Bob Ross Oil Color - Midnight Black, 1.25 oz tube

Pigment Information

This color contains the following pigments:

PR83-Alizarin Crimson

PG7-Phthalo Green

Pigment Name

PR83-Alizarin Crimson

Pigment Type

organic

Chemical Name

1,2-dihydroxyantraquinone

Chemical Formula

C14H8O4

Properties

Alizarin Crimson, the traditional cool counterpart to Cadmium Red, is a clear ruby-red with a maroon masstone and a bluish undertone. It is the artist's principal deep red pigment, is transparent, and has good tinting strength. It creates bright rosy pinks when mixed with white, a range of purples and violets when mixed with strong blues, can be slow drying when used with oils, and is compatible with all other pigments. Permanent Alizarin Crimson mixes well with Ultramarine in acrylic and watercolor form. Permanent Rose and Quinacridone Rose are possible alternatives on a watercolor palette. Alizarin Crimson is a popular glazing color.

Permanence

Alizarin Crimson is considered fugitive or marginally lightfast, and the appropriateness of its use in the modern artist palette is a subject of debate. There are many concerns regarding its permanence, particularly when mixed with ochre, sienna, and umber, or when used thinly. It is the least permanent red commonly used by today's artists. Modern synthetic preparations of Alizarin Crimson have better permanence and lightfastness that the original natural pigment, which was extracted from the madder plant. Quinacridone pigments have been used to create a modern hue that closely matches the original hue, but many artists object that the transparency and handling characteristics are not the same as for the original.

Toxicity

Alizarin Crimson can be slightly toxic if it comes into contact with skin and may cause some allergies. There is no significant acute toxicity.

History

The word alizarin comes from the Arabic word al-usara, meaning juice. The base ingredient of this pigment is the Madder plant (Rubia Tinctorum). It was used for dyes and inks among craftsmen in Ancient Persia, India, and Egypt as early as 1500 BC In 1804, George Field, an English dye maker, developed Madder Lake by binding madder to alum, a white powder. The German chemists Carl Grabe and Carl Liebermann produced the first synthetic variety of this pigment, most commonly known as Alizarin Crimson, in 1868. They used anthracene, which greatly improved the lightfastness. The Colour Index International designation PR83:1 has been used to identify this synthetic laked pigment.

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.