Raw Sienna

Colour: Raw Sienna
Permanence: AA
Opacity: Semi-transparent
Pigment: PBr7
Pigment description: Natural Iron Oxide
ASTM Rating Ligthfastness: I
Pigment classification: Natural inorganic
Color Index Number: -
Viscosity range (mPa.s): 20.000 - 25.000

Color Index
The pigments used for artists' colours are inorganic as well as organic. The inorganic pigments have been used since antiquity; most of them are extracted from minerals and soil, such as natural earth colours, siennas and ochres. Titanium, carbon and ultramarine pigments also belong to this category, as well as cobalt and cadmium. Many of these pigments are now also manufactured synthetically. Organic pigments have their origins in the 19th century. Industrial production developed at the beginning of the twentieth century owing to new manufacturing processes in organic chemistry. These synthetic pigments have become an important group in the manufacture of artists' colours, producing bright and luminous shades of great intensity and excellent light fastness and permanence. The range has extended continuously, and now besides the familiar phthalocyanines and naphthols, includes azo compounds, dioxacines and pyrroles, antraquiniones and quinacridones.