Cadmium pigments

Cadmium pigments are a class of pigments that have cadmium as one of the chemical components. Most of the cadmium produced worldwide has been used in the production of rechargeable nickel-cadmium batteries — themselves being replaced by other rechargeable nickel-chemistry cell varieties like NiMH cells[2] — but about half the remaining consumption of cadmium, which is about 2,000 tonnes (2,200 short tons) annually, is used to produce colored cadmium pigments. The principal pigments are a family of yellow, orange and red cadmium sulfides and sulfoselenides as well as compounds with metals other than cadmium.[3]

Cadmium orange
 
Cadmiumorange- Pigment
Orange cadmium pigment
    Color coordinates
Hex triplet#ED872D
sRGBB  (rgb)(237, 135, 45)
CMYKH   (c, m, y, k)(0, 43, 81, 7)
HSV       (h, s, v)(28°, 81%, 93%)
Source[1] Charts
B: Normalized to [0–255] (byte)
H: Normalized to [0–100] (hundred)
Cadmium red
 
Kadmiumrot
Red cadmium pigment
    Color coordinates
Hex triplet#E30022
sRGBB  (rgb)(227, 0, 34)
CMYKH   (c, m, y, k)(0, 100, 85, 11)
HSV       (h, s, v)(351°, 100%, 89%)
Source[1]
B: Normalized to [0–255] (byte)
H: Normalized to [0–100] (hundred)
Cadmium green
 
    Color coordinates
Hex triplet#006B3C
sRGBB  (rgb)(0, 107, 60)
CMYKH   (c, m, y, k)(100, 0, 44, 58)
HSV       (h, s, v)(154°, 100%, 42%)
Source[1]
B: Normalized to [0–255] (byte)
H: Normalized to [0–100] (hundred)
Cadmium yellow
 
Cadmiumgelb- Pigment
Yellow cadmium pigment
    Color coordinates
Hex triplet#FFF600
sRGBB  (rgb)(255, 246, 0)
CMYKH   (c, m, y, k)(0, 4, 100, 0)
HSV       (h, s, v)(58°, 100%, 100%)
Source[1]
B: Normalized to [0–255] (byte)
H: Normalized to [0–100] (hundred)

Artists' paints

Cadmium-Hemimorphite-Smithsonite-nex15a
Cadmium-rich hemimorphite crusted on smithsonite
Cadmium sulfide
Cadmium sulfide

Brilliantly colored, with good permanence and tinting power, cadmium yellow, cadmium orange and cadmium red are familiar artists’ colors, as well as being frequently employed as architectural paints, since they can add life and vibrancy to renderings. Their greatest use is in the coloring of plastics and specialty paints which must resist processing or service temperatures up to 3,000 °C (5,430 °F).[4] The color-fastness or permanence of cadmium requires protection from a 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 (CdS): C.I. Pigment Yellow 37.
  • Cadmium sulfoselenide is a solid solution of CdS and cadmium selenide: depending on the sulfur to selenium 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: 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) with greatly improved light-fastness.

Cadmium pigments are known for excellent light-fastness, although the lighter shades can fade in sunlight.[5] A cadmium yellow paint was frequently used on Bob Ross' TV show, The Joy of Painting.

Coloring art glass

Cadmium color rods
Borosilicate glass colored with cadmium compounds.

Cadmium compounds are utilized in coloring borosilicate glass[6] 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.[7]

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 cadmium sulfide. CdS has a boiling point of 980 °C (1,800 °F), putting its maximum temperature tolerance as a pigment not far above the working temperature range for borosilicate, which has a softening point of approximately 850 °C (1,560 °F).[8][9]

Safety

Cadmium orange cast iron pot
Cadmium orange cast-iron pot

Cadmium sulfide is not very toxic (LD50 above 5,000 mg/kg) when used as a pigment, although acute exposure to cadmium vapors from welding is harmful.[3]

The cadmium pigments have been partially replaced by azo pigments. These have significantly inferior lightfastness,[10] but still good,[11] and they have the advantage of both being cheaper and non-toxic. In some countries, consumer activists such as Michael Vernon in Australia were successful in banning the use of cadmium pigments in plastics that could be used for toy manufacture, owing to the toxicity of cadmium.

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 pigments used in artists’ paints, as cadmium in pigments used in other types of paints was already restricted and regulated via TARIC codes and REACH Annex XVII. This proposal stated that cadmium in the body leads to increased risk of bone fractures and breast cancer and an array of environmental impacts. Ultimately, this proposal was declined.

