"Smoke bomb" is a rather poor name for these because they don't explode, but that's the name most people know them by, so that is what I will use. These are very easy to make and are a good entry into pyrotechnic mixtures.
Note: There are of course many different smoke compositions that can be made (just check the Composition Database section on Smoke Compositions), but this is the simplest one.
Materials:
Powdered potassium nitrate (kno3)
Sugar (commonly called sucrose, can be powdered or granulated)
Procedure:
Simply mix the two ingredients together in a 6/4 ratio of kno3/sucrose. You can mix the two just by putting them in a sealed container and shaking it. It is not a sensitive mix and does not have to be perfectly mixed to work. The ratios do not even need to be accurate, and this is one mixture you can easily get away with measuring by volume on. Just use 6 scoops of kno3 and four scoops of the same size of sucrose. It can be used in the dry powder form, or for better results, melted (where is can also be used as a rocket propellant).
Melting procedure:
Melting the ingredients together will improve performance, but is a lot more risky than dry mixing. I just used a modified version of the instructions I found on this page. Read step #8 for instructions. I've heard of MANY accidents with doing this, all caused by melting the mixture directly on a stove rather than using this "two stage" process. Always perform this step OUTSIDE and WEAR GLOVES to protect you hands in case the mixture accidentally ignites (It shouldn't using this method, but could if something spills. If nothing else, they will protect you from splashing hot crisco on yourself.) Ideally an electric heat sourse would be used instead of one involving flame (I don't have an electric hotplate yet, but plan to get one).
These kinds of mixtures can be melted on direct heat, but only if done at low heat and very slowly. An electric heat source should be used for this and I will test it once I find a cheap hotplate to buy.
Melting kno3/sucrose:
For a comparison of powder mixed vs. melted, click here.
Use:
No special casing is needed, you could even just pour it in a pile and light it if you want. If you want durability, use a cardboard or plastic casing. If you are cheap like me, you can just use paper or a tissue. Just pour the powder into the middle of the square of paper, stick in your fuse, fold up the paper and tape it. Cheap match head/masking tape fuse can be used with this, the mixture ignites easily with flame or a fuse.
Match fuse lit:
Smoke produced:
Residue after burning:
