Oil- based Polyurethane varnish Old Masters Interior Oil-Based Polyurethane is a clear, self-leveling oil-based finish for interior wood surfaces such as floors, bars, countertops, tabletops, cabinets, wood panels and doors, primed metal and fiberglass. Easy to apply and fast drying, this polyurethane provides long-lasting protection against abrasion, marking, chipping, alcohol and water.