A bis(azo) compound that consists of a benzene core having two (4-amino-6-chloro-1,3,5-triazin-2-yl)amino groups attached at positions 1 and 4 and which in turn have 5-hydroxy-6-[(2-sulfophenyl)diazenyl]-2,7-disulfonaphthalen-4-yl groups attached to their 4-amino functions.