I've done a little MSDS research. Brake cleaner isn't just brake cleaner. The chlorinated formulations (with carbon tetrachloride, 1,1,1-trichloroethane or similar compounds), are really dangerous if ignited or heated above decomposition temperature, due to the possible generation of phosgene and any number of dangerous chlorine compounds(dioxin, anyone?). I think these are now very rare or banned in Europe and the US. The aerosol cans may still carry the relevant warnings as a public safety measure (so people don't go about assuming old cans of brake cleaner are also safe to spray onto hot surfaces). Not that the new stuff is safe to spray on hot surfaces either- the flashpoint is a rewardingly low -97C and the ignition temperature a mere 200C. The modern formulations tend to contain only naphtha, IPA and acetone, with either carbon dioxide or butane propellant. The ones with butane propellant ought to be wonderfully flammable. Note that they usually use 'light hydrotreated naphtha', CAS 64742-49-0 with a maximum boiling point of around 60C. This should be almost entirely benzene-free (concentrations for commercial products seem to indicate benzene content as '< 1ppm') given that benzene boils at 80C. Any product with appreciable benzene content needs to be labeled as 'poisonous' rather than merely 'irritant' and would almost certainly not be legal as an aerosol formulation for purchase by the general public. This one seems to tick all the boxes for a product to experiment with in cheap Chinese flame machines without running risks of anything more serious than third-degree burns.... http://www.rapidonline.com/1/1/4716-brake-cleaner.html You may be rather crispy, but you probably won't have cancer, or melt your lungs with WWI poison gases. BTW general disclaimer. I am not responsible for the state of your eyebrows or the number of skin grafts you may require after trying this out. In fact, I strongly advocate you don't try this at all, or find a suitably risky displacement activity like hang-gliding or joining the armed forces instead.
