DEFINITION: Etch refers to a type of damage that can occur on natural stone surfaces when they come into contact with acidic substances. When acidic liquids such as vinegar, lemon juice, or certain cleaning products are spilled or splashed onto natural stone surfaces such as marble, granite, or limestone, they can react with the surface and cause a chemical reaction that eats away at the top layer of the stone. This results in a dull, discolored area on the surface, which is known as an etch mark. Etching is a form of chemical damage that can permanently mar the surface of the stone if left untreated. Etch marks can vary in size and severity depending on the type of stone, the strength of the acid, and the length of time the acid was in contact with the surface