1. PAINTS AND CLEAR FINISHES Paints and clear finishes are thin coatings applied to surfaces in liquid form, which gradually dry to become flexible solids.

2. Paints and clear finishes are used for such purposes as: a- Protection of a surface from the effects of abrasion, sunlight, dampness, dust, etc. b- Contributing to the cleanliness of a building, by providing surfaces with a finish which is easily cleaned. c- Contributing to the appearance of an interior by introduction of colours, lightness or darkness, and a reflective or matt surfaces. d- Identification of pipelines.

3. COMPOSITION OF PAINTS AND CLEAR FINISHES Clear finishes (varnishes) are transparent, and are used protect and enhance the appearance of natural, or applied surface materials. A clear finish is composed of a binder, solvent and additives. Paints are composed of similar components, but also required pigments and extenders to provide colour and opacity.

4. BINDERS ( also known as ‘film formers’ or ‘mediums’) The functions of binders are: To bind together the constituents of the paint or clear finish; To convert the liquid coating into a solid film; To provide the liquid with adhesive properties; To influence the degree of sheen; To provide paints with water resistant properties.

5. Binders today are based on either: Drying oils such as linseed oil, soya-bean oil or tung oil; Natural resins, which are either extracted from living trees or the fossilised remains of trees; Oleo-resins which are a combination of oil and resins; Synthetic resins (which are very widely used today) and of which polyurethane resin, polyvinyl acetate (p.v.a) resin, acrylic emulsions and phenolic resins are examples.

6. SOLVENTS (or Thinners) Solvents are colourless liquids which are incorporated in the paint or clear finish, and act on the binder to thin the quality of the paint. This both improves the ease of application and increases the penetration of the paint or clear finish. The solvent evaporates during the drying-out process.

7. Examples of solvents include: White spirit, which is commonly used with oil and oleo-resin paints; Ethers, which are used with cellulose resins and synthetic finishes; Water, which is used with cement and emulsion paints.

8. ADDITIVES Most paints and clear finishes contain one or more additives. Some of the additives used are: A) Driers and hardeners: driers are added to paints which have a drying oil binder, in order to speed up the drying process. Hardeners (or ‘catalysts’) are added to paints with certain synthetic resin binders. They cause a chemical change which converts the synthetic resin into a hard film.

9. A) Flatting agents, which reduce the gloss of the dried film of paint. B) Anti-skinning agents, which prevent formation of the skin which sometimes occurs in tins of oil-based paints. C) Thixotropic agents, which provide the paint with a gel quality. Such paints require no stirring, and drip less than other paints.

10. PIGMENTS Pigments are fine powdered materials which provide colour and opacity in paints, and may contribute to the durability of the paint. Pigments are derived from sources such as:  Chemically treated metals, for example titanium dioxide which is white, and is used for interior paints, or iron oxide which is yellow or red and used in of finishing paints;  Coloured earths, for example yellow ochre or burnt umber which are used for all paints;  Treated chemical compounds, for example Prussian blue, which is used for oil/alkyd paints.

11. EXTENDERS Extenders are finely ground natural materials (mostly natural earths) which have no effect on the colour of paints, but may adjust certain of properties of the paint. Extenders may, for example:  Improve the ease of application of the paint;  Improve the adhesion of the paint to undercoats;  Give body to the paint;  Increase the hardness of the paint film.

12. PAINT SYSTEMS Surfaces are usually painted with several coats of paints, each coat performing a specific function. A series of coats of paints is known as a “paint system”. A typical paint system will comprise of:  Primer;  Undercoat(s)  Finishing coat(s).