Last reviewed 16 Sept 2026 · 10 min read
Purposes of painting
- Protection of surfaces against weathering, moisture, corrosion (metals), decay and insects (timber) and chemical attack.
- Decoration — colour, texture and attractive finish.
- Hygiene — smooth, washable surfaces (hospitals, kitchens).
- Special functions — heat reflection, fire retardancy, luminous or road marking, anti-fungal, waterproofing.
Constituents of paint
| Constituent | Function | Examples |
|---|---|---|
| Base (principal pigment) | Gives opacity (hiding power), body and durability; forms the bulk of the solid film | Titanium dioxide (most widely used white), zinc oxide (zinc white), lithopone, white lead (toxic — largely discontinued), red lead and red oxide (primers for iron and steel) |
| Vehicle (binder, medium) | Liquid that binds pigment particles into a film and makes the paint adhere to the surface; forms the film on drying | Linseed oil (raw or boiled), tung oil, poppy oil; synthetic resins — alkyd, acrylic, epoxy, polyurethane, vinyl; latex emulsions |
| Pigments (colouring) | Impart colour; some improve protection | Iron oxides (red, yellow, brown), carbon black, chrome yellow, ultramarine blue, phthalocyanine blues and greens, zinc chromate (anti-corrosive) |
| Driers | Accelerate drying (oxidation and polymerisation) of drying oils | Litharge (lead monoxide), manganese dioxide, cobalt and zirconium compounds (octoates, naphthenates), lead acetate |
| Thinners (solvents) | Reduce viscosity for easy application; evaporate after application | Turpentine, mineral turpentine (white spirit), naphtha, xylene; water for water-based paints |
| Extenders (inert fillers) | Reduce cost, adjust consistency, reduce shrinkage and cracking, improve film properties | Barytes, chalk (calcium carbonate), gypsum, silica, china clay, talc, mica |
| Additives | Special properties | Anti-settling agents, fungicides, anti-skinning agents, dispersants, UV absorbers |
Pigment volume concentration (PVC):
Low PVC gives glossy, durable, less porous films (enamels); high PVC gives flat (matt) films with lower washability (distempers, flat wall paints).
Characteristics of a good paint
Good hiding (covering) power and spreading; easy application with a brush or roller; quick drying without cracking; forms a hard, durable, elastic film; good adhesion; resistance to weathering, moisture, chemicals and UV (colour fastness); smooth, uniform finish; washable (where required); non-toxic and low-VOC; economical.
Types of paints
| Paint | Composition / features | Uses |
|---|---|---|
| Oil paint | Pigments in drying oil (linseed) with driers and thinners; durable, good gloss; slow drying, odour | Wood, metal, walls (traditional) |
| Enamel paint | Pigments in varnish or alkyd resin; hard, glossy, smooth, washable, resists water and chemicals | Doors, windows, metal work, furniture, kitchens and bathrooms |
| Synthetic (alkyd) enamels | Alkyd resin base; quick drying, glossy, durable | Metal and wood surfaces |
| Emulsion paint (plastic/acrylic) | Pigments and polymer latex (acrylic, PVA) dispersed in water; quick drying, little odour, washable, breathable, easy to apply | Interior and exterior walls, plastered and concrete surfaces |
| Distemper | Whiting (chalk) with glue/casein and pigments in water — dry distemper (powder) or oil-bound distemper (with emulsified oil); cheap, flat finish; not very washable (oil-bound slightly washable) | Interior plastered walls and ceilings (economical) |
| Cement paint | White cement, pigments, accelerators and water repellents in powder form, mixed with water; applied on wetted surfaces and cured | External masonry and plaster, rough concrete surfaces |
| Aluminium paint | Aluminium powder/flakes in spirit or oil varnish; reflects heat and light, protects against corrosion | Water tanks, steel structures, roofs, pipes, gas tanks |
| Anti-corrosive paints and primers | Red oxide, zinc chromate, zinc phosphate, zinc-rich (galvanic protection) | Primers for iron and steel |
| Bituminous paint | Bitumen dissolved in solvent — black, waterproof, acid resistant | Iron and steel underwater, pipes, damp-proofing, tanks |
| Epoxy paints | Two-component epoxy resin and hardener — very hard, chemical and abrasion resistant; poor UV resistance (chalking) | Industrial floors, chemical plants, marine structures, pipes |
| Polyurethane paints | Tough, glossy, abrasion and weather resistant | Floors, wood finishes, exterior coatings |
| Fire-retardant / intumescent paints | Swell (intumesce) on heating to form an insulating char | Steel structures, timber — fire protection |
| Other types | Luminous paint, heat-resistant (silicone) paints, road-marking (thermoplastic) paints, anti-fungal paints, textured paints, rubber-based paints, graphite paints | Special applications |