Yellow ochre
Composition and Properties of Yellow Ochre
The main color giving component of natural yellow ochre (ocher, yellow earth) is limonite which is not a single mineral but a mixture of several iron-containing minerals among them goethite, akageneite, lepidocrocite, and jarosite, goethite (iron oxide hydroxide α-FeOOH) being the main component.Iron oxides are stable at high temperatures but not resistant against acids. The pigment is absolutely stable as is documented by the cave paintings still in excellent condition after many thousands of years. It is compatible with all other pigments and is often used in mixture with other paints.
Names of Yellow Ochre
Yellow earthPY 43, CI 77492From Old French ocre (c.1300) and directly from Late Latin ocra, from Latin ochra, from Greek ochra, from ochros “pale yellow,” of unknown origin.From Online Etymology Dictionary
Preparation of Yellow Ochre
The natural mineral is washed in order to separate it from sand and other impurities. The resulting sludge is dried and the pigment is ground and sieved.Ochre in Rustrel, FranceYellow ochres can also be prepared artificially by a variety of procedures. There are two main types of production methods: precipitation of iron oxides and/or hydroxides from solutions of iron salts is one possibility (2,3), thermal decomposition of iron compounds the other.
History of Use
Yellow ochre has been in use since prehistoric times until the present day. The following graph gives the frequency of its use in the paintings of the Schack Collection in the Bavarian State Art Collections in Munich (1).References(1) Kühn, H., Die Pigmente in den Gemälden der Schack-Galerie, in: Bayerische Staatsgemäldesammlungen (Ed.) Schack-Galerie (Gemäldekataloge Bd. II), München 1969.Examples of use
Quote
Chinese astrology teaches that there are five planetary colors: Jupiter the Wood planet is the blue-green of foliage and the sea; Mars the Fire planet is the red of cinnabar, an ore of the metal mercury; Saturn the Earth planet is the color of the yellow ochre of Central China; Venus the metal planet, also known as the Great White is brilliant silvery white, Mercury the water planet with no colour of its own is deemed to be blush-black, the colour of the night sky. Derek Walters in: The Chinese Astrology Bible: The Definitive Guide to Using the Chinese Zodiac, Sterling Publishing Company, Inc., 2009, p. 324
Source: Saturn (Astrology)
Gainsborough's Palette. - This I had from Mr. Briggs, but have lost it; still, as I have copied several Gainsborough's, I think I can furnish you with it. Yellows: yellow ochre, Naples }nllow, yellow lake, and for his high lights (but very seldom) some brighter yellow, probably some preparation of orpiment, raw sienna. Reds: vermilion, light red Venetian, and the lakes. Browns: burnt sienna, cologne earth (this he used very freely, and brown pink the same). He used a great deal of terra verte, which he mixed with his blues, generally with ultramarine. His skies are ultramarine. In his early pictures I could never trace other colours. pp. 63-64
Source: Thomas Gainsborough
