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PW7—Zinc Sulphide White

Pigment Type

inorganic

Chemical Name

zinc sulfide

Chemical Formula

ZnS

Properties

Zinc Sulphide White is a semi-transparent yellowish white pigment. Zinc sulfide and zinc oxide (PW4) are often combined to create a more natural white color. Transparency increases as particle size decreases. When slight impurities are added, zinc sulphide has phospherescent and electroluminescent properties. It is often used to manufacture fluorescent or glow-in-the-dark paints.

Permanence

Zinc Sulphide White has excellent permanence and lightfastness.

Toxicity

Zinc Sulphide is non-toxic, but ore deposits often contain lead. Traces of lead and other impurities may be present in pigment powders. Ingestion is not recommended.

History

Zinc sulfide, when combined with slight impurites, has phospherescent properties. It is often used for "invisible ink" that glows with exposure to ultraviolet light. Zinc sulfide is used in the manufacture of fluorescent paints.

Alternate Names

Chinese White

PO20—Cadmium Orange

Pigment Type

cadmium

Chemical Name

cadmium sulfide and cadmium selenide

Chemical Formula

CdS × CdSe

Properties

Cadmium Orange was the first true orange and was made by mixing Cadmium Yellow with Cadmium Red. It is a pure hue with excellent opacity and low toxicity compared with its predecessors. It also has very high hiding power. The greatest tinting strengths are possessed by the deeper shades. Only the highest grades contain pure Cadmium Orange without barium mixed in it. Cadmium pigments have been partially replaced by azo pigments, which are similar in lightfasness to the cadmium colors, cheaper, and non-toxic.

Permanence

Cadmium Orange has excellent permanence, but like many cadmium pigments, it will fade in fresco or mural painting. The deeper varieties of this pigment are the most permanent. The paler varieties have been known to fade when exposed to sunlight.

Toxicity

Cadmium Orange is a known human carcinogen. It is extremely toxic if inhaled and slightly toxic if 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. It was used sparingly after its discovery due to the scarcity of cadmium metal.

Alternate Names

n/a

PY42—Mars Orange

Pigment Type

inorganic, earth

Chemical Name

iron oxide

Chemical Formula

Fe₂O₂ or Fe₂O₃ • H₂O

Properties

Mars Orange is a bright, extremely light red and appears almost pinkish in contrast with darker colors. It has incredible tinting strength and opacity. The synthetic form of Mars Orange is made from iron oxides and is cleaner, brighter, and denser than its ochre-based counterparts.

Permanence

Mars Orange has excellent permanence and lightfastness.

Toxicity

Mars Orange has no significant hazards.

History

The word Mars refers to the Roman god of iron and war. Mars Orange has been manufactured as a pigment since the 17^th century.

Alternate Names

n/a

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.