The mixture, that is inherently dangerous, due to it's high sensitivity or instability, is called a Deathmix. One should realize, which chemicals are compatible with each other, before mixing anything. Even certain combinations in some known, especially older formulas, may be defined as death mixes.
Important! The scratches of plastic hardware, especially ball milling jars, will store traces of chemicals. This applies also to the ball milling media. You must have enough application-specific hardware to make sure, that even traces of incompatible chemicals may not interact.
Disclaimer: Following information does not imply any mixture as "safe".
- Potassium permanganate with any fuel
Potassium permanganate is exceedingly dangerous if mixed with any fuel. Prevention: DO NOT PURCHASE POTASSIUM PERMANGANATE.
- Red phosphorus with any oxidizer
Red phosphorus is exceedingly dangerous mixed with any oxidizer. Prevention: DO NOT PURCHASE RED PHOSPHORUS.
- Chlorates with ammonium salts
Ammonium of ammonium chloride, will react with alkali metal chlorate forming ammonium chlorate and alkali metal chloride. Ammonium chlorate can DETONATE of minimum friction, or even of no reason at all. Ammonium for the reaction may also be generated at the reduction of nitrates, please see below. Some known formulas exhibit both nitrate and a chlorate, so avoid them! Prevention: NEVER MIX AMMONIUM SALTS OR ANY NITRATES, WITH CHLORATES.
- Chlorates with sulfur
Finely powdered sulfur will react with the oxygen of the air, forming sulfur dioxide. Sulfur dioxide reacts further with moisture to form sulphurous acid, which eventually reacts with chlorate forming chloric acid. Chloric acid makes mixture unstable, and is even capable of igniting sulfur at room temperature. Prevention: NEVER MIX CHLORATE WITH SULFUR.
- Chlorates with sulfides (arsenic, antimony, other)
All mixtures containing chlorates with sulfides, are highly sensitive to the heat, shock and friction. There are much safer and less toxic fuels available. Prevention: NEVER MIX CHLORATES WITH SULFIDES.
- Chlorates with metal powders
All mixtures containing chlorates with metal powders, are sensitive to the heat, shock and friction. There are always safer perchlorate versions available for these mixtures. Prevention: NEVER MIX CHLORATES WITH METAL POWDERS.
- Flitter aluminum with alkaline nitrate and water
In alkaline aqueous conditions, aluminum powder reacts with water forming hydrogen. Hydrogen, in its free-radical form, is capable of reducing metal nitrate to the corresponding amide. The amide will react further with moisture, to form ammonia and metal hydroxide, thus making the mixture even more basic. In the reaction, much heat is generated. Prevention: USE AS LITTLE AS WATER IN ETHANOL AS NECESSARY, WET COMP ONLY AS NECESSARY. USE SMALL PERCENTAGE OF BORIC ACID.
- Magnalium or fine aluminum with nitrates
All mixtures containing nitrates with these metals, are more sensitive to the heat, shock and friction than their safer perchlorate versions. Also, there is a risk of nitrate reducing reaction as above. Prevention: AVOID MIXING NITRATES WITH THESE METALS. USE SMALL PERCENTAGE OF POTASSIUM DICHROMATE WITH MAGNALIUM. WITH ALUMINUM, USE SMALL PERCENTAGE OF BORIC ACID. DO NOT STORE FOR A LONG PERIOD OF TIME.
- Magnesium with water
Magnesium reacts with water or with moisture, forming magnesium hydroxide, hydrogen gas and heat. Prevention: NEVER MIX WATER WITH MAGNESIUM. ALWAYS COAT MAGNESIUM WITH POTASSIUM DICHROMATE OR LINSEED OIL.
- Magnalium or fine aluminum with water
Magnesium in magnalium, reacts with water forming magnesium hydroxide, hydrogen gas and heat. Magnalium is somewhat less reactive than magnesium alone. This applies also to aluminum, when it's particle size is small. The danger is cumulative with nitrates, see above. Prevention: AVOID MIXING WATER WITH THESE METALS. USE SMALL PERCENTAGE OF POTASSIUM DICHROMATE WITH MAGNALIUM. WITH ALUMINUM, USE SMALL PERCENTAGE OF BORIC ACID.
- Unprotected magnesium, magnalium with ammonium perchlorate
Moisture will react with magnesium forming magnesium hydroxide. Magnesium hydroxide will react further with ammonium perchlorate, forming ammonia and magnesium perchlorate. Magnesium perchlorate is hygroscopic, and will draw more moisture from air. The reaction of anhydrous magnesium perchlorate with moisture generates heat. Linseed oil does not protect magnesium/magnalium from ammonium perchlorate! Prevention:ALWAYS COAT MAGNESIUM/MAGNALIUM WITH POTASSIUM DICHROMATE. POWDERED DICHROMATE ADDED TO THE COMPOSITION WILL NOT PREVENT THE REACTION.
- Copper or zinc with ammonium perchlorate
Copper or zinc reacts with AP as magnesium/magnalium, but to lesser extent. Some strobe compositions exhibit this combination. (Potassium dichromate uncertain->see discussion). Prevention: CHECK pH FOR NEUTRAL. NEVER USE WATER BINDER. USE IMMEDIATELY AFTER MIXING.
- Magnesium, magnalium with boric acid
Boric acid passivates aluminum, but attacks magnesium and magnalium. So to say, magnesium and magnalium can not be stabilized by acid buffer. Prevention: NEVER MIX BORIC ACID WITH MAGNESIUM OR MAGNALIUM.
- Nitrates with ammonium perchlorate
Alkali nitrates react with ammonium perchlorate forming ammonium nitrate and alkali perchlorate. Ammonium nitrate is hygroscopic, and will draw moisture from the air. With metal, it will pose dangers as discussed above, and will at least lead into ignition problems. For example a piece of visco in ammonium perchlorate comp may result into a dud or a low-break, due to the wetting. Prevention: NEVER MIX NITRATES WITH AMMONIUM PERCHLORATE. NEVER USE VISCO AT INTIMATE CONTACT WITH AP COMPOSITIONS.
- Unprotected iron powder with water
Water and iron will form 'rust', which will eventually render the composition useless. The comp may well become a Deathmix, since the reaction evolves heat; disposable hand warmer packs generates heat with iron powder, water, catalyst and atmospheric oxygen. The burning speed of 'rusted stars' may slow down, and glowing dross may fall to the ground and audience. Prevention: COAT IRON POWDER WITH LINSEED OIL, WD40 OR STEARIN. USE AS LITTLE AS WATER WITH ETANOL AS NECESSARY, WET COMP ONLY AS NECESSARY. DO NOT STORE COMPS WITH UNPROTECTED IRON FOR A LONG PERIOD OF TIME.