H3 is a pyrotechnic composition which is mostly used as burst charge for small diameter shells. It is friction and shock sensitive, as are most compositions containing chlorates and should not get in contact with either sulfur, sulfides, sulfates or ammonium perchlorate. The name "H3" refers to the traditonal composing of three parts hemp charcoal for every ten parts of potassium chlorate.
This energetic burst charge is used for small diameter shells (2...3 inch), since it makes a large and symmetrical burst possible. Besides the composition below, a ratio of chlorate to hemp coal of 10:3 is also popular. The sensitivity of this mixture to shock and friction is unexpectedly low, as long as the composition does not come into contact with sulfur or sulfur compounds.
Method: The two components must be milled to a fine powder. The fineness of the charcoal is particularly important for good results. Using a more resctive charcoal will cut down on your milling times. The two components must be milled seperately. Sieve the fine chlorate onto a large sheet of paper. Discard residue left on the sieve; dont push it through. Then add a small amount of the charcoal, and mix it by hand until it is uniform. This will stop the chlroate from clumping. Now sieve the chlorate together with the remaining charcoal at least four times. Dont push or rub it through the sieve. Once agian, discard any residue. Finally repeat to add the binder. Never rub dextrin with chlorate through the sieve. This can then be coated onto rice hulls or some other nucleus to form burst charge, suitible for shells upto 4" diameter. The composition should burn much faster than black powder, with few sparks. If not, the charcoal is not fine enough.