Clay earth pigment
Encyclopedia
Clay earth pigments are naturally occurring mineral
s, principally iron oxide
s, that have been used since prehistoric times as pigment
s. The primary types are
Earth pigments are known for their fast drying time in oil painting
, relative inexpensiveness, and lightfastness. Cave paintings done in sienna still survive today.
Mineral
A mineral is a naturally occurring solid chemical substance formed through biogeochemical processes, having characteristic chemical composition, highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not...
s, principally iron oxide
Iron oxide
Iron oxides are chemical compounds composed of iron and oxygen. All together, there are sixteen known iron oxides and oxyhydroxides.Iron oxides and oxide-hydroxides are widespread in nature, play an important role in many geological and biological processes, and are widely utilized by humans, e.g.,...
s, that have been used since prehistoric times as pigment
Pigment
A pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light.Many materials selectively absorb...
s. The primary types are
- ochreOchreOchre is the term for both a golden-yellow or light yellow brown color and for a form of earth pigment which produces the color. The pigment can also be used to create a reddish tint known as "red ochre". The more rarely used terms "purple ochre" and "brown ochre" also exist for variant hues...
- siennaSiennaSienna is a form of limonite clay most famous in the production of oil paint pigments. Its yellow-brown colour comes from ferric oxides contained within...
- umberUmberUmber is a natural brown clay pigment which contains iron and manganese oxides. The color becomes more intense when calcined , and the resulting pigment is called burnt umber. Its name derives from the Latin word umbra and was originally extracted in Umbria, a mountainous region of central Italy,...
Earth pigments are known for their fast drying time in oil painting
Oil painting
Oil painting is the process of painting with pigments that are bound with a medium of drying oil—especially in early modern Europe, linseed oil. Often an oil such as linseed was boiled with a resin such as pine resin or even frankincense; these were called 'varnishes' and were prized for their body...
, relative inexpensiveness, and lightfastness. Cave paintings done in sienna still survive today.
External links
- http://www.iconofile.com/search_results.asp?subcatid=29 (Starting link; has multiple pages. This is a commercial site, but it has many excellent descriptions and pictures of these and other related materials.)