Which of the following is an example of a drier used in varnish?
The Role of Components in Varnish
Varnish is a coating made from a few key ingredients. To identify them, it's essential to know their function. The Resin is the solid that forms the protective film. The Solvent is the liquid that dissolves the resin, allowing it to be applied. The Drier is a special additive that acts as a catalyst to make the varnish harden faster.
📝 Detailed Analysis of the Options
(a) Mastic, (b) Shellac, & (c) Amber
Component Type: Resin.
Function: Mastic, Shellac, and Amber are all examples of natural resins. They are the primary film-forming solids in traditional varnishes. They are dissolved in a solvent to create the liquid varnish. When the solvent evaporates, these resins are left behind to form the hard, transparent coat. They are the main ingredient, not the drying catalyst.
(d) Lead acetate
Component Type: Drier.
Function: This is the correct answer. Lead acetate is a metallic salt, and like litharge (lead oxide), it is used as a drier in oil-based paints and varnishes. It acts as a catalyst, significantly speeding up the chemical reaction (oxidation) that causes the oil in the varnish to dry and harden. Without a drier, some varnishes could take days or weeks to cure properly.
📊 Main Components of Varnish
| Component | Role | Examples |
|---|---|---|
| Drier | Speeds up drying (Catalyst) | Lead acetate, Litharge, Manganese Dioxide |
| Resin | Forms the solid, protective film | Mastic, Shellac, Amber, Copal |
| Solvent | Dissolves the resin to make it liquid | Turpentine, Alcohol (Spirit), Mineral Spirits |