. This chemical is severely poisonous(cancer causing)and very corrosive. Also used in electric spreader stars.
Ammonium Perchlorate:(NH4CLO4)Slow burning oxidizer used in flares, strobe stars and composite rocket propellant.
Lead tetraOxide(Pb3O4):Highly toxic substance, used for making crackling microstars(dragons eggs)
Bismuth trioxide:Non toxic alternative to lead tetraOxide.
Barium Carbonate:(BaCO3)Green color producer also used as an acid neutralizer in compositions containing potassium Chlorate. Poisonous.
strontium carbonate(SrCO3)Most common red collorising agent.Slightly hygroscopic.
Calcium carbonate(CaCO3):reddish orange color producer, can be used as a substitute for strontium carbonate and is not hygroskopic.
Copper Carbonate(CuCO3):Used as a blue color agent, cannot be used with chlorates.
Copper2Oxide(CuO):Common blue colorising agent, cannot be used with chlorates.
Sodium Oxalate:(Na2C2O4) Hygroskopic powder used as a yellow coloring agent and also used as a delay agent in glitter formulations.
Dextrin: Most common binder whose solvent is water. Can be made by baking corn starch until light brown. Used in small amount because it can cause poor colors.
Parlon, PVC, Saran: solvent is acetone and laquar thinner
Red gum, shellac: Solvent is ethyl alcohol.
Nitrocellulose laquar: Used mainly for compositions that cannot use water as a solvent as in dragons eggs. It is made by dissolving 10% by weight in grams of smokeless powder to 90% by volume in ml of acetone.
Potassium Benzoate: Fuel used for making whistling mix(organic flash powder) once combined with potassium Perchlorate makes a sensitive mixture, which should only be attempted when sufficient level of experience is achieved. whistle mix is never rammed, but rather is pressed because of its sensitivity.
Red gum: Fuel used in many star compositions, also used as a binder whose solvent is alcohol.
Shellac: Considered a superior fuel in most colored compositions, also a binder whose solvent is acetone and alcohol.
Aluminum(Al): By far the most widely used metal in pyrotechnics and is often used to produce a glitter effect but in its dark form is used to produce powerful flash powder. When ever aluminum is used with a nitrate based oxidizer a few percent of boric acid is added to prevent the aluminum from being oxidized by an alkaline reaction. This reaction causes heat which could cause a fire.
Several forms of aluminum are used in pyro:
Dark aluminum: Used mostly for flash powder but also used in some star formulations. Made by an expensive process where a sheet of aluminum is bonded between two sheets of paper then heated and milled.
Aluminum, spherical 80 - 325 mesh: Used in glitter formulations, produces white branching sparks, duration of the sparks depends on the coarseness of the material.
Aluminum, firefly:10 -12 mesh: Produces long hang time in certain star formulations, also great in hot burning fountains.
Titanium 40 -100 mesh: Produces bright white streaming sparks in fountains and bright tails in comets. Available in spherical, and sponge, by far the spherical is the safer to use in compositions because spheres of titanium are less likely to spark.
iron (Fe): produces bright orange sparks, must be coated with linseed oil if finished products are stored for more than a week.
Antimony trisulphide(Sb2S3):Use in some glitter formulas, also used in white star formulas.
Magnesium(Mg): A highly reactive, flammable metal used to brighten flames without decreasing color. Most of the time it requires a protective coating such as potassium dichromate.. Reactive with water, other solvents must be used to avoid this.
Zinc (Zn): metal Used as a fuel in zinc spreader stars and used as a fuel in rockets in some old time formulas using sulfur as an oxidizer.