Varnish is a solution of some resinous substance in alcohol, oil or turpentine. The process of covering the surfaces with varnish is known as varnishing. Varnishing is done only on wooden surfaces.
Advantages of Varnish:
- It brings about brilliance to the painted surface.
- It protects the surface against adverse effect of the atmosphere.
- It increases the durability of the paint film.
- It beautifies the surface without hiding the beautiful grains of the wood.
Varnish plays an important role in finishing wooden surfaces of doors, windows, floors, furniture etc.
Properties of a good Varnish:
- Varnish should not shrink or show cracks after drying.
- The thin film of varnish should be tough, hard and durable.
- The natural colour of varnish should not fade away when surface is exposed to the atmospheric actions.
- It should make the surface glossy.
- It should dry rapidly.
- It should impart the surface uniform colour and pleasing appearance.
- It should not hide the natural grains of the surface.
Types of Varnish:
There are seven types of varnish depending upon the solvent used.
- Oil varnish: Oil varnish forms a hard and durable film, but they dry slowly.
- Spirit varnish: This varnish dries very quickly and gets easily affected by weather action. It is mostly used for wood furniture.
- Turpentine varnish: It is light in colour and dries quickly. It is not as tough and hard as Oil varnish.
- Water varnish: This varnish is used for painting pictures, posters and maps.
- Asphalt varnish: It is used for varnishing fabricated iron and steel products.
- Spar varnish: This varnish is very good weather resistant. It is mostly used on spars and other exposed parts of the ships. It is not used indoors.
- Flat varnish: This varnish presents a dull appearance.