Definition - What does Polyurethane Varnish mean?
Polyurethane varnish is an oil-based, water-resistant liquid substance that is used to make surface paints. It is applied as a protective coating to metal surfaces that are prone to corrosion, and to wood and other materials.
Corrosionpedia explains Polyurethane Varnish
Polyurethane varnish is a synthetic material that is formed by a reaction of isocyanate with a polyhydric alcohol. It is highly durable, resistant to heat, chemicals and physical impacts that would otherwise cause wear and tear. The application of polyurethane varnish leaves a shiny, lustrous finish on a material's surface.
For most applications it is used as a protective coating to prolong the life of a surface. However, in some instances it is used purely for aesthetic reasons - such as when painted on wood. Polyurethane varnish improves the look and value of wood that is used to build furniture, art or interior fixtures.