A paint thinner is a solvent used to thin oil-based paints. Solvents labeled "paint thinner" are usually mineral spirits having a flash point at about 40 °C (104 °F), the same as some popular brands of charcoal starter.

Paint Thinner is the most widely used paint solvent for thinning of oil-based paints, varnishes, and enamels. Also effective as a clean-up solvent for brushes, rollers and spray equipment. Can be use to remove dirt and grease from parts and surfaces before painting. Will improve brushing qualities when painting.