R-Guard GypPrime seals the cut edges of gypsum wall boards exposed in rough openings for windows and doors. The sealed edge makes a perfect surface for easy application of R-Guard Joint & Seam Filler or R-Guard FastFlash®. GypPrime brushes on easily and efficiently, and its glue-like viscosity reduces rundown and potential for spills. GypPrime usually dries in less than 30 minutes. Use R-Guard GypPrime as part of a continuous building-wide air barrier system, or to complement conventional waterproofing or air barrier components.