Varnish

Varnish is a combination of a drying oil, a resin, and a thinner or solvent plus a metal drier to accelerate the drying. After being applied, the film-forming substances in varnishes either harden directly, as soon as the solvent has fully evaporated, or harden after evaporation of the solvent through curing processes. There are many different types of drying oils, including linseed oil, tung oil, and walnut oil that are used in varnishes and the resins can be amber, kauri gum, dammar, copal, rosin (colophony or pine resin), sandarac, balsam, elemi, mastic, and shellac. Varnish also can be created from synthetic resins such as acrylic, alkyd, or polyurethane, and Epoxy. Solvents that are used in varnishes mostly are white spirit, paint thinner, and mineral spirit.