A mixture of platelet-shaped, copper-containing metallic effect pigments having a copper content of 60% to 100% by weight, based on the total metal content, with at least one further component, where the copper-containing metallic effect pigments have a thickness distribution, determined via thickness counting by scanning electron microscopy (SEM) and represented as cumulative undersize distribution, a) with an h50 of 10 to 100 nm, and b) with an h90 of 20 to 150 nm, and in that the at least one further component is a cellulose derivative selected from the group consisting of alkylcellulose, hydroxyalkylcellulose, alkyl(hydroxyalkyl)cellulose, and mixtures thereof, and/or is at least one additive having antioxidative and/or radical-inhibiting properties. The disclosure further relates to a method for producing this mixture, and to a coating composition.