Elaborate breathing equipment has to be used, and you can absorb some toxic liquids through you skin. Crosslinked finishes, such as CAB, catalyzed lacquers, and conversion varnish are all very dangerous. Polyester is among the worst. Even the common urethane lacquer and nitrocellulose lacquers are dangerous. And if the fumes don t kill you, the flames might.
Many finishes are highly flammable.
Shellac, with an alcohol solvent base, is a common fire hazard, as are most finishes without a water base. Moisture cured polyurethane is both flammable and very hazardous. Most of the auto finishing products used by cuemakers are hazardous, or very hazardous in gaseous or liquid states. Even something as simply as an oily rag can ignite spontaneously, without any spark or flame needed to set it off. If you work at home and the shop burns down, the homeowner s policy won t cover it.