This color contains the following pigments:
complex silicate of sodium and aluminum with sulfur
Na8-10Al6Si6O24S2-4 or Na6-8Al6Si6O24S2-4
Ultramarine is the standard warm blue, a brilliant blue pigment that has the most purple and least green in its undertone. It has a moderate to high tinting strength and a beautiful transparency. Synthetic Ultramarine is not as vivid a blue as natural Ultramarine. Ultramarine dries slowly in oil and tends to produce clean, though granular, washes in watercolor. French Ultramarine mixes well with Alizarin colors in oil and watercolor form to create a range of purples and violets. It can dull when mixed with white in acrylic form, but mixes well with other colors. The shade varies based on manufacturer. Considered a great color for glazes, it is not suitable for frescoing.
Ultramarine has excellent permanence, although synthetic Ultramarine is not as permanent as natural Ultramarine. It may discolor if exposed to acid because of its sulfuric content.
Ultramarine has no significant hazards.
The name for this pigment comes from the Middle Latin ultra, meaning beyond, and mare, meaning sea, because it was imported from Asia to Europe by sea. It is a prominent component of lapis lazuli and was used on Asian temples starting in the 6th century. It was one of the most expensive pigments in 16th century Europe, worth twice its weight in gold, and so was used sparingly and when commissions were larger. Ultramarine is currently imitated by a process invented in France in 1826 by Jean Baptiste Guimet, making blue affordable to artists and extending the range of colors on their palettes.
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.