The invention relates to novel dyes of the formula (1) in which D represents a phenyl or naphthalene residue which is substituted by one or two sulphonic Acid or carboxylic acid groups and, optionally, by one or two groups selected from C.sub.1-C.sub.4alkyl, hydroxyl and nitro, each R.sub.1 and R.sub.2, independently, represent hydrogen or, a C.sub.1-C.sub.4alkyl group, R'.sub.1 represents hydrogen, hydroxyl, C.sub.1-C.sub.4alkyl or C.sub.1-C.sub.4hydroxyalkyl, R.sub.3 represents hydrogen, C.sub.1-C.sub.4alkyl or phenyl, which is unsubstituted or substituted by one or two groups selected from C.sub.1-C.sub.4alkyl, C.sub.1-C.sub.4alkoxy, halogen, hydroxyl, --NH.sub.2, nitro, --SO.sub.3M and --CO.sub.2M and M represents hydrogen, an alkaline or alkaline earth metal, ammonium or ammonium that is mono-, di-, tri- or tetrasubstituted by C.sub.1-C.sub.4alkyl or C.sub.2-C.sub.4hydroxyalkyl or a polyglycolammonium cation and also known dyes of formula (5), in which D' represents a phenyl or naphthalene residue which is substituted by one or two sulphonic acid or carboxylic acid groups and, optionally, by one or two groups selected from C.sub.1-C.sub.4alkyl and C.sub.1-C.sub.4alkoxy and R.sub.3 and M are as defined above, and their mixtures suitable for shading white paper, a process for shading, a process for the preparation of the novel dyes and white paper which has been treated with such shading components.