Varnish is a transparent, protective coating added to a painting when it is finished and completely dry. It protects against pollution (smoke, dust), abrasion on the surface, and fading through exposure to light (ultraviolet radiation). Varnish can be applied by brush or sprayed on.
Varnish also evens out the glossiness of a painting, or can be used to give it a matte finish. Check the label on the varnish to see whether it's gloss or matte (or satin, which is semi-matte).
Depending on the type of varnish used, it may be removable or not. Again the label will tell you. Art conservators prefer removable varnish because it can be renewed and replaced easily if it yellows or becomes dirty from environmental pollution.
Final varnish is different to retouch varnish, which is used as a temporary varnish on an oil painting while it dries.
See Also:
• How to Varnish an Acrylic or Oil Painting
• Why Varnish a Painting?
• Using an Isolation Coat Before Varnishing
