Easily patch, repair and skimcoat indoor surfaces with the Henry 547 UniPro. Universal Patch and Skimcoat. This underlayment sets in 2 hours and can be used on concrete, wood and metal flooring as a feather-edge, deep fill or embossing leveler. For patching and repairing indoor surfaces prior to flooring installation.Non-shrinking reduces install time and a high compressive strength of over 5,000 lbs PSI will make this a a very durable product. Install over: Concrete, wood substrates, steel, stainless steel, brass, lead, ceramic, terrazzo, marble, existing “cutback” residue and existing resilient (as an embossing leveler). The non-sanded formula trowels easily for a smooth finish. Sold in a 25 lbs bag.