Limestone is a sedimentary rock that consists of calcite and calcium carbonate. The stone primarily consists of skeletal fragments of marine organisms. Other types of limestone is formed by precipitation. Remember in science class – stalagmite/stalactite in caves? Since limestone is a calcite based rock, it is easily susceptible to acids. When an acid comes into contact with a limestone surface, an etch can occur. Depending on type and strength of the acid, results in the amount of damage that can occur. Soy sauce, vinegar, fruit drinks, soda, acne cream, and acid-based cleaning chemicals are a common few that can cause an etch mark. Basically eating away the surface of any calcite based stone. There is no product or sealer on the market today that can prevent an acid etch mark. Etch marks are not stains. Sealers are designed to prevent stains, but can give a little more time (few seconds) before an etch takes effect. Some people think they could can use a topical coating like wax or acrylics to prevent etching. But the acid still etches the topical, if not the stone also. Leaving the same results or uglier. Preventive measures are the best solution. Clean up after spills. Don’t let water stand on the surface. Use a neutral cleaning product for maintenance. But even the unavoidable can happen…. Pictured below is a polished marble floor which sustained etch marks and staining from a pest control chemical. The floors were initially sealed during construction. This helped prevent stains from penetrating deep. But etch marks still ocured.