OCHRE

Ochre quarry of Rustrel

As a painting pigment it exists in at least four forms:

• Yellow ochre, Fe₂O₃ • H₂O, a hydrated Iron oxide
• Red ochre, Fe₂O₃, chemically identical to yellow ochre, but reddened through heating
• Purple ochre, identical to red ochre chemically but of a different hue caused by different light diffraction properties associated with a greater average particle size
• Brown ochre (Goethite), also partly hydrated iron oxide (rust)

For further information, see the articles on the individual ochres. They are found throughout the world in many shades. Many sources consider the best brown ochre to come from Cyprus, and the best yellow and red ochre from Roussillon, France. All have been used since prehistoric times, and are some of oldest pigments used.

Industry

When the mineral was found in Brixham It became a very important part of the developing Fishing Industry. This gave the old fishing boats their "Red Sails in the Sunset", but the purpose was to protect the canvas from seawater, not to be picturesque. It was boiled in great caldrons, together with tar, tallow and oak bark, the last ingredient giving the name of barking yards to the places where the hot mixture was painted on to the sails, which were then hung up to dry.

The ochre was also used to make a very special paint. This was invented in Brixham in about 1845 and was the first substance in the world that would stop cast iron from rusting. None of the well-known scientists of the day could find a way of doing this, and, when the paint began to be made here, it sold all round the globe.

See also

• Clay earth pigment
• List of colors

External links

• Red Ochre, Yellow ochre, and Brown ochre, from Pigments through the ages

References

• Fuller, Carl; Natural Colored Iron Oxide Pigments, pp. 281-6. In: Pigment Handbook, 2nd Edition. Lewis, P. (ed.). New York: John Wiley & Sons, 1988.
• Thomas, Anne Wall. Colors From the Earth, New York: Van Nostrand Reinhold, 1980.