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PG17—Chromium Oxide Green

Pigment Type

inorganic

Chemical Name

chromium oxide

Chemical Formula

Cr₂O₃

Properties

Chromium Oxide Green is a dull, dense, willow or pale green color that is completely opaque. It has an average drying time and a low tinting strength. It is fairly flexible in oil form and is suitable for all purposes and mediums. This pigment is less versatile in mixtures than Viridian and Phthalocyanine Green, but mixes well with other colors without overpowering them.

Permanence

Chromium Oxide Green has excellent permanence, even at high temperatures.

Toxicity

Chromium Oxide Green is slightly toxic. Evidence of Chromium(III) carcinogenicity is inconclusive. Chromium(III) salts appear in greenish pigments such as PG17. Chromium(VI) salts, which appear in yellowish pigments, have been proven to cause cancer. 

History

Louis-Nicolas Vauquelin discovered the element chromium in lead chromate in 1797. It began to be used as an enamel and ceramic color in 1809, but it had limited use as a pigment until 1862, because of its cost. It is the most commonly used green for military camouflage because it appears the same shade as living foliage under infrared light.

Alternate Names

Chrome Oxide Green, Olive Green, Permanent Green. Varieties of Chromium Oxide Green include Arnaudon's Green, Dingler's Green, Plessy's Green, and Schnitzer's Green.

PG7—Phthalo Green

Pigment Type

organic

Chemical Name

polychlorinated copper(II) phthalocyanine

Chemical Formula

C₃₂H₃Cl₁₃CuN₈ to C₃₂HCl₁₅CuN₈ or C₃₂H₁₆CuN₈Cl₁₅ (PG7) or C₃₂Br₆Cl₁₀CuN₈ (PG36)

Properties

Phthalo Green is a transparent, cool, bright, high intensity color used in oil and acrylics. It comes from a Phthalocyanine Blue pigment where most of the hydrogen atoms have been replaced with chlorine, forming highly stable molecules.  It has similar pigment properties and permanence to Phthalo Blue. It is slow drying and an excellent base color for mixing a range of bright greens. Phthalo Green is considered a very good alternative to Viridian because it is intense and mixes well and can be used to emphasize mineral colors in various tints. However, its tinting strength is very high, so it can overpower other colors.  This pigment most closely resembles the discontinued and toxic Verdigris.

Permanence

Phthalo Greens are completely lightfast and resistant to alkali, acids, solvents, heat, and ultraviolet radiation. They are currently used in inks, coatings, and many plastics due to their stability and are considered a standard pigment in printing ink and the packaging industry.

Toxicity

Phthalo Green has no significant hazards, but it contained PCBs (polychlorinated biphenyls) until 1982.

History

This bright blue-green was developed in 1935 and has been in use since 1938.

Alternate Names

Bocour Green, Cyan Green, Intense Green, Monastral Green, Phthalocyanine Green, Rembrandt Green, Thalo Green, Winsor Green.

PBk11—Mars Black

Pigment Type

earth

Chemical Name

iron oxides

Chemical Formula

FeO or Fe₂O₃

Properties

Mars Black is an opaque black with a strong and cool masstone, a slightly warm tint, and a warm brown undertone. It is not as black as Ivory Black, but it dries more quickly and has three times the tinting strength. Mars Black is normally the only black available in acrylic form and that is safe to over paint. It can be used in all media without reservation and is widely used as an alternative to Lamp Black and Ivory Black.

Permanence

Mars Black is very lightfast with excellent permanence.

Toxicity

Mars Black has no significant hazards and is the only major black pigment considered non-toxic.

History

The word Mars refers to the Roman god of iron and war. Mars Black was developed in the early 20^th century from inorganic, synthetic iron oxide.

Alternate Names

Black Iron Oxide, Iron Black, Magnetic Oxide, Mapico Black, Mineral Black. Sometimes labeled as Vine Black.

PB15:3—Phthalo Blue

Pigment Type

organic

Chemical Name

beta copper phthalocyanine

Chemical Formula

C₃₂H₁₆CuN₈

Properties

Phthalo Blue PB15:3 is a structural variant of Phthalo Blue PB15 that produces more greenish tones.

Permanence

Phthalo Blues are completely lightfast and stable and are permanent for all paint uses. They are currently used in inks, coatings, and many plastics due to their stability and are considered a standard pigment in printing ink and the packaging industry.

Toxicity

Phthalo Blues have no significant hazards, although those made before 1982 contained some PCBs (polychlorinated biphenyls).

History

Developed by chemists using the trade name Monastral Blue, the organic blue dyestuff now known as Phthalo Blue was presented as a pigment in November 1935 in London. Its discovery was accidental. The dark color was observed in a kettle where a dye was being made from a British dyestuff plant. The demand for such a pigment came from commercial printers who wanted a cyan to replace Prussian Blue.

Alternate Names

Phthalo Blue Green Shade, Winsor Blue Green Shade