---
title: "Paint and requisites of a good paint"
subject: "Engineering Chemistry"
chapter: 8
key: "semester_2/engineering_chemistry:paint-requisites-short"
source: https://www.bctengineer.com/q/semester_2/engineering_chemistry/paint-requisites-short
site: BCT Engineering
---

# Paint and requisites of a good paint

Engineering Chemistry · Chapter 8: Lubricants and Paints

- Asked in: 2072 Asoj, 3 marks; 2067 Mangsir, 1+2 marks (asked 2 times)
- Video: [Characteristics of a Good Paint, Chemistry Lecture | Sabaq.pk](https://www.youtube.com/watch?v=uMqqopX29yg) — 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/paint-requisites-short
- Whole chapter: https://www.bctengineer.com/md/semester_2/engineering_chemistry/chapter-8

## Question

What is paint? Give the requisites of a good paint.

## Short answer

Paint is a dispersion of pigment in a drying oil. A good paint spreads easily, dries to a hard elastic film that adheres without cracking, resists weathering and chemicals, has stable colour, and is non-toxic and economical.

## Answer

**Paint** is a mechanical dispersion of one or more pigments in a drying oil (vehicle) with a thinner, drier and other additives. When it is applied to a surface, the thinner evaporates and the oil dries to form a thin, hard, protective and decorative film.

#### Requisites of a good paint
1. Spreads easily and covers the surface well in a few coats.
2. Dries within a reasonable time to a hard, tough, elastic film.
3. The film is smooth, glossy and adheres firmly (no cracking or peeling).
4. Resists weather, water, chemicals and heat.
5. Has a stable, non-fading colour.
6. Non-toxic, has no bad smell, and is economical.

## Check yourself

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

1. What is paint?
   A. A clear solution of resin in volatile solvent with no pigment
   B. A mixture of cement and pigment in water
   C. A solution of bitumen in a solvent
   D. A dispersion of pigment in a drying oil with thinner, drier and additives, forming a protective, decorative film
   Answer: D. Paint is a mechanical dispersion of pigment in a drying oil (vehicle) with thinner, drier and additives; it dries to a thin film. (Key point: Definition of paint)

2. What kind of film should a good paint dry to?
   A. A soft, sticky film
   B. A hard, tough, elastic film
   C. A brittle film that cracks
   D. A porous, water-absorbing film
   Answer: B. A good paint dries in a reasonable time to a hard, tough, elastic film. (Key point: Film property)

3. What happens to the thinner after the paint is applied?
   A. It hardens and forms the film
   B. It reacts with the pigment to form colour
   C. It stays in the film to keep it flexible
   D. It evaporates while the oil dries to a film
   Answer: D. The thinner evaporates and the oil dries to leave the protective film. (Key point: Thinner role)

4. Which of these is also a requisite of a good paint?
   A. Fades in sunlight
   B. Non-toxic and economical
   C. Dissolves in water after drying
   D. Gives a rough finish
   Answer: B. Good paint resists weather, has a stable colour and is non-toxic and economical. (Key point: Other requisites)

## Related in Engineering Chemistry

- [Paint requisites and types of paints](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Apaint-requisites) — Engineering Chemistry, chapter 8
- [Requisites of good paints; varnish](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Apaint-requisites-varnish) — Engineering Chemistry, chapter 8
- [Good paint characteristics; painting galvanized iron](https://www.bctengineer.com/question.md?key=semester_2%2Fengineering_chemistry%3Apaint-galvanized) — Engineering Chemistry, chapter 8, asked 2×

## Related in other subjects

- [Characteristics of a good paint](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Acharacteristics-good-paint) — Civil Engineering Materials, chapter 9
- [Paints, oil paint ingredients, painting woodwork](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Apaints-characteristics-066bh) — Building Technology, chapter 9