For peak scientific precision, use a pencil to mark the quarter and halfway points along the tube. This will show you how much of the tube to burn.
Watch out for stray bits of paper. If you see any, stamp on them or drip water on them so that no fires start.
Make sure to soak the paper in water when you’re done with it to avoid starting a fire. To produce black smoke, burn the end with the rubber band. It will smell horrible.
If using a cold pack, make sure to get one that contains pure ammonium nitrate rather than a substitute material such as urea.
If the water pack breaks, you will use up the chemical properties of your ammonium nitrate and will need to use a different pack for the experiment. Gloves should protect your skin from ammonium nitrate’s toxicity. If you do get any on your skin, halt your experiment and wash your skin thoroughly with water.
Soak individual sheets until all the solution is absorbed. Drying may take several hours.
You can make several small smoke bombs with individual sheets of paper, or one large smoke bomb that will last longer.
The flame should burn slowly and should not be visible through the smoke. Douse it in water when you are finished.
Make sure there is water and a fire extinguisher nearby so that you can douse a runaway fire. Don’t build a signal fire unless you are actually in need of help!
For wet foliage, gather leaves, weeds, and grass. If they are not damp, pour a few cups of water along them.
Add more tinder as the fire goes. Blow gently at the base of the fire to encourage it. When you have strong fire, you can add more kindling or fuel to keep it going.
If you do this in a remote location, you may attract rescuers. Alternatively, add a paper bag of wet straw. You’ll get a smaller but longer-lasting plume. Douse the fire thoroughly with water when you are done. Check on it after the steam clears to make sure it isn’t still burning, sparking, or smoking.
