The following liquids are commonly used in paints to carry the pigment and binder.

1.      Water.

2.      Aliphatic Hydrocarbon Mixtures (chiefly Paraffins).

3.      Terpenes.

4.      Aromatic Hydrocarbons.

5.      Alcohols.

6.      Esters.

7.      Ketones.

8.      Ethers and Ether-alcohols.

9.      Nitro-paraffins.

10.  Chloro-paraffins.

1.      Water is the main ingredient of the continuous phase of most emulsion paints. It is also used sometimes mixed with alcohols, to dissolve water solube resins. Any type of resin can be made water-soluble. The usual procedure is to incorporate sufficient carboxyl groups into the polymer to give the polymer a high acid value. These groups are the neutralised with a volatile base, such as ammonia or an amine, whereupon the resin becomes a polymeric salt, soluble in water or water alcohol mixture.

If the polymeric part of the salt is negatively charged and can be attracted to a discharge at the anode in an electrolytic cell, anodic electro deposition can occur.

Instead of acidic carboxyl groups on the resin, the resin can be made with basic groups e.g. amines. These can be neutralised with relatively volatile acid to produce a water soluble resin. In this resin system the resin in postively charged and can be discharged at a cathode (cathodic electrodecomposition).

Solution or emulsion paints produced can be applied by virtually any technique. There will be increasing use of this type of paint as legislation, economics and world petroleum shortages encourage the use of decreasing amounts of volatile organic solvents and paints of low flammability.

The chief virtues of water are its availability, cheapness, lack of smell, non-toxicity and non-flammability. However, it is not an ideal paint liquid because of its limited mixibility with other liquids and because the film formers designed to be dissolved or dispersed in it usually remain permanently sensitive to it and evaporation rates are much more difficult to control where fast solvent release rates are required.

2.      Aliphatic hydrocarbons are usually supplied as mixtures, because of the difficulty of separating the individual compouds. A boiling range for the mixture is usually quoted e.g. SBP (Special Blend of Petroleum) Spirit No. 3, 98-122⁰C. Many mixtures contain small amounts of Toluene or Xylene, 15%.

White Spirit is very widely used in alkyd and oil paints, (it’s solvency is not as strong as turps). Some phenols are used as diluents for long oil paints.

3.      Terpenes commonly used nare Turpentine, Di-Pentine and Pine Oil. These are obtained from vegetables, mainly coniferous trees. Turpentine is a clear liquid. It is unsaturated and can therefore be oxidised by the air, this is what makes it a good solvent for oil paints and cetain alkyds. Di-Pentine is a type of turp (mainly Limonene), but evaporates more slowly and has more solvent power, and can be used as a retarder for brushing paints.

4.      Aromatic hydrocarbons are obtained during fractional distillation of crude oil into petroleum products. They are supplied to the paint industry as fairly pure named compounds. Some aromatic mixtures are sold cheaply under proprietary names.

Xylol and toluol are stronger solvents than White Spirit and used for fas t drying, shorter oil alkyds and stoving enamels, also as diluents for NC and TPA.

5-7. Alcohols, esters and ketones are sometimes known as synthetic solvents:       

8. Ethers are not often used for paints, but Ether-alcohols are commonly used.

9-10. Nitro and Chloro Paraffins are not often used in paints because of cost and toxicity, but Trichloroethylene is used for degreasing in many processes prior to painting.