How To: Make a Simple Fog Machine to Prank Your Roommates

Like theme music, I always feel that I need more fog in my life. Fog can be useful for many reasons—warding off smaller siblings from your bedroom, keeping curious hands out of your cupboard, and tricking your friends into thinking there's something horribly wrong with their vehicle. So, today we'll be making a very simple fog machine for small scale applications.

Materials

• Distilled water
• Glycerin (aka glycerine or glycerol)
• Tin can (or pie tin)
• Hot plate, Bunsen burner, or candles

Aside from explosives, glycerin is used in baking and medicine. If you look for yours at the pharmacy, be prepared for an awkward interaction with the sales person, because you can only find it in the suppositories section, as either emollient or laxative.

"It's for science," I told the woman behind the counter.

Step 1: Set Up Heating Mechanism

Because I don't have a hot plate or Bunsen burner, I had to improvise this heating setup with some candles, scrap wood, and bolts. You can use any hot plate—even a camping stove.

Step 2: Mix Concoction

Mix one part glycerin with three parts distilled water. You don't need a lot for a bunch of fog. Start with a small glass and work up from there, if you need for more.

At first, the mixture will appear cloudy. Stir it for 20 seconds and it should be totally clear.

Step 3: Heat and Pour

Place your tin can (or pie tin) over the flame or heat source and let it heat up for a few seconds. Place a drop of your solution on the plate and see what happens. The more you place, the longer it takes to evaporate and create fog. The amount of fog depends on the surface area of your container and the even distribution of heat and solution over that surface area.

A tiny amount of solution evaporates quickly.

Step 4: Improvements and Limitations

The simplest way to improve output after maximizing surface area is to concentrate the fog with a funnel shape. Additionally, you can totally block up the fog container and store it up until a sufficient amount has gathered. This could be useful in combination with a motion sensor that spews fog at unsuspecting horror struck innocents.

Because the fog is heated vapor, it rises up into the air. It is not possible to make a thick ground fog with this device, if you are looking to cover your floor in a carpet of fog. This will work better for fog effects in candy bowls, cars, closets, or any kind of enclosed area.

This project is simple enough to do several times in an afternoon. What creative places can you think of to put this fog maker in?