Cadmium colors

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Cadmium orange pigment

Cadmium paint is a collective name for yellow , orange to red pigments . Cadmium yellow used to consist of cadmium sulfide . The modern cadmium pigments developed by industry consist of mixed crystals with varying proportions of cadmium or zinc with sulfur or selenium. Cadmium yellow is a cadmium zinc sulfide (Cd, Zn) S, cadmium red is a cadmium sulfoselenide Cd (S, Se). Cadmium pigments may not be used for painting and building purposes. The coloring of plastics with cadmium pigments is also prohibited. They are allowed as artist paints or for restoring paintings.

Today's cadmium pigments are not classified as hazardous substances according to the GHS system of the EU. They have a significantly lower toxic potential than other cadmium compounds. They are not soluble in water and are very chemically stable. When heated or burned, they release the highly toxic cadmium oxide . Leftovers must be disposed of as hazardous waste, because cadmium compounds are generally not allowed to get into the environment.

Cadmium pigments are strongly colored , very lightfast and weatherproof . In particular, they are thermally stable (heat-resistant) and resistant to reducing agents . Organic pigments such as diketopyrrolopyrrole pigments are not a substitute for water-based artist paints, as these are difficult to wet with water.

Although greenockite (cadmium blende, CdS) is a natural mineral, its use as a painting medium has not been proven. After Friedrich Stromeyer discovered cadmium yellow in 1818, cadmium paints were not produced until the 1920s (Bayer 1925). They served as a substitute for the toxic chrome yellow (lead (II) chromate PbCrO 4 ) and its derivative chrome red , but also for cinnabar ( cinnabarite ).

Individual evidence

  1. ↑ Cadmium pigments in Seilnacht's Lexicon of Dyes and Pigments
  2. ↑ Entry on cadmium sulfoselenide in the GESTIS substance database of the IFA , accessed on August 21, 2017(JavaScript required) .

Literature sources