WC-1 is a heavy-bodied, water-based, breathing type mastic, for use as a protective coating over all types of insulation systems, both indoors and outdoors. WC-1 may also be successfully used on masonry surfaces and primed steel when a water-based coating is desired offering durability, weather protection, chemical and oil resistance, and beauty. In most applications, the recommended dried film thickness for WC-1 is 1/16".