Deep into the yellow

 
Global use of lead chromates has significantly declined in recent years due to the toxicity of the pigments. In the past decade alone, the quantity used has declined by more than half, down from 90,000 t in 2000 [1]. However, due to the excellent price/performance ratio of lead chromates and the partial use of the pigments in color mixing systems, complete replacement has failed to occur so far. The upcoming approval requirement according to REACH annex XIV in May of 2015 is increasing the focus on the issue of alternative formulation concepts again. Lead chromates are typically used to achieve good hiding power with a high brilliance level of the paint film. In fact, so far there is no individual pigment alternative for an exact 1:1 replacement of specific chrome yellow P.Y. 34 or molybdate red P.R. 104 pigments. The reformulation of such a formula is still a challenge even for application technicians with coloristic experience. Formulation of colors using multiple pigments is the current state of the art. Pigment combinations, hybrid pigments, and customized pigment preparations are already being used successfully as alternatives to lead chromates. Classic pigments for such combinations include P.Y. 74, P.Y. 83, P.Y. 139, P.Y. 151, P.Y. 154, P.R. 112, and P.R. 254 as organic components, and P.W. 6, P.Y. 53, P.Br. 24, and P.Y. 184 as inorganic components. In these combinations, the inorganic component contributes to achieving the hiding power, while the organic component is used to adjust the hue angle, chroma, and color strength.