Also known as: French Ultramarine, Ultramarine Green Shade, Ultra Blue
Pigment Blue: 29
Colour Index: 77007
Ultramarine is a deep blue color pigment which was originally made by grinding lapis lazuli into a powder.
This was an extremely expensive pigment until a synthetic ultramarine was invented by French chemist Jean-Baptiste Guimet by heating kaolinite, sodium carbonate and sulfur in a kiln in 1826.
Synthetic Ultramarine is categorised into two families, Ultramarine Red Shade (French Ultramarine) & Ultramarine Green Shade, They can be considered chemically identical because the difference is in the balance of blue S3 and yellow S2 polysulphide chromophores.
The grades of Ultramarine are then micronised, the finer the particles the stronger, greener and brighter the resulting pigment is
Treatment of medium particle size red shade Ultramarine with ammonium chloride converts it to Ultramarine violet. Prolonging the reaction causes the pigment to become redder but weaker. Ultramarine violet is about half the strength of a medium particle size Ultramarine blue
Treatment of Ultramarine violet with HCl gas converts it to Ultramarine pink. This is about half the strength of the violet.
5 Different shades of Ultramarine Pigment we tested, we’ve since tested another 4 more
Ultramarine Green Shade Pigment