Electronics, Embedded Systems, and Software are my breakfast, lunch, and dinner.
I am not in any way responsible for injury or damage resulting from this blog entry. Do not assume that these instructions are either complete or correct. Don't be stupid either; if you can't handle fire safely then you surely can't handle this safely.
Lately I have been doing small weekend projects which are generally cheap and fun. This past weekend's project, in honor of the 4th, was making smoke bombs. I found out from a friend at work that there was a store in milwaukee which sold lab supplies, including KNO3 (saltpeter). I have been wondering how to aquire that chemical since I first read the anarchist's cookbook a few years ago. It is the main ingredient in many pyrotechnical compounds including gun powder, flash powder, and smoke bombs. So, I went to this store (Laabs, Inc.) in Milwaukee, near 30th and Wisconsin and bought two pounds of this chemical @ $7.12/lb. I got carded before I could buy it, so it is an over 18 sort of substance. It looks kind of like the rouded kind of rock salt that you can buy for water softeners.
The next ingredient was easy to get: brown sugar. I got the light brown kind, but apparently the dark brown kind works better. It cost me $1.89 at Pick'n'save (so far we are up to ~$18 on this project). Now that I have introduced the main ingredients, here is the illistrated tutorial:
Saltpeter or KNO3. It doesn't matter which since they are the same thing.
Brown sugar. Dark brown is best, but white and light brown will also work just not as well.
A scale of some kind. I used a postage scale.
A mortar and pestle-like device. I used a baby food jar and a small piece of floor molding...anything will work as long as it isn't made of metal. It isn't like we have sparks to worry about like if we were making flash powder, but I think not using sparking materials would be a good habit to get into.
Something to put it on. This has to be able to withstand rather high temperatures and it will be stained black. I originally used 4 layers of aluminum foil on our driveway until I realized that a single smoke bomb was melting straight through the 4 layers down to the driveway. I used a flowerpot for the video at the end (it did crack). Sand also works since you can just bury it when you are done.
Weigh out the saltpeter and place it into the mortar. It is best to weigh it while it is inside the mortar so that it doesn't get all over the place from dumping into the mortar. Since this mixture is going to be 3 parts KNO3 to 2 parts sugar, it is easiest to make this a number divisible by 3. In this tutorial I used 48g of saltpeter.
On a paper towel, weigh out the sugar. With 48g of saltpeter I had to weigh out 24g of sugar.
Smash the saltpeter in the mortar until it is a relatively fine powder. Do not breathe the powder since saltpeter can cause medical issues including lung irritation and impotence (yes, I said impotence).
After removing the sugar from the scale, place it on a hard surface and pour the saltpeter onto the paper towel. Mix them throughly.
After mixing, fold the paper towel over the mixture to make a packet.
Place the packet onto a surface to light it on and put a bit of rubbing alcohol over it. It helps to make a "fuse" out of another paper towel, soak that in alcohol, and lay it across. Make sure not to get the mixture too wet since it isn't nearly as potent when it is wet.
Light the alcohol. After a few seconds there should be a hissing noise and then smoke. If the paper towel burns away during the hissing noise, the boiling greenish mixture may be observed, but be careful not to get too close. The splatter from the boiling stuff does hurt (it is quite hot) and the smoke isn't too good to breathe in.