Difficulty: Moderately Easy
Tips & Warnings:
- good containers are paper towel tubes, kleenex boxes, tin foil bowls, small cardboard boxes, newspaper taped in a cone shape, or 2 layers of paper towel or kleenexes taped into a bag shape.
- the smoke created is not toxic but still shouldn't be used indoors or other areas with poor ventilation
- Be careful not to inhale a lot of KNO3 at any point
- Be careful not to stand too close when it's burning or you may get burned
- If any carbon, sulfur, or especially both comes in contact with the material while burning, it can case a massive explosion
Step1
First make sure all your ingredients are acceptable. The Potassium Nitrate (KNO3) should be pyrotechnics grade. If you're using stump remover which is around 98% KNO3, the other ingredients may cause unexpected effects. You can get pyrotechnics grade KNO3 on Ebay, at chemistry stores, or from other online retailers. The containment material such as tin foil or a paper towel must be thick enough to transport your ingredients to the lighting sight. If necessary use two or more layers of paper towels or a cardboard box. Whatever containment material you use, make sure it can be incinerated without anything bad happening (so not plastic). For safety, it should also not contain a lot of carbon or sulfur. It also can't hold pressure while the smoke bomb is burning or it will explode like a grenade. So use an open topped box or tin foil bowl for example instead of a pop can. The powdered sugar should be as pure as possible with no additives. If you're using a fuse, make sure it's not the super fast burning type if it's short.
Step2
Measure out the KNO3 and powdered sugar in a ratio by weight of 3 parts KNO3 to 2 parts powdered sugar. So if you're using 3 pounds of KNO3, use 2 pounds of sugar. Or 1 pound of KNO3 would need 2/3 pound powdered sugar
Step3
Make sure you have some sort of breathing protection equipped before mixing. Potassium Nitrate is a depressant and can kill you if way too much is absorbed into the blood stream. In small amounts, it's not damaging at all even if swallowed though. I would recommend pulling your shirt over your mouth or using a bandanna or scarf as a filter. If your containment material is strong enough to withstand stirring, pour both ingredients in together. If not, put both ingredients in a separate mixing container. It helps to add a little of each and alternate instead of dumping all sugar in first for example. That will make mixing easier. Use a spoon or other tool to mix the two materials as thoroughly as possible. Since both are white, it's hard to tell when they're mixed so just mix it for several minutes in all different patterns. If the mixture isn't completely mixed, it won't burn properly. If you want slower, slightly less dense smoke and less flame, add baking soda and mix thoroughly. The amount is variable depending on the desired burn speed but on average, it should be 1/6 of the total weight. But if you want a fast, glowing mushroom cloud burning as quickly as possible, don't add any.
Step4
If you used a separate mixing container, pour the mixed contents into your containment material. If using tin foil, it works well to form a bowl shape with it. If you are using something weaker like paper towel, you can lay it out flat and pour the mixture onto it. Then pick up all four corners and lift them up together and put a rubber band or tape around the middle to hold it closed. If you are using a fuse, insert a half inch or more into the mix. For a slower burn, make sure the mixture is spread wide across the bottom of the container and not very high. For the slowest burn put it in a paper towel tube or similarly shaped container. For the fastest burn, make sure the mixture is as close to a cube or sphere as possible.
Step5
Now your smoke bomb is all set. Transport it to the lighting area. I'd suggest putting something disposable like wood under it to protect grass, concrete, or asphalt from damage. This smoke bomb is easily hot enough to melt a hole in a blacktop road so be very careful. Black residue may shoot off a foot or two and is hard to remove from concrete also. If you're using a fuse, light it and get at least 15 feet away. Large smoke bombs (5+ pounds total) can cause flash burns at 10 or less feet so stand much further away if it's large. If you use a flammable material for containment such as a paper towel, you can light that and get away instead.
Authority 
Comments
WiredFiend said
on 7/7/2008 http://youtube.com/watch?v=j5ddLYJ-Zkg&feature=related
http://youtube.com/watch?v=GviK0fm9U3I
You all may find these videos helpful as well, especially the second one which is a how-to on how to make a full-ring igniter for the smoke grenade.
WiredFiend said
on 7/7/2008 BTW, to all the reader out there - Toilet paper rolls work best - unless you're gonna pull off a massive one like the 17-pounder in this guys video lol. Never know when you're gonna need a smoke screen in a wide open 100 acre plain. lol - btw - can you tell some sites where I can get KNO3?
WiredFiend said
on 7/7/2008 Why someone might need/want to know this? Because it's a fun and convenient way to create a large quantity of smoke, for use either as a signal, in emergency situations, or as cover for an airsoft or paintball war. Or maybe if you just wanna make smoke for the heck of it. Or if your a do-it-yourself kinda person who likes to do things hands-on, or just want something to say "Hey, I made this!" How he knows this? Well, theres lots of other how-to guides of how to make a smoke bomb, (This being the most helpful and informative - Thumbs up!) or maybe he just payed attention in chemistry class, and had a few goes at it until he got it right!
amylaine said
on 5/19/2008 I wont ask how you know this or why some one needs to know this.