BURNT SIENNA
Burnt Sienna is a variation of Sienna earth. Extracted from the same iron deposits in Tuscany, it is then calcined in furnaces at a temperature of 450 degrees Celsius. During this process, hydrated iron oxides lose water and turn into iron oxides ( haematite) with the colour getting darker hues of brown-orange.
Chemical formula Fe2O3 • nH2O + MnO + Al2O3• SiO2+ SiO2
Stability to light 7 (scale 1/8)
Specific weight 2,60
For fresco, tempera, oil, encaustic
