Described are imbibition compositions that incorporate kinetic enhancing
additive(s) into photochromic polymeric host material. Kinetic enhancing
additives include organic polyol(s), epoxy-containing compound(s) or a
mixture thereof that improves the performance of organic photochromic
compounds in the polymeric host as determined in the Photochromic
Performance Test. Also described is a process for incorporating kinetic
enhancing additives into polymeric substrates prior to, after and/or with
organic photochromic compounds and the resulting photochromic articles
produced by such a process.