This color contains the following pigments:
PR101-Red Iron Oxide
iron oxides with manganese silicates or dioxide
Fe2O3,MnO2 or Fe2O3+MnO2+nH2O+Si+Al2O3
Burnt Umber is a more intense reddish brown pigment that results from heating the clay pigment Raw Umber. It has medium to excellent tinting strength and high opacity, and it is quick drying in oil form. Burnt Umber is somewhat more transparent than Raw Umber. It has excellent color properties and can create a variety of subtle, clear tints when mixed with white. It can tend towards chalkiness in dark mixes in oil form, but overall it mixes well with other colors. To create a black color in oil form, mix Burnt Umber with Phthalo Blue or Ultramarine. To achieve a similar color in watercolor form, mix it with Ultramarine or Payne's Gray.
Burnt Umber has good permanence.
Burnt Umber itself is considered non-toxic. If contaminated by manganese compounds, it may be highly toxic if inhaled and moderately toxic if ingested.
This pigment gets its name from the Latin word umbra, meaning shadow or shade. Its full name is listed as terra di ombra, meaning earth of shadow/shade, due to its original extraction from the area of Umbria, Italy. It has been used as a pigment since prehistoric times. Currently, the finest umber comes from Cyprus.
PR101-Red Iron Oxide
iron oxides (synthetic), iron oxide, silica, alumina, lime, and magnesia or hydrated iron oxide
Fe2O2 or Fe2O3 x H2O
Red iron oxide varies in hue and transparency, depending on hydration and slight impurities. Indian Red is a slightly duller, deep brick hue with a bluish undertone. It is very dense and opaque, with excellent tinting strength and covering power. It is dependable when mixing with all other permanent pigments and yields good flesh tints when mixed with Zinc White. It is the synthetic version of PR102, which is a pigment made from earth reds, or natural red iron oxides, and the names applied to PR101 and PR102 often overlap. The synthetic red iron oxides have mostly replaced natural red iron oxides and are brighter, stronger, finer, and more permanent. Indian Red is the highest grade bluish shade. Light Red, English Red, and Venetian Red are yellowish shades. Mars Violet is a dull and subdued bluish or purplish oxide.
Red iron oxide is very lightfast with excellent permanence.
Red iron oxide has no significant hazards.
Natural red iron oxide comes from the mineral ore hematite, called bloodstone by the ancient Greeks from the word hema, meaning blood. It is one of the oldest pigments, has been used by every major civilization, and was an important mineral for medieval alchemists. It was not widely used in artists' materials until the 17th century and was not produced in large quantities until the 18th century.