To make our smoke bombs we first need to make the casings. Start by measuring out some two inch sections of cardboard wrapping paper tube, and then cut them out carefully with a razor knife, trying to make the cuts as straight as possible. We’re going to reinforce these tubes. Using the prototype barrel from the cardboard rocket rifle video as a stand, I placed each 2″ tube over it and then wrapped them in several layers of red duct tape. This will help keep them rigid.
Now we’re going to glue these sections of tube to a piece of thick cardboard. Using a hot glue gun, make a thick bead of glue around the edge of the tube and then press it firmly into place on our cardboard sheet. Let them dry for a bit, and once you cut them out they should look like this.
In order to make our fuel we’re going to need some potassium nitrate. I found this stump remover at Home Depot, and according to the label it is 100% pure, so it should work perfect! Using a gram scale we need to measure out 40% sugar and 60% potassium nitrate. Its important to be fairly accurate with this, so take your time. I added a tablespoon of orange fabric dye for effect, but its purely optional.
Now I moved outdoor for the cooking portion, setting my outdoor side burner on medium-low heat. Be sure to use a pan that you don’t care about for this project as you won’t want to use it again for food. Carefully and evenly pour the 40% portion of sugar into the pan, and then immediately pour the 60% portion of potassium nitrate over the top. Using a heat resistant rubber spatula, slowly start folding the mixture in on top of itself. After a couple of minutes it will start to turn brown as it caramelizes and will quickly become a nice gooey consistency.
At this point you can turn the heat down and use a spoon, preferably one you don’t care about to start packing your cardboard tubes with the mixture. Make sure there are no air pockets in the tubes, as this could cause them to explode later on. And your smoke bombs are complete! Just let them cool for a couple of hours.
Once again, when we’re dealing with combustibles, eye protection is not optional. Using a portable torch I lit my first smoke bomb and it quickly erupted into a huge billow of smoke. That’s awesome! I used a ceramic stone to protect my patio deck from scorch marks and lit off my second smoke bomb. I sure hope my neighbors don’t call the fire department because the smoke output of these things is incredible.
Notice I’m doing this outdoors in a well ventilated area. These things put off a lot of heat, and the burning casings take a long time stop burning and cool down. I eventually poured water on them to put them out. I had some leftover goo from the cooking process, so of course I had to burn that too! Well if you have an idea for a future video, leave it in the comments, and if you enjoyed this project please help me out by liking and subscribing to my channel on YouTube.