Bubbles are fun no matter what, but bubbles you can burn just has that added extra appeal. Here's an easy science project you can do that proves propellants in common products are flammable and allows you to burn some bubbles.
Materials for the Burning Bubbles Project
- soapy water or bubble solution
- spray can containing a pressurized flammable propellant
- lighter or match (preferably long-handled)
- cup or bowl
A lot of the products you use that come in spray cans use a flammable propellant to disperse their product. Examples include hairspray, canned air, spray paint, antiperspirant, and bug spray. Common flammable propellants include various alcohols, propane, n-butane, methyl ethyl ether and dimethyl ether. You know you have a can containing a flammable product by reading the label. It will include a hazard statement warning you that the contents are under pressure and to keep the can away from heat and flame and that the contents are flammable. Some cans use non-flammable carbon dioxide or nitrous oxide as a propellent (whipped cream and cooking sprays), which won't work for this project. Once you have identified a flammable propellant, one fire-related project is to spray the product and ignite the aerosol, creating a sort of flamethrower. This is not particularly safe. Blowing flammable bubbles and igniting them illustrates the same point without the risk of blowing up a pressurized can.
Blow Bubbles and Burn Them
- Pour soapy water or bubble solution into a container.
- Immerse the nozzle of the can in the liquid.
- Spray the can, forming bubbles.
- Remove the can from the liquid and set it a safe distance from the container.
- Ignite the bubbles, preferably using a long-handled lighter.
Do you see why it would be a bad plan to smoke while using hairspray? The effect you get depends on the flammable propellant. The flames don't last long enough (at least in my experience) to set off a smoke alarm or melt a plastic container.
This is one of those projects which should only be attempted under adult supervision. Do not
get carried away and blow a big mass of bubbles. Igniting flammable materials is associated with risk. Use of proper eye and skin protection is advised.