Cadmium pigments are a class of

pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compounds whereas pigments are often inorganic comp ...

s that contain

cadmium Cadmium is a chemical element with the symbol Cd and atomic number 48. This soft, silvery-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Like zinc, it demonstrates oxidation state +2 in most of ...

. Most of the cadmium produced worldwide has been for use in rechargeable nickel–cadmium batteries, which have been replaced by other rechargeable nickel-chemistry cell varieties such as NiMH cells, but about half of the remaining consumption of cadmium, which is approximately annually, is used to produce colored cadmium pigments. The principal pigments are a family of yellow, orange and red cadmium

sulfide Sulfide (British English also sulphide) is an inorganic anion of sulfur with the chemical formula S2− or a compound containing one or more S2− ions. Solutions of sulfide salts are corrosive. ''Sulfide'' also refers to chemical compounds l ...

s and sulfoselenides, as well as compounds with other metals. Cadmium is toxic to humans and other animals in very small amounts, especially when it is inhaled, which often happens when working with powdered pigment or breathing the dust from chalk pastels. As a result, it is not appropriate for children to use any art supplies that contain cadmium pigments. However, because the pigments have some desirable qualities, such as resistance to fading, some adult artists continue to use them.

Artists' paints

Brilliantly colored, with good permanence and tinting power, cadmium yellow, cadmium orange and cadmium red are familiar artists’ colors, and are frequently employed as architectural

paint Paint is any pigmented liquid, liquefiable, or solid mastic composition that, after application to a substrate in a thin layer, converts to a solid film. It is most commonly used to protect, color, or provide texture. Paint can be made in many ...

s, as they can add life and vibrancy to renderings. Their greatest use is in the coloring of

plastic Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be moulded, extruded or pressed into solid objects of various shapes. This adaptab ...

s and specialty paints, which must resist processing or service temperatures up to . The colorfastness or permanence of cadmium requires protection from the element's tendency to slowly form carbonate salts with exposure to air. Most paint vehicles accomplish this, but cadmium colors will fade in fresco or mural painting. The following are commonly used as pigments in artists' paints: * Cadmium yellow is

cadmium sulfide Cadmium sulfide is the inorganic compound with the formula CdS. Cadmium sulfide is a yellow solid.Egon Wiberg, Arnold Frederick Holleman (2001''Inorganic Chemistry'' Elsevier It occurs in nature with two different crystal structures as the rare mi ...

(CdS), C.I. Pigment Yellow 37. * Cadmium sulfoselenide is a solid solution of CdS and cadmium selenide; depending on the

sulfur Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formul ...

-to-

selenium Selenium is a chemical element with the symbol Se and atomic number 34. It is a nonmetal (more rarely considered a metalloid) with properties that are intermediate between the elements above and below in the periodic table, sulfur and telluriu ...

ratio, C.I. Pigment Orange 20 or C.I. Pigment Red 108 is obtained. * Zinc cadmium sulfide is a greenish, solid solution of CdS and

zinc sulfide Zinc sulfide (or zinc sulphide) is an inorganic compound with the chemical formula of ZnS. This is the main form of zinc found in nature, where it mainly occurs as the mineral sphalerite. Although this mineral is usually black because of various i ...

, C.I. Pigment Yellow 35. * Cadmium yellow is sometimes mixed with viridian to give a bright, pale green mixture called cadmium green. When first introduced, there were hardly any stable pigments in the yellow-to-red range, with orange and bright red being very troublesome. The cadmium pigments eventually replaced compounds such as mercury(II) sulfide (the original

vermilion Vermilion (sometimes vermillion) is a color, color family, and pigment most often made, since antiquity until the 19th century, from the powdered mineral cinnabar (a form of mercury sulfide, which is toxic) and its corresponding color. It i ...

) with greatly improved lightfastness. Cadmium pigments are known for excellent lightfastness, although the lighter shades can fade in sunlight. A cadmium yellow paint was frequently used on Bob Ross' TV show '' The Joy of Painting''.

