SIL-ACT® ATS-42L is a clear penetrating silane with ethylsilicate treatment specially formulated to treat limestone. The treatment causes limestone, concrete, masonry and many natural stones to become repellent to water, chloride and other waterborne contaminants and weathering elements, preventing the premature deterioration of structures and decorative features made from these materials. Performance testing makes SIL-ACT® ATS-42L an excellent choice when you require the highest quality clear water repellent.