Great American Handmade Pastel - Kermes 3, 370.3

Pigment Information

This color contains the following pigments:

PW18-Calcium Carbonate

PG7-Phthalo Green

PR108-Cadmium Red

Pigment Name

PW18-Calcium Carbonate

Pigment Type

inorganic

Chemical Name

calcium carbonate

Chemical Formula

CaCO3

Properties

Calcium carbonate, the mineral constituent of chalk, is a low tinting strength, inexpensive white pigment that is often used is a buffer and filler. Because of its low tinting strength, it is overwhelmed by other colors. It is used in gesso and other coatings to give the surface more tooth, a desirable characteristic for some painting techniques.

Permanence

Calcium carbonate is lightfast. Like all carbonates, it reacts with strong acids

Toxicity

Calcium carbonate is completely non-toxic, and is used in many food, cosmetic, and pharmaceutical products. However, excessive consumption is not recommended. 

History

Naturally occuring chalk deposits have been mined since prehistoric times. Rocks and minerals that contain calcium carbonate include aragonite, calcite, vaterite, chalk, limestone. marble, and travertine. Calcium carbonate is the principle component of lime, used in many agricultural and industrial applications.

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.

Pigment Name

PR108-Cadmium Red

Pigment Type

inorganic, cadmium

Chemical Name

cadmium sulfide and cadmium selenide

Chemical Formula

CdS x CdSe

Properties

Cadmium Red is a bright, warm red that ranges in shade from orange-red to maroon and is available in light, medium, and dark versions. It is strong and opaque, with good tinting strength. Cadmium Red dries slowly. It grays down when mixed with white, mixes well with blues to create a range of browns, and mixes well with Cadmium Yellow to create a strong orange. It also works well in neutral mixes. Cadmium pigments have been partially replaced by azo pigments, which are similar in lightfastness to the cadmium colors, cheaper, and non-toxic. Hues vary by brand. Cadmium Red is usually available in either a pure grade or a cadmium-barium mix. The cadmium-barium mix has the same permanence as pure Cadmium Red, but it has a lower tinting strength.

Permanence

Cadmium Red is lightfast and permanent in most forms, but like many cadmium pigments, it will fade in fresco or mural painting. Its improved lightfastness has helped it to replace Vermilion on the artist’s palette.

Toxicity

Cadmium Red 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, but Cadmium Red was not introduced until 1907 in Germany.