Acetone (dimethyl-ketone)
A colourless liquid, with a characteristic odour, produced during the dry distillation of wood and other organic bodies. It is miscible with certain oils, water, alcohol, and ether, and is an excellent solvent for many substances mentioned specifically elsewhere. It has an extremely low flash-point which makes it dangerous to use near a naked flame.
It is probably the most powerful existing solvent for many kinds of varnish. The writer has found it dissolves varnish films which resisted all the more usual solvents, but its action was extremely rapid and not entirely predictable, and its use needed great care. Dilution slows the rapidity of the action, but it would be much better not to use it on valuable objects until experience has been gained. Its action can be stopped by applying kerosene. For important work re-distilled acetone is needed, otherwise the commercial grade is suitable.
Acetone varnishes are made from celluloid dissolved in a mixture of acetone to which a little ether has been added. Some contain a trace of castor oil in addition to increase the elasticity of the film. They need to be used with care, and are inclined to strip off some materials in the form of a film. Such varnishes are apt to discolour.