Cobalt blue

Cobalt is a cool, slightly desaturated blue colour, historically made using cobalt salts. It was discovered by Louis-Jacques Thenard in 1802^{[citation needed]}. The world leading manufacturer of cobalt blue in the 19th century was Blaafarveværket in Norway, led by Benjamin Wegner. It is extraordinarily stable. Chemically it is a cobalt(II) oxide-aluminium oxide, or cobalt(II) aluminate, CoAl₂O₄. Commercial production began in France in 1807. It is made by sintering the stoichiometric mixture of finely ground CoO and Al₂O₃ at 1200°C.

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The first recorded use of cobalt blue as a color name in English was in 1777. ^[1]

Cobalt blue in human culture

Art

• John Varley suggested cobalt blue as a good substitution for ultramarine blue for painting skies.
• Maxfield Parrish, famous partly for the intensity of his skyscapes, used cobalt blue, and cobalt blue is sometimes called Parrish blue as a result.

Construction

• Because of its chemical stability in the presence of alkali, cobalt blue is used as a pigment in blue concrete.

Glassmaking

• The blue seen on many glassware pieces is cobalt blue, and it is used widely by artists in many other fields.

Ophthalmology

• "Cobalt Blue" is used a filter used in ophthalmoscopes, and is used to illuminate the cornea of the eye following application of fluorescein dye which is used to detect corneal ulcers and scratches.

References

1. ^ Maerz and Paul A Dictionary of Color New York:1930 McGraw-Hill Page 91; Color Sample of Cobalt Blue: Page 131 Plate 34 Color Sample L7

See also

• List of colours