USG First Coat Sheetrock Primer 5 GALLON 544822048USG First Coat Sheetrock Primer is a 5 gallon primer sealer designed to prepare surfaces like gypsum panel face paper, concrete, and finished joint compound by equalizing porosity and surface texture differences. It is intended as a base coat and must be covered with a final paint layer. This product is not recommended for use over new plaster finishes. Ideal for professional applications, it ensures a uniform surface for optimal topcoat adhesion.