US Patent No. 8,444,716 B1; P&G has patented a soluble solid hair coloring article. It is comprised of direct dye that is comprised of zwitterionic direct dye and one or more soluble porous solids comprising a polymeric structurant, plasticizer, and a surfactant selected from the group consisting of nonionic surfactant, cationic surfactant, anionic surfactant, a mixture of nonionic and cationic surfactant, and a mixture of nonionic and anionic surfactant....