1-6 BASIC KNOWLEDGE ABOUT PAINTS AND PAINTING 3. SOLVENTS AND THINNERS Solvent is a liquid that dissolves another substance to form a solution. In the process of making paints, a solvent is used to dissolve resins so that pigments are mixed easily with the resins. Generally, solvent is pre-mixed in paints in cans. A thinner is a mixture of solvents. It is used to dilute paints to an appropriate viscosity level for applica- tion. Solvents and thinners evaporate as the paint is dried, and do not remain in the coating. ----- .,.,...,.,.,...--- -- -- -- ~::-=-=----- ---- DILUTION OF PAINTS BY A THINNER The table below lists various types of solvents that are commonly used in paints.
Various types of resins are used in paints, and they cannot all be dissolved by a single solvent. A thinner having only a small dissolving power cannot dissolve resins adequately. If a thinner has a very strong dis- solving power, it will affect the coat during repainting and cause bleeding. In consideration of all those problems, a special thinner made up of several types of solvents is desig- nated for exclusive use with each paint. In addition, solvent types and compositions are varied by season so that the user can select thinners having the most appropriate evaporating speed. -8- Type Solvent name Alcohols Methyl alcohol, ethyl alcohol, isopropyl alcohol, isobutanol, etc.
Esters Methyl acetate, ethyl acetate, butyl acetate, isopropyl acetate, etc. Ethers Ethyl cellosolve, butyl cellosolve, etc. Ketones Acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, etc. Hydrocarbons Aromatics Benzole, toluole, xylole, etc. Aliphatics Petroleum ether, petroleum benzine, gasoline, etc.