---
title: "Short note: Varnish"
subject: "Engineering Chemistry"
chapter: 8
key: "semester_2/engineering_chemistry:varnish-note"
source: https://www.bctengineer.com/q/semester_2/engineering_chemistry/varnish-note
site: BCT Engineering
---

# Short note: Varnish

Engineering Chemistry · Chapter 8: Lubricants and Paints

- Asked in: 2067 Chaitra, 2 marks
- Video: [Composition of Varnishes, Chemistry Lecture | Sabaq.pk](https://www.youtube.com/watch?v=Keff0zA7Zq8) — Sabaq Foundation - Free Videos & Tests, Grades K-14
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_2/engineering_chemistry/varnish-note
- Whole chapter: https://www.bctengineer.com/md/semester_2/engineering_chemistry/chapter-8

## Question

Write a short note on varnish.

## Short answer

Varnish is a resin solution in oil/solvent, drying to a transparent, glossy film. It is used on wood and over paint for protection, and differs from paint by containing no pigment.

## Answer

**Varnish** is a homogeneous solution of a resin (natural: shellac, copal, amber, rosin; or synthetic) in a drying oil and/or a volatile solvent like turpentine or alcohol. It contains no pigment. After application, the solvent evaporates and the oil dries by oxidation to leave a **transparent, glossy, hard** protective film.

- **Types:** oil varnish (resin in linseed oil + turpentine, slow-drying, durable), spirit varnish (shellac in alcohol, quick-drying), water varnish.
- **Constituents:** resin, drying oil, thinner, and drier.
- **Uses:** coating wooden furniture, doors, floors and instruments; over paint to give gloss and protection. It brings out the natural grain of wood.
- **Difference from paint:** varnish is transparent (no pigment) while paint is opaque and coloured.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. How does varnish differ from paint?
   A. Varnish is opaque and paint is transparent
   B. Varnish is water-based only
   C. Both contain pigment but different oils
   D. Varnish has no pigment so it is transparent; paint is opaque and coloured
   Answer: D. Varnish contains no pigment. (Key point: Varnish vs paint)

2. How is the varnish film formed?
   A. The pigment settles out
   B. The solvent evaporates and the oil dries by oxidation
   C. The resin burns off
   D. The water freezes
   Answer: B. A transparent, glossy, hard film remains. (Key point: Film formation)

3. Which is spirit varnish?
   A. Resin in linseed oil, slow-drying
   B. Resin in water
   C. Pigment in alcohol
   D. Shellac in alcohol, quick-drying
   Answer: D. Oil varnish is slow-drying and durable; spirit varnish is quick-drying. (Key point: Types)