- 2066 Bhadra (old course) · 16 marks
Paints, oil paint ingredients, painting woodwork
Short answer
Paint is a liquid that dries to a protective film. Oil paint contains base, linseed oil vehicle, pigments, driers, thinner, extenders. Good paint is easy to apply, opaque, durable, glossy, washable. New wood painting: sand, knot, prime, putty, undercoat, finish. Old wood: scrape, sand, fill, spot prime, then undercoat and finish.
Define paints. What are the ingredients of oil paints? What are the characteristics of good paints? How do you undertake painting works in new and old woodwork?
Paints
Paint is a liquid mixture of pigment in a vehicle which, when applied on a surface and dried, forms a thin protective, decorative film. It protects against weather, moisture, rust and rot, and improves appearance.
Ingredients of oil paint
| Ingredient | Example | Function |
|---|---|---|
| Base | White lead, zinc white, titanium dioxide, red oxide | Gives body, opacity and covering power |
| Vehicle (carrier) | Linseed oil, tung oil, poppy-seed oil | Carries the pigment, spreads and dries to a hard film |
| Pigment | Iron oxide (red), chrome (yellow), carbon black, ultramarine | Gives colour |
| Drier | Litharge, red lead, manganese salts | Speeds up drying of oil |
| Thinner (solvent) | Turpentine, mineral spirit | Makes paint workable, evaporates after application |
| Extender (adulterant) | Barytes, gypsum, china clay | Adds bulk, reduces cost |
Characteristics of a good paint
- Easily applied, spreads evenly with a brush.
- Good covering power (opacity) with fewer coats.
- Dries in a reasonable time into a hard, smooth, glossy film.
- Durable, resists weather, heat and abrasion.
- Does not crack, peel, blister or fade.
- Washable, non-toxic and fire-retardant.
- Gives good colour and is economical.
Painting on new and old woodwork
New woodwork:
- Rub the surface with sand paper; seal knots with knotting (shellac) solution.
- Apply a priming coat (red lead with linseed oil); allow 24 hours.
- Fill holes and cracks with putty; sand smooth.
- Apply one or two undercoats, each sandpapered after drying.
- Apply one or two finishing coats of the final colour.
Old woodwork:
- Remove old peeling paint by scraping, a blow lamp or paint remover; wash and dry.
- Rub down with sand paper and fill defects with putty.
- Spot prime bare areas.
- Apply undercoat then finishing coats as for new work.
✓ Answer checked by Claude Opus 5.5 (high effort)
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