Holbein Artists' Gouache - Turquoise Blue, 15 ml tube

Pigment Information

This color contains the following pigments:

PB35-Cerulean Blue

PB15-Phthalo Blue

PG7-Phthalo Green

Pigment Name

PB35-Cerulean Blue

Pigment Type

inorganic

Chemical Name

cobalt(II) stannate

Chemical Formula

CoO n SnO2

Properties

Cerulean Blue is the standard cool blue, considered the traditional counterpart to Ultramarine, and is often used for painting atmospheric shades. It is quick drying and retains its color well, better than any other blue, in oil paint form. However, it tends to granulate or become chalky in watercolors. It has limited hiding power, is semi-opaque, and is easy to control. Its tinting capacity is low, so it can become lost when mixing.

Permanence

Cerulean Blue has excellent permanence. It is very stable and lightfast.

Toxicity

Cerulean Blue is moderately toxic if inhaled or ingested and slightly toxic if it comes into contact with skin.

History

The name Cerulean Blue comes from the Latin word caelum, meaning sky. This pigment was discovered in 1805 by Andreas Hopfner, but it was not widely available until introduced by Messrs. G. Rowney & Co. in England under the name coeruleum in 1860 for use in aquarelle and oil painting. It was produced by the action of heat on cobalt oxide and other metallic bases.

Pigment Name

PB15-Phthalo Blue

Pigment Type

organic

Chemical Name

copper phthalocyanine

Chemical Formula

C32H16CuN8

Properties

Phthalo Blues are pure and clean primary blues with superior covering power. They have a very high tinting strength and tend to overwhelm other pigments, but if color strength can be controlled, they make predictable mixed colors. In oil form, blues are very deep and slow drying. When mixed with other colors or if chlorine is added, Phthalo Blue quickly tends towards green. When using alone, mix with some white, as Phthalo Blue can be semi-transparent and almost black on its own. It is among the most compatible of modern colors with mineral colors and is considered more reliable than Prussian Blue, while sharing the same physical and color properties. Phthalo Blue is a good color for glazing.

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.

Pigment Name

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.