The Retro-Coat™ Vapor Intrusion Coating System is a complete product line that consists of chemically resistant materials to properly protect existing structures from the threat of contaminant vapor intrusion. This animation shows the install steps. Retro-Coat Gel and fillers are used to repair concrete cracks and other imperfections. Retro-Coat PRIMER is then applied to the concrete surface as final preparation. This increases adhesion between the concrete slab and the Retro-Coat and addresses moisture vapor transmission. Finally, Retro-Coat is applied to a nominal thickness of 20 dry mils.