Grey Patch™ is a polymer-modified, calcium-aluminate, rapid-setting, interior patching compound used to fill voids and smooth the surfaces of open concrete and approved wood underlayments and may be used without a primer or additive. Common floor coverings such as VCT and carpet can be installed in as little as 1 hour. When used in the “skim-bond system,” Grey Patch™ can be used on cutback and non-water-soluble adhesive residue, singlelayer, fully-bonded VCT and other non-porous surfaces.