Thinner is a volatile solvent used to dilute oil-based paints, improve their flow, and clean application tools. It lowers the paint's viscosity so it spreads smoothly and can be used in sprayers, and it is also highly effective at stripping wet paint off brushes and rollers.A breakdown of what thinners do and how they are used includes:Diluting Paint: Restores thickened paint to its proper, brushable consistency.Improving Application: Helps paint flow more evenly, reducing brush marks and creating a professional finish