DEFINITION: Stain removal is the process of removing a substance or discoloration from natural stone. The method used for stain removal depends on the type of stain and the type of stone surface. For organic stains, a poultice made of an absorbent material and a cleaning agent may be applied to the stain and left to dry, then removed to lift the stain from the stone surface. For oil-based stains, a degreasing agent or solvent may be used to dissolve and remove the stain. For mineral-based stains, an acid-based cleaning solution may be used to dissolve and remove the stain. It is important to use the appropriate techniques and materials for stain removal to avoid causing further damage to the stone surface. Additionally, preventative measures such as sealing and regular cleaning can help to minimize the occurrence of stains on natural stone surfaces.