Reports investigations on the rate of gelation of epoxy resin solutions under the action of ethyl diamine (EDA) and adducts of ethylene diamine and triethylene tetramine with epoxy resins (EDA/Ep) and (TECZA/Ep). The distribution of epoxy resins in the stone structure has been given, as well as the influence of the conditions of impregnation and drying on the color and light resistance of epoxy impregnated stone. Pinczów porous limestone and Nietulisko sandstone were used, with water absorption values of ca. 18% and 12% respectively. As impregnants, solutions of Polish-made epoxy resins Epidian 1 and Epidian 5 were applied. The experiments are discussed and permit the conclusion that the light resistance of stone treated with epoxy resins depends on the method of impregnation. To obtain satisfactory results, resin should be removed from the surface and hindered from migration to the surface before being completely hardened. Impregnation through a layer of lignin, washing off the surface with solvents, and weathering the impregnated stone in an atmosphere of white spirit will prevent any change of aspect under the action of light. Light resistance can also be achieved by application of light-resistant solutions of thermoplastic resins of organosilicon products to the surface of stone after the impregnation with epoxy. Polyamide hardeners are decisive for stone light resistance. The best results were obtained for an adduct of ethylene diamine with Epidian 5. Pure triethylene tetramine should be avoided.