Stain protection (impregnation) is a preventive treatment that fills the microscopic pores of stone and tile with a water- and oil-repellent substance. Unlike a surface coating, a proper impregnator penetrates into the stone and works from within, leaving the surface texture and appearance unchanged while dramatically reducing the stone's ability to absorb liquids. Impregnating a stone surface is the single most effective thing you can do to protect it.