History of Cobalt violet:
The remarkable range of pigments that could be produced with cobalt included cobalt violet, is known since 1859. Salvetat first described the preparation of cobalt violet in Comptes Rendus des Seances de l'Academie des Sciences XLVIII in an article titled, "Matieres minerales colorantes vertes et violettes." The dark variety is anhydrous cobalt phosphate which was made by mixing soluble cobalt salt with disodium phosphate. It was washed and then heated at a high temperature. The light variety, developed in Germany in the early nineteenth century, is anhydrous cobalt arsenate. The light variety was particularly poisonous because of its arsenic content.
Both of the cobalt violets were considered to be very permanent but the light variety could change in oil due to the yellowing of linseed oil. They were both compatible with all painting media. Their transparency, weak tinting strength and high cost limited their use but their fastness to light made them more desirable than the older organic dye violets.
When was Cobalt violet used?
| Discovery | Used until |
|---|---|
| 1859 | continues in use |