In an article of Just Paint published by Golden Artist Colors in June 2015, the rejection of the cadmium pigment ban proposal by KEMI is discussed alongside the fact that regardless, cadmium pigmented paints, artists’ or otherwise, may not always be legal. They state, “There are no alternatives that match all of the characteristics of cadmium pigments,” a statement that was also directly quoted from Golden's response to KEMI's request for information on cadmium pigmented artists’ paints while they were composing their ban proposal. The article continues, stating 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.” [12] [13]

Inhalation is the biggest risk of these pigments, though cadmium is very low-risk sealed within a pigment particle due to insolubility. The use of chalk pastels containing cadmium colors is of the highest risks when it comes to relevant artist media, since as the pastel is used it is creates a dust which can be inhaled, unlike when using paints.[14]

KEMI's proposal stated that paint washed down the drain is absorbed by crops, which in turn are consumed and increase 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.[15] [16] [17] Cadmium is introduced into the body most commonly through smoking, and in individuals who do not smoke, the next most common instance is through dietary consumption.[18]

Examples of cadmium pigments in art

Winslow Homer - Hunter in the Adirondacks (1892)

Winslow Homer, "Hunter in the Adirondacks" (1892)

Grapes, Lemons, Pears, and Apples 1887 Vincent van Gogh

Vincent van Gogh, "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

Claude Monet, "Wheatstacks (Sunset, Snow Effect)" (1890–91)

Monet-Still-Life-with-Apples-and-Grapes-1880

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

See also

References

  1. ^ a b c d "THE MOTHER OF ALL HTML COLOR CHARTS index and reference | Color World | Color, Chart, Color names". Pinterest. Retrieved 11 May 2019.
  2. ^ "MEPs Ban Cadmium from Power Tool Batteries and Mercury from Button Cells". European Parliament.
  3. ^ a b Müller, Hugo; Müller, Wolfgang; Wehner, Manfred; Liewald, Heike. "Artists' Colors". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a03_143.pub2.
  4. ^ "Cadmium Pigments". Retrieved 30 November 2010.
  5. ^ Douma, Michael (2008), "History of Cadmium Yellow", Pigments Through the Ages, retrieved 2013-07-31
  6. ^ "Borosilicate glass material properties". Adams & Chittenden Scientific Glass. Retrieved 12 April 2019.
  7. ^ "About Us". Glass Alchemy. Retrieved 2018-11-05.
  8. ^ Weissler, G. L.; Carlson, R. W., eds. (1980). Vacuum Physics and Technology (1st ed.). New York: Academic Press. ISBN 9780124759145. OCLC 5170642.
  9. ^ "Cadmium sulfide". PubChem. NCBI. Retrieved 2018-11-05.
  10. ^ Johansen, Tony (2006-05-06). "Yellow". Making Artist's Paint. Retrieved 2013-07-31.
  11. ^ Jill (2010-01-06). "Yellow". Art School at Home. Retrieved 2013-07-31.
  12. ^ Gavett, Ben. "Will Cadmium Colors Always be on the Palette? (Part 2)". Just Paint. Golden Artist Colors, Inc. Retrieved 5 December 2018.
  13. ^ "Annex XV restriction: Report proposal for a restriction" (PDF). ECHA. Retrieved 5 December 2018.
  14. ^ Hoakley (15 June 2018). "Pigment: Controversial Cadmiums, yellow to red". The Eclectic Light Company. Retrieved 5 December 2018.
  15. ^ Kawasaki, Takashi; Kono, Koichi; Dote, Tomotaro; Usuda, Kan; Shimizu, Hiroyasu; Dote, Emi (2004). "Markers of cadmium exposure in workers in a cadmium pigment factory after changes in the exposure conditions". Toxicology and Industrial Health. 20 (1–5): 51–56. doi:10.1191/0748233704th189oa. PMID 15807408.
  16. ^ Kim, Hyun-Soo; Kim, Yeo-Jin; Seo, Young-Rok (December 2015). "An Overview of Carcinogenic Heavy Metal: Molecular Toxicity Mechanism and Prevention". Journal of Cancer Prevention. 20 (4): 232–240. doi:10.15430/JCP.2015.20.4.232. ISSN 2288-3649. PMC 4699750. PMID 26734585.
  17. ^ Järup, Lars (1 December 2003). "Hazards of heavy metal contamination". British Medical Bulletin. 68 (1): 167–182. doi:10.1093/bmb/ldg032. ISSN 0007-1420. PMID 14757716.
  18. ^ "Cadmium (EHC 134, 1992)". InChem. IPCS. Retrieved 5 December 2018.

Further reading

  • Fiedler, I.; Bayard, M. A. (1986). "Cadmium Yellows, Oranges and Reds". In Feller, R. L. (ed.). Artists' Pigments: A handbook of their history and characteristics. 1. Oxford University Press. p. 65–108. ISBN 9780894680861.

External links

Bismuth

Bismuth is a chemical element with the symbol Bi and atomic number 83. It is a pentavalent post-transition metal and one of the pnictogens with chemical properties resembling its lighter homologs arsenic and antimony. Elemental bismuth may occur naturally, although its sulfide and oxide form important commercial ores. The free element is 86% as dense as lead. It is a brittle metal with a silvery white color when freshly produced, but surface oxidation can give it a pink tinge. Bismuth is the most naturally diamagnetic element, and has one of the lowest values of thermal conductivity among metals.

