The MoistureBloc Vapor Reduction System from Vexcon consists of a primer and top coat that can be applied on concrete floors or slabs on grade to block the transmission of water vapor, which may damage tile adhesives and cause other problems. Each coat dries overnight. The system is designed to withstand 576 psi (4 Mpa) of hydrostatic water pressure, and costs the contractor approximately 30 cents per square foot. Contact Vexcon directly at (888) 839-2661 or www.vexcon.com.