Cadmium yellow/red

/ kad • mee • uhm   are • inj /

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How Cadmium yellow/red is made:

Origin: artificial Minerals: greenockite and hawleyite (at Mineralogy Database). Those natural minerals though known in nature were not used for pigments.
 
greenockite (CdS)
Artificial variety of pigment Precipitation of a solution of cadmium(II)-nitrate with a solution of sodium sulfide.
In the lab
Materials needed: Cadmium(II)-nitrate (Cd(NO3)2 · 4 H2O), Sodium sulfide (Na2S · 9 H2O)
Safety (MSDSs): Cadmium(II)-nitrate, Sodium sulfide (at Fisher Scientific)
Method: Solution of 9,7 g Cd(NO3)2 · 4 H2O in 50 ml deionized water is added slowly to a stirred solution of 8,3 g Na2S · 9 H2O in 50 ml deionized water. The resulting precipitate is filtered, dried and homogenized in a mortar.

Illustration of the process:

Solutions of cadmium(II) nitrate and sodium sulfide
heating the solutions precipitation reaction
Solutions of cadmium(II) nitrate and sodium sulfide
heating the solutions
precipitation reaction
stirring the precipitate
Filtration of the product
stirring the precipitate
Filtration of the product

The ground pigment:

Pile of ground Cadmium yellow/red

Other browns
(intro) - Umber - Van Dyke brown

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