A diazotype material of high light fastness is to be provided, which can be used as one-component material or two-component material. Easily accessible additives are therefore to be developed, which effect an increased light fastness of the dye formed as compared with the hitherto known variants. This object is achieved by the use of substituted piperazines of the general formula <IMAGE> as bleaching inhibitors. The meaning of the symbols R1 and R2 is given in Claim 1. These have an increased effectiveness, without deterioration of the sensitometric properties of the material.
