U

Undercoat
Coat applied to the surface after preparation and before the application of a finish coat.

Underfilm corrosion
Corrosion that occurs under films in the form of randomly distributed hairlines.

Use level
Recommended content of a coating additive in a paint formulation expressed in weight percentage per solids of total formulation.

UV-absorber
Compounding material which, through its ability to absorb ultraviolet radiation and render it harmless, retards the deterioration caused by sunlight and other UV light sources. Incorporated into coating, this additive screens the most harmful UV portion of light and thereby protects films and sensitive substrates from the photo-destruction.

UV/EB cured coating
Coating in which the liquid application changes under UV/Electron Beam exposure within seconds into the completely cured film.

UV-curing (extended definition)
Environmentally process using UV light or Electron beam exposure to cure coating films. It converts the incoming radiation energy into a chemical reaction of non-saturated oligomers and/or monomers, in which the photoinitiator plays a key role.

UV/Light stabilizer
Chemical added to paint to absorb the ultraviolet radiation present in sunlight and stabilize organic materials.