Unlike lacquer, shellac and varnish, which have been around for centuries, polyurethane is a product of 20th-century lab ...

This is done by evenly sanding and cleaning the floor to remove any debris or old finish. It makes it easier for the polyurethane to stick and can prevent a bumpy or uneven application.

Finish your woodworking project or furniture refinishing job with an oil-based polyurethane ... by wet-sanding with 400-grit sandpaper mounted to a sanding block. Dip the sandpaper in water ...