XII Chemistry BIEK Topic - Varnish (Short Note)

Varnish (Short Note)
Varnish is a mixture of resin, volatile organic solvents and drying oils. To prepare Varnish such as resin (plastic in liquid state) is dissolved in volatile organic solvents, such as ether or alcohol and then drying oil such as linseed oil is added to it.

The drying oils such as linseed oil consist of esters of highly unsaturated acids containing two or more double bonds. When exposed to air, these oils absorb oxygen and form hard and tough film. The film is insoluble in water.

When a Varnish is applied to the surface, the volatile organic solvents evaporate quickly and the drying oil absorbs oxygen and a hard tough glossy film is obtained. The glossy appearance of the film is due to the presence of resin. Varnish differ from paints in such a manner that, it does not has any added pigment.