Grind charcoal briquettes into a fine powder using a mortar and pestle. Place one to two briquettes in your mortar and apply pressure to the chunks using your pestle. Gently twist to separate individual carbon particles.
Measure your ingredients. You will need 75 parts saltpeter, 15 parts charcoal and 10 parts sulfur. Parts are weight measurements that are equal to 1 1/2 ounces for each one part. Conversion would make your measurements 112 1/2 ounces of saltpeter, 22 1/2 ounces of charcoal and 15 ounces of sulfur.
Clean your mortar and pestle and grind your saltpeter. Once your saltpeter is of a fine consistency, clean the mortar and pestle again and grind your sulfur to the same consistency.
Mix your ingredients in a small bowl. Add small amounts of distilled water until your mixture resembles biscuit dough. It will be thick and crumbly.
Place small amounts of your mixture into a sieve. Pour alcohol over the mixture. Alcohol increases your powder's potency but is not necessary. Continue with small amounts of mixture until you have treated the entire batch. Place your prepared mixture into a separate container.
Shape your mixture into individual rectangles, much like modelling clay. Allow to air dry completely.