This article discusses the theory of photoinitiation of UV cured coatings and how through judicious selection of photoinitiators and amines the post cure discoloration of thin, clear UV cured films can be minimized. The results of a study involving combinations of six photoinitiators and three amines in both epoxy and urethane acrylate resin systems are presented. Mechanisms of discoloration for two of the photoinitiators are also shown. Values for the wavelengths of maximum absorption in methanol and hexane, as well as corresponding molar absorptivities are given for each photoinitiator.