U.S. Patent No. 7,429,275 B2 L’Oréal S.A. has patented a method of dying human keratin materials that involves application of at least one direct dye comprising at least one non-metallic or metallic cationic compound chosen from porphyrin compounds and phthalocyanin compounds, wherein the metal element is at least one metal or metal ion chosen from columns IA and IIA of the Periodic Table of the Elements, zinc, and silicon....