It’s important that you use celluloid ping-pong balls instead of plastic ones. You can tell the difference between the two because the plastic balls are shiny and bend easily. The celluloid ping-pong balls are typically more durable and matte. [2] X Research source
The only purpose of the pencil in this step is to create a mold for the foil, so do not completely cover it. Make sure there is a hole in the foil at the end of the pencil so you can take it out when you’re finished.
Use an old cast iron skillet that you don’t plan on cooking with in the future. The potassium nitrate mixture may ruin it. You can get potassium nitrate, also called saltpeter, at your local garden store or online. It’s important to wear your safety gear. Contact with potassium nitrate can cause eye and skin irritation. Breathing it in can irritate your nose and cause sneezing and coughing. [11] X Research source
Do not overcook the mixture and take care not to set it on fire. If it starts to smoke in the pan, turn the heat down immediately.
When you’re pouring the mixture in the cardboard tube, make sure to pack it tightly. If it’s not, the smoke won’t burn smoothly when you light the smoke bomb.
Potassium nitrate smoke bombs burn very violently. So make sure you place it in a clear, open area away from anything that can catch fire.
Wear gloves when you handle the granules. Ammonium nitrate is not incredibly toxic, but if it gets on your skin, wipe it off, and rinse the skin immediately. Always wash your hands thoroughly with liquid soap when you are finished. [22] X Research source
Stop adding water as soon as you notice all of the granules have dissolved so the solution is still concentrated. If you add too much water, you’ll end up with bombs that don’t smoke.
Try to find an older newspaper. Brand new newspapers have a waxy film that prevents them from lighting properly.
The wet newspaper will be fragile, so be careful not to rip it while handling.
You can tell when they are ready when they can be lifted off of the pavement easily.
You may opt to experiment with different lengths and widths for your smoke bomb. If so, cut up the newspaper sheets, rip them in half, or leave them whole before rolling them up.