Coloring art glass

Cadmium compounds are utilized in coloring

borosilicate glass Borosilicate glass is a type of glass with silica and boron trioxide as the main glass-forming constituents. Borosilicate glasses are known for having very low coefficients of thermal expansion (≈3 × 10−6 K−1 at 20 °C), m ...

used by artists in lampworking. The palette is often referred to as "cadmium colors" or "cadmium-based colors" and is marked by uniquely bright and saturated tones not found in other colored glass. Cadmium pigments used in borosilicate have a relatively short history, with the first commercial formulations hitting the market in 2000 under the name Crayon Colors by Henry Grimmett of Glass Alchemy. Cadmium-compound-containing glass exhibits a characteristically low heat tolerance when melted, and therefore must be treated with caution when lampworking to avoid boiling off of the

. CdS has a boiling point of , putting its maximum temperature tolerance as a pigment not far above the working temperature range for borosilicate, which has a softening point of approximately .

Safety

Cadmium sulfide is not very toxic ( above 5,000 mg/kg). Cadmium is introduced into the body most commonly through smoking and the diet. Poisoning by pigments is uncommon but of continuing concern.Acute exposure to cadmium vapors can arise from

welding Welding is a fabrication process that joins materials, usually metals or thermoplastics, by using high heat to melt the parts together and allowing them to cool, causing fusion. Welding is distinct from lower temperature techniques such as br ...

near cadmium pigments. The cadmium pigments have been partially replaced by azo pigments, which have significantly inferior lightfastness. In December 2013, the Swedish Chemicals Agency ( KEMI) proposed a case to the European Chemicals Agency ( ECHA) in favor of restricting or banning cadmium use in artists’ paints, as cadmium in pigments used in other types of paints was already restricted and regulated via TARIC codes and

REACH Reach or REACH may refer to: Companies and organizations * Reach plc, formerly Trinity Mirror, large British newspaper, magazine, and digital publisher * Reach Canada, an NGO in Canada * Reach Limited, an Asia Pacific cable network company * ...

Annex XVII. This proposal stated that cadmium in the body leads to increased risk of bone fractures and breast cancer as well as an array of environmental impacts, and that paint washed down the drain is absorbed by crops that are then consumed, increasing the average dietary cadmium intake. This can cause an array of health effects, including kidney and liver damage, skeletal damage, several types of cancers and death. KEMI's proposal was ultimately declined. In a June 2015 article of ''Just Paint,'' published by Golden Artist Colors, the company argued against KEMI's proposal, offering that "There are no alternatives that match all of the characteristics of cadmium pigments." This statement was also included in Golden's response to KEMI's request for information on cadmium-pigmented artists’ paints while the agency was composing its ban proposal. The article also stated that a ban would be technically feasible for some artists, but not all, and that "cadmium colors are not for use by children, should not be spray applied or sanded, and unless one is properly protected from exposure and in a non-household setting, use of dry cadmium pigment should be avoided." Inhalation poses the greatest risk from cadmium pigments, though the chemical is very low-risk when sealed within a pigment particle because of its insolubility. The use of chalk pastels containing cadmium colors is among the highest risks for artists, as these pastels create a dust that can be inhaled.

Examples of cadmium pigments in art

Winslow Homer - Hunter in the Adirondacks (1892).jpg ,

Winslow Homer Winslow Homer (February 24, 1836 – September 29, 1910) was an American landscape painter and illustrator, best known for his marine subjects. He is considered one of the foremost painters in 19th-century America and a preeminent figure ...

, "Hunter in the Adirondacks" (1892) Grapes, Lemons, Pears, and Apples 1887 Vincent van Gogh.jpg ,

Vincent van Gogh Vincent Willem van Gogh (; 30 March 185329 July 1890) was a Dutch Post-Impressionist painter who posthumously became one of the most famous and influential figures in Western art history. In a decade, he created about 2,100 artworks, inc ...

, "Grapes, Lemons, Pears, and Apples" (1887) 1278 Wheatstacks (Sunset, Snow Effect), 1890-91, 65.3 x 100.4 cm, 25 11-16 x 39 1-2 in., The Art Institute of Chicago.jpg ,

Claude Monet Oscar-Claude Monet (, , ; 14 November 1840 – 5 December 1926) was a French painter and founder of impressionist painting who is seen as a key precursor to modernism, especially in his attempts to paint nature as he perceived it. During ...

, "Wheatstacks (Sunset, Snow Effect)" (1890–91) Monet-Still-Life-with-Apples-and-Grapes-1880.jpg ,

, "Still Life with Apples and Grapes" (1880)

References

External links

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Cadmium yellow
ColourLex
Cadmium orange
ColourLex
Cadmium red
ColourLex {{DEFAULTSORT:Cadmium Pigments Pigments Inorganic pigments Cadmium compounds Sulfides Shades of red Shades of orange Shades of green Shades of yellow