acrylic varnish, picture varnish definition

A varnish employed as the last surface coating on an dried oil painting.  The varnish serves as a preservation and protection mechanism and gives the painting a glossy look.  Two important varnishes for painters include damar varnish and clear acrylic (methacrylate) varnish.  Damar varnish gives the painting a bright gloss finish.  And clear acrylic varnish gives paintings a satiny or mat gloss.  Over time paintings need to be cleaned because of dirt/dust/grime from the environment.  Ideally a picture varnish is easily soluble in a mild solvent (such as mineral spirits) so dirty varnish can be taken off using careful conservation methods.  Damar varnished has replaced mastic varnish (used in the 19th century) because of its resistance to bloom, yellowing over time and features a duller gloss.  Damar varnish may be used in thin coats.