Synonyms: 2-Naphthalenesulfonicacid,6-[(2,4-diaminophenyl)azo]-3-[[4-[(2,4-diaminophenyl)azo]phenyl]azo]-4-hydroxy-,monosodium salt (9CI); 2-Naphthalenesulfonic acid,6-[(2,4-diaminophenyl)azo]-3-[[p-[(2,4-diaminophenyl)azo]phenyl]azo]-4-hydroxy-,sodium salt (8CI); C.I. 31535; Styx Black