Applying the Protective Finish. There are several different types of protective finishes. The most common are penetrating sealers or surface finishes, including polyurethane, varnish, and shellac. They come tinted or clear.
Surface finishes provide a tough, clear coating over stained or sealed wood.
Polyurethane has pretty much replaced varnish, shellac, and lacquer. Often a heavy-traffic wax is applied over the polyurethane. The high gloss shows dust easier. Often the sample stain at the store will give a very different effect when used on your large and particular floor. Be sure whatever type you use is compatible with any undercoat you may have.