Of all the blue pigments, cobalt blue is the only one with a good opacity. He became a baron (1825), a member of the. His independent achievements included studies of esters (1807), the discovery of hydrogen peroxide (1818), and work in organophosphorus compounds. He did much notable research with his friend Joseph-Louis Gay-Lussac. Depending on the colour, the price can exceed 300 euros per kilo. In 1799 he discovered Thenard’s blue, a pigment used in the colouring of porcelain. The other colours are still used today and are known for their excellent lightfastness.Ĭobalt pigments are exceptionally lightfast, but also extremely expensive. ![]() The red and yellow have meanwhile been replaced by the more stable cadmium pigments. In the course of the nineteenth century the green-like Cerulean blue, cobalt violet, red cobalt and cobalt yellow were developed, with tin oxide, phosphate, magnesium oxide and potassium oxide, respectively. At the end of the eighteenth century, for example, in combination with zinc oxide, cobalt green was discovered. Later on, other colours based on cobalt were discovered as well. He discovered that a combination of cobalt oxide and aluminium oxide resulted in a highly stable blue pigment, the current cobalt blue. It was the French chemist Louis Jaques Thénard who in 1802 started to experiment with a cobalt-arsenic compound which was used in Sèvres porcelain. The big disadvantage, however, was that if too much oil was added the colour blue would eventually change to a dirty grey-green. With a moderate tinting strength, it is useful on the palette for muted colour mixes. For a long time this cobalt blue served as an affordable alternative for ultramarine which was made from the Afghan semi-precious stone lapis lazuli, as this was difficult to obtain and was very expensive. Cobalt blue is a clean blue that is neither warm nor cold. The glass was ground and then mixed with a binder. A well-known blue-coloured glass is smalt, which has been used as a raw material for paint since the middle ages. Cobalt compounds attract arsenic, which when heated is released as extremely toxic arsenic trioxide.īack in ancient times various tinted minerals containing cobalt were used to colour glass and ceramics. We now know that there is a totally different explanation. The ‘miners’ thought that this was the work of kobolds, who stole the silver and replaced it with a toxic metal or kobold. It has been widely used since the early 1800s, following its discovery by the French chemist Thenard at the beginning of the century. ![]() ![]() Because when ‘fake silver’ was melted down, toxic substances were often released, which were lethal when inhaled. However, there are other types of metal that look like silver and frequently they were mistaken as such, with some unpleasant consequences. It is easy to melt and, what’s more, has a beautiful sheen. In the search for useful metals and stones, man discovered silver. Cobalt Blue: from ‘fake silver’ to colourful pigment average tinting strength Excellent lightfastness Other name used for this colour is Thenards blue Health and safety information for Cobalt pigments.
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