Hairspray Depending on what type you use, most hairsprays are pretty standard and gum up your cannon pretty easily.  I recommend that you use the White Rain brand Propane Propane works great and doesn't gum up your cannon. Butane Pretty much the same as propane Carburetor/Lighter Fluid  Packs some the most powerful punches yet is harder to dispense Denatured Alcohol Hard to get to light. Very Powerful Acetylene  Very Dangerous yet the strongest stuff out there.  I don't suggest that you use it unless you are willing to take your life into your own hands for acetylene has the power to shrapnalize your chamber completely if the projectile is stuffed in too tight  Bug Sprays Most bug sprays work well but be careful which ones release toxic vapors. Static Guards Same as Bug Sprays Aerosol Right Guard Works great and smells great Note: I have not actually tried all these propellants, though I have tried most of them.  This list is based on the attempts of other fellow spudgunners.  If you are just beginning this sort of stuff, stick to the hairsprays, and Bug Sprays rather than propane and acetylene.