Sienna

Terra di Siena ( Italian " earth of Siena " ), Italian ocher is a yellow to red-brown pigment, named after the earth around the city of Siena in Tuscany (Italy).

The earth color has a typical yellow- brownish color, Sienna. By heating the water of crystallization is removed from the pigment and it gets a red- brown color, which is referred to as burnt sienna.

As color Siena called but only less color saturated Rotgelbtöne: Yellow brown to ocher, umber greenish brown called, more reddish-brown iron oxide red tones.

Nature

The Sienna essentially corresponds to the ocher coloring ingredient is the limonite clay mineral contained. However, it is distinguished from the ocher by the content of colloidal silica.

Use

The pigments can be used in all binders. The real Terra di Siena but is distinguished by its special transparency and degree of opacity, which makes it especially but excels in watercolor, ocher glaze as the best of the mural.

Extraction

The recovery of the earth took in the Siena area until the 1940s. Today, the Siena - earths in other areas of Italy ( Monte Amiata, Sardinia, Sicily), Corsica and North America ( Appalachians ) degraded because the deposits are exhausted in Siena itself. In addition succeeds and the synthetic production.

History

Siena was, among other earth colors the earliest color pigment used people. It can already be detected in stone age cave paintings, which also documents its durability. Frequently encountered it in the excavated Roman towns around Vesuvius ( Pompeii, Herculaneum ).