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PY3—Hansa Yellow 10G

Pigment Type

organic, monoazo

Chemical Name

n/a

Chemical Formula

C₁₆H₁₂CL₂N₄O₂

Properties

This Hansa yellow is a transparent yellow. It has great brightness and tinting strength and its drying time ranges from average to slow.

Hansa Yellow makes more intense tints and cleaner secondaries than Cadmium Yellows, especially when mixed with other organic or modern colors like Phthalo Blue and Green. Because they are more transparent, they have great value as glazing colors.

Permanence

This Hansa Yellow has fair to good permanence, particularly in the lighter shades.

Toxicity

Hansa Yellow has no significant acute hazards, though its chronic hazards have not been well studied.

History

Hansa Yellows were first made in Germany just before WW1 from a series of synthetic dyestuffs called Pigment Yellow. They were intended to be a synthetic replacement for Cadmium Yellow.

Alternate Names

Arylamide Yellow, Arylide, Arylide Yellow, Azo, Brilliant Yellow, Monoazo, Monolite Yellow, Permanent Yellow.

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.

PG18—Viridian

Pigment Type

inorganic

Chemical Name

chromium(III)-oxide dehydrate

Chemical Formula

Cr₂O₃ • 2 H₂O or Cr₂(OH₃)

Properties

Viridian is the standard green and is stable, powerful, and cold with an emerald green undertone. It has a transparent hue, good tinting strength, a dark masstone that can be almost black at full strength, and a slow drying time in oil form. Viridian is commonly replaced by the darker, more saturated, and staining Phthalo Greens, but its properties make it a necessary part of the palette of an experienced landscape painter.

Permanence

Viridian has excellent permanence, except in high-temperature work, and is highly valued as a glazing color.

Toxicity

Viridian is slightly toxic.

History

Viridian’s name comes from the Latin viridis, meaning green. The process for manufacturing Viridian, or Transparent Oxide of Chromium, was patented by Guignet in Paris in 1859. However, it had actually been discovered by Pannetier and Binet in 1838. Viridian replaced Verdigris, which was reactive and unstable, and Emerald Green, which was a poisonous copper aceto-arsenite used as a rat poison in the sewers of Paris.

Alternate Names

Emerald Chromium Oxide, Emeraude Green, French Veronese Green, Guignet’s Green, Pannetier's Green, Permanent Green, Smaragd Green, Transparent Oxide of Chromium, Vert Emeraude. Casali's Green and Mittler's Green are varieties of Viridian. Viridian has historically been sold under the name Emerald Green, but they are currently considered to be and are marketed as two different pigments.