Warning: Doing this can result in injury and possibly death if made in large quantities. Do not try unless
you are taking the neccessary safety precautions such as wearing goggles, a jacket, gloves, and having
a fire extinguisher nearby.
The traditional ratios for ancient Chinese gunpowder involves potassium nitrate, charcoal, and sulfur. You can get potassium nitrate in bottles of stump remover and sulfur from the gardening section at a Lowes or another hardware and home store. You can also order sulfur and potassium nitrate online from amazon. You can obtain charcoal by buying grill charcoal and crushing it into a fine powder. The finer and purer the ingredients means the better your homemade black powder will be. My first time making black powder I used impure sulfur and not very fine charcoal but I was still able to get it too work in a homemade firecracker.
First you want to grind up all the materials INDIVIDUALLY into a fine powder.
Then mix them together in the ratios of:
75% potassium nitrate
*the ratios are by weight which means you weigh them out on a scale, a 100 gram batch would be 75 grams potassium nitrate, 15 grams of charcoal, and 10 grams of sulfur.
When you are done mixing store in an airtight container because potassium nitrate is hydrophilic which means it takes moisture in from the air which has a negative impact on black powder. When igniting your homemade black powder use a fuse or another method which is safe. Be careful! Black powder is dangerous!