Cobalt Blue usage dates back more than 3, years for the coloring of blue glass but the source of the color was not understood and so its use tended to be sporadic and accidental. It occurs in association with copper and nickel ores and wherever it occurs arsenic is always present. During the Middle Ages when Egyptian blue ceased production and the manufacturing methods had been forgotten, alchemists developed the pigment called smalt which was superficially similar to Egyptian Blue in that it was a dark blue glass that was ground up.
Composition and Properties of Cobalt Blue
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Cobalt blue is lighter and less intense than the iron-cyanide based pigment Prussian blue. It is extremely stable and historically, has been used as a coloring agent in ceramics especially Chinese porcelain , jewelry, and paint. Transparent glasses are tinted with the silica-based cobalt pigment smalt.
Brief description of Cobalt blue:
It's a cobalt oxide-aluminum oxide. It is now the most important of the cobalt pigments. Although smalt, a pigment made from cobalt blue glass has been known at least since the Middle Ages, the cobalt blue established in the nineteenth century was a greatly improved one.
Cobalt blue is a clean blue that is neither warm nor cold. With a moderate tinting strength, it is useful on the palette for muted colour mixes. Cobalt blue deep, a unique, red shade cobalt blue is made by using cobalt zinc silicate. Until the 19th century the best blue pigment available to artists was ultramarine. Laboriously ground from lapis lazuli, a semi-precious stone mined only in distant Afghanistan, the prohibitive cost of this pigment prompted the Napoleonic administration to find an alternative. With a purer tint than Prussian blue, it was immediately taken up by artists. In fact, cobalt blue sometimes is called Parrish blue, after the artist Maxfield Parrish, who made famously intense blue skyscapes using this colour.