Varnish is a clear, transparent, hard protective coating or film that is primarily used as a wood finish where the distinctive tones and grains in the wood are intended to be visible. It is not to be confused with wood stain, although it may be pigmented as desired. Varnish finishes are naturally glossy, but satin/semi-gloss and flat sheens are available. Varnish is a specific combination of resins, oils, and solvents that creates a translucent, highly protective coating when applied to wood. It cures into a hard, glossy, and transparent film, although versions tinted in various sheens and hues are available. Its main purpose is to seal and protect wood products while showing off the wood’s distinctive grain and natural beauty.
Varnish is traditionally a combination of a drying oil, a resin, and a solvent. The word "varnish" comes from Mediaeval Latin vernix, meaning odorous resin, perhaps derived from Middle Greek berōnikón or beroníkē, meaning amber or amber-colored glass. The early varnishes were solutions of natural resins that are the secretions of plants, such as dammar, copal, and rosin. Nowadays, many different types of varnish have been created to serve a variety of different purposes.
Varnishes are not only used as wood finishes, but also as protective coatings for wooden surfaces, paintings, and various decorative objects. They intensify the appearance of pigments on the painting surface by the refraction of light, a process called "saturation". Although varnishes are traditionally clear, they can be toned or altered with the addition of pigments and other materials. Toned varnishes may be utilized to balance a painting whose appearance has changed with age.
