A stone sealer is a clear or colored liquid that is applied to stone surfaces in order to protect them from staining and weathering. The sealer penetrates into the stone, forming a durable barrier that repels water and oil-based stains. Stone sealers are available in water-based and solvent-based formulations, and they can be applied to a variety of stone surfaces, including marble, granite, limestone, and slate. In addition to repelling stains, stone sealers also help to resist degradation from ultraviolet light and freeze-thaw cycles. As a result, they can extend the life of stone surfaces and help them to retain their natural beauty.