Ultraviolet Absorber
A substance used in some exterior coating that absorbs UV radiation, and reduces or delays damaging UV effects from sunshine to the coating or substrate.
Ultraviolet Radiation (UV)
The portion of the radiant energy of the sun’s spectrum that causes damage to coatings and sealants and to the surface of unprotected wood.
Ultraviolet Resistance
The ability of a coating or sealant to remain undamaged when subjected to UV radiation, as from direct sunlight.
Undercoat
A coating, generally pigmented, that provides improved adhesion and/or maximized gloss and uniformity of a finish coat when used on bare wood.
Undertone
A subtle or subdued color of limited intensity that lends character to the dominant color of a coating.
Urethane
A type of binder used in coatings. Characterized by excellent flexibility and chemical resistance.
Urethane-Modified Alkyd
An alkyd that has been chemically modified for improved flexibility and chemical resistance. A binder used in “polyurethane” varnishes.
U.S. Gallon
A unit of volume equal to four liquid quarts, eight liquid pints, 231 cubic inches, or 3.785 liters. A U.S. gallon of water weighs 8.33 pounds (3.78 kg).