Solvents and Thinners for Paints and Coatings

The thinner depends on the coating: nitro thinner is used for nitrocellulose coatings and synthetic thinner for synthetic products, while for some paints the manufacturer specifies a dedicated thinner. Using the wrong thinner can cause lumps, dulling or failure to dry. Dose the thinner as stated on the data sheet and mix well before application.

Solvents for epoxy and polyurethane systems dilute the coating and clean tools and surfaces before the product hardens. EPOX solvent is for epoxies and POLY for polyurethanes, and swapping one for the other can compromise the film. Use it immediately after application to clean tools. Work in a ventilated area and wear gloves resistant to solvents.

To remove old paints and enamels use liquid or gel strippers, which act and lift the film. Gels stay on vertical surfaces and detailed areas, while liquids are used on flat, horizontal surfaces. On delicate wood or fine surfaces, choose a neutral stripper, and test first in a hidden spot.

Mineral turpentine and white spirit refer to the same type of petroleum-derived solvent, used to thin oil-based paints, clean brushes and degrease tools. It has a strong odour and is flammable, so do not use it near flames. It is not suitable for water-based paints or epoxy systems. Keep the container closed and dispose of residues according to the safety data sheet.

A slow-evaporating solvent is needed when the paint must level well without brush marks or runs, and in places where odour is a problem. It evaporates more slowly than a standard thinner, so it extends drying times. In hot weather it can help prevent the paint from drying too quickly. Check the data sheet for compatibility with the chosen system.

For spray application the thinner must have a viscosity and evaporation speed suited to the gun and the paint. The manufacturer states the dilution ratio for the chosen gun. A thinner that is too fast causes dust and orange peel, while one that is too slow causes runs. Test on a scrap piece before working the final workpiece.

Solvents and thinners are flammable, and their vapours can irritate the respiratory tract and skin. Work with strong ventilation, away from flames and sparks, and wear solvent-resistant gloves and respiratory protection with a carbon filter. Keep containers closed, in a cool place and in ventilated cabinets. The employer assesses chemical risk and, where explosive atmospheres may form, applies the ATEX rules.