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PBr7—Burnt Sienna

Pigment Type

earth

Chemical Name

iron oxides

Chemical Formula

Fe₂O₃

Properties

Burnt Sienna is a warm, mid-brown color formed by burning the yellow-brown limonite clay called Raw Sienna. It ranges from semi-opaque to semi-transparent due to the combination of its opaque, red-brown mass tone and its transparent, orangey undertone. It is an excellent mixing complement for blues and greens and creates salmon or peach colored tints when mixed with white. It can be useful for subduing bright colors and does not get chalky in dark mixtures.

Permanence

Burnt Sienna has good permanence and is considered one of the most versatile of the permanent pigments.

Toxicity

Burnt Sienna has no significant hazards.

History

Burnt Sienna has been used as a pigment since prehistoric times, but its current name came about during the Renaissance. It comes from the city of Siena, in Italy, and is short for terra di Siena, meaning earth of Siena. Sienna was famous for the mining and production of earth pigments from the Renaissance until World War II. Due to the depletion of clay deposits in Tuscany, Italian siennas now come from other areas, including Sicily and Sardinia.

Alternate Names

Caput Mortuum, Italian Earth, Natural Brown Iron Oxide, Sienna, Spanish Red, Vandyke Brown.

PY37—Cadmium Yellow

Pigment Type

inorganiic, cadmium

Chemical Name

cadmium(II)-sulfide

Chemical Formula

CdS

Properties

Cadmium Yellow is brilliant, dense, and opaque, with good tinting strength and very high hiding power. It is the artist’s principal bright yellow and is available in light, medium, and dark shades. The deeper shades appear deep orange and have the greatest tinting strength. It is slow-drying in oil form and is used in both oil and watercolor form. It cannot be mixed with copper-based pigments. A clean Cadmium Orange is created when Cadmium Yellow is mixed with Cadmium Red. Hues vary by brand. Cadmium pigments have been partially replaced by azo pigments, which are similar in lightfastness to the cadmium colors, cheaper, and non-toxic.

Cadmium Yellow is usually available in a pure grade, or in a cadmium-barium mix. This mix has the same permanence with a lower tinting strength.

Permanence

Cadmium Yellow is lightfast and permanent in most forms, but like most cadmium colors, it will fade in fresco or mural painting. The deeper shades are the most permanent. The pale varieties have been known to fade with exposure to sunlight.

Toxicity

Cadmium Yellow is a known human carcinogen. It can be hazardous if chronically inhaled or ingested.

History

Cadmiums get their names from the Latin word cadmia meaning zinc ore calamine, and the Greek word kadmeia, meaning Cadmean earth, first found near Thebes, the city founded by the Phoenician prince Cadmus. Metallic cadmium was discovered in 1817 by Friedrich Strohmeyer. Oil colors were first made from Cadmium Yellow pigments in 1819, replacing toxic Chrome (lead) Yellows. However, their production was delayed until 1840 due to the scarcity of cadmium metals. Landscape painters, such as Claude Monet, preferred Cadmium Yellow to the less expensive Chrome Yellow because of its higher chroma and greater purity of color.

Alternate Names

Aurora Yellow, Cadmium Primrose Yellow, Cadmium Zinc Yellow, Lemon Yellow, Primrose Yellow. Deep Cadmium Yellow is sometimes called Orient Yellow.

PB27—Prussian Blue

Pigment Type

inorganic

Chemical Name

ferric ferrocyanide/iron(III)-hexacyanoferrate(II)

Chemical Formula

Fe₇(CN)₁₈(H₂O)_x or C₆FeN₆H₄N

Properties

Prussian Blue is a semi-transparent, deep cyan-blue with a greenish undertone and a very high tinting strength unequaled by most pigments. It is similar to Phthalo Blue unless mixed with white, when it gives up intensity and becomes smoky. It can behave erratically and less reliably in oil and watercolor form depending on its manufacture. For permanent painting Phthalo Blue is considered a more reliable choice.

Permanence

Prussian Blue is lightfast and permanent in all techniques except for fresco. When mixed with Zinc White in watercolor or tempera form, it fades upon exposure to light and completely regains its chromatic strength in the dark. Modern manufacturing techniques have made this tendency less of an issue in recent years

Toxicity

Prussian Blue is moderately toxic if ingested. It will emit toxic hydrogen cyanide gas if heated, exposed to ultraviolet radiation, or treated with acid.

History

"The first of the modern pigments," Prussian Blue is the first artificial pigment with a known history. It was discovered by accident in 1704 by the Berlin color maker Heinrich Diesbach, who was trying to create a pigment with a red hue by mixing iron sulfate and potash. The potash Diesbach purchased from a local laboratory had been contaminated by animal oil and blood during previous experimentation. The resulting mixture yielded a very pale red that changed to purple and then deep blue when he tried to concentrate it. Since previous blue pigments came from lapis lazuli, an expensive stone, Diesbach’s discovery was extremely important for artists of the time.

Alternate Names

Berlin Blue, Bronze Blue, Iron Blue, Paris Blue, Paste Blue. Celestial Blue, Monthier Blue and Soluble Blue are varieties of Prussian Blue. Blue Lake is a reduced or let-down variety of Prussian Blue. Chinese Blue, Milori Blue, and Steel Blue are the three highest grades of Prussian Blue.