In estimating the quality of a varnish the following points must be considered: - 1. Quickness in drying; 2. Hardness of film or coating; 3. Toughness of film; 4. Amount of gloss; 5. Permanence of gloss of film; and 6. Durability on exposure to weather.1
The quality of a varnish depends almost entirely upon that of the ingredients it contains.
Varnish is used to give brilliancy to painted surfaces and to protect them from the action of the atmosphere, or from slight friction.
Varnish is often applied to plain unpainted wood surfaces in the roofs, joinery, and fittings of houses, and to intensify and brighten the ornamental appearance of the grain. It is also applied to painted and to papered walls.
In the former case it is sometimes flatted so as to give a dead appearance, similar to that of a flatted coat of paint.