Use of one or more polyamines (I) and/or their derivatives for decolorizing and/or for preventing staining of materials containing pyrithione and/or its salts, caused by heavy metal ions, preferably iron-III-ions, is claimed. Independent claims are included for: (1) procedure for decolorizing and/or for preventing staining of materials containing pyrithione and/or its salts, caused by heavy metal ions, preferably iron-III-ions, comprising adding a portion of one or more polyamines and/or their derivatives to the materials, where the materials are oil concentrates, preferably cooling lubricant concentrates, dyes and lacquers, adhesives, sealing agents, leather auxiliary products, paper coating agents and cosmetic agents (2) the materials comprising pyrithione and/or salts and (3) an additive comprising one or more polyamines and/or their derivatives and pyrithione and/or its salts for use in the materials mentioned above.