Bismuth was long considered the element with the highest atomic mass that is stable, but in 2003 it was discovered to be extremely weakly radioactive: its only primordial isotope, bismuth-209, decays via alpha decay with a half-life more than a billion times the estimated age of the universe. Because of its tremendously long half-life, bismuth may still be considered stable for almost all purposes.Bismuth metal has been known since ancient times, although it was often confused with lead and tin, which share some physical properties. The etymology is uncertain, but possibly comes from Arabic bi ismid, meaning having the properties of antimony or the German words weiße Masse or Wismuth ("white mass"), translated in the mid-sixteenth century to New Latin bisemutum.Bismuth compounds account for about half the production of bismuth. They are used in cosmetics, pigments, and a few pharmaceuticals, notably bismuth subsalicylate, used to treat diarrhea. Bismuth's unusual propensity to expand as it solidifies is responsible for some of its uses, such as in casting of printing type. Bismuth has unusually low toxicity for a heavy metal. As the toxicity of lead has become more apparent in recent years, there is an increasing use of bismuth alloys (presently about a third of bismuth production) as a replacement for lead.

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 its compounds, and like mercury, it has a lower melting point than the transition metals in groups 3 through 11. Cadmium and its congeners in group 12 are often not considered transition metals, in that they do not have partly filled d or f electron shells in the elemental or common oxidation states. The average concentration of cadmium in Earth's crust is between 0.1 and 0.5 parts per million (ppm). It was discovered in 1817 simultaneously by Stromeyer and Hermann, both in Germany, as an impurity in zinc carbonate.

Cadmium occurs as a minor component in most zinc ores and is a byproduct of zinc production. Cadmium was used for a long time as a corrosion-resistant plating on steel, and cadmium compounds are used as red, orange and yellow pigments, to color glass, and to stabilize plastic. Cadmium use is generally decreasing because it is toxic (it is specifically listed in the European Restriction of Hazardous Substances) and nickel-cadmium batteries have been replaced with nickel-metal hydride and lithium-ion batteries. One of its few new uses is cadmium telluride solar panels.

Although cadmium has no known biological function in higher organisms, a cadmium-dependent carbonic anhydrase has been found in marine diatoms.

Cadmium poisoning

Cadmium is a naturally occurring toxic heavy metal with common exposure in industrial workplaces, plant soils, and from smoking. Due to its low permissible exposure in humans, overexposure may occur even in situations where trace quantities of cadmium are found. Cadmium is used extensively in electroplating, although the nature of the operation does not generally lead to overexposure. Cadmium is also found in some industrial paints and may represent a hazard when sprayed. Operations involving removal of cadmium paints by scraping or blasting may pose a significant hazard. The primary use of cadmium is in the manufacturing of NiCd rechargeable batteries. The primary source for cadmium is as a byproduct of refining zinc metal. Exposures to cadmium are addressed in specific standards for the general industry, shipyard employment, the construction industry, and the agricultural industry.

Group 12 element

Group 12, by modern IUPAC numbering, is a group of chemical elements in the periodic table. It includes zinc (Zn), cadmium (Cd) and mercury (Hg). The further inclusion of copernicium (Cn) in group 12 is supported by recent experiments on individual copernicium atoms. Formerly this group was named IIB (pronounced as "group two B", as the "II" is a Roman numeral) by CAS and old IUPAC system.The three group 12 elements that occur naturally are zinc, cadmium and mercury. They are all widely used in electric and electronic applications, as well as in various alloys. The first two members of the group share similar properties as they are solid metals under standard conditions. Mercury is the only metal that is a liquid at room temperature. While zinc is very important in the biochemistry of living organisms, cadmium and mercury are both highly toxic. As copernicium does not occur in nature, it has to be synthesized in the laboratory.

List of inorganic pigments

The following list includes commercially or artistically important inorganic pigments of natural and synthetic origin.

Oil paint

Oil paint is a type of slow-drying paint that consists of particles of pigment suspended in a drying oil, commonly linseed oil. The viscosity of the paint may be modified by the addition of a solvent such as turpentine or white spirit, and varnish may be added to increase the glossiness of the dried oil paint film. Oil paints have been used in Europe since the 12th century for simple decoration, but were not widely adopted as an artistic medium until the early 15th century. Common modern applications of oil paint are in finishing and protection of wood in buildings and exposed metal structures such as ships and bridges. Its hard-wearing properties and luminous colors make it desirable for both interior and exterior use on wood and metal. Due to its slow-drying properties, it has recently been used in paint-on-glass animation. Thickness of coat has considerable bearing on time required for drying: thin coats of oil paint dry relatively quickly.

Pastel

A pastel (UK: , US: ) is an art medium in the form of a stick, consisting of pure powdered pigment and a binder. The pigments used in pastels are the same as those used to produce all colored art media, including oil paints; the binder is of a neutral hue and low saturation. The color effect of pastels is closer to the natural dry pigments than that of any other process.Pastels have been used by artists since the Renaissance, and gained considerable popularity in the 18th century, when a number of notable artists made pastel their primary medium.

An artwork made using pastels is called a pastel (or a pastel drawing or pastel painting). Pastel used as a verb means to produce an artwork with pastels; as an adjective it means pale in color.

Pigment

A pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light. Most materials selectively absorb certain wavelengths of light. Materials that humans have chosen and developed for use as pigments usually have special properties that make them useful for coloring other materials. A pigment must have a high tinting strength relative to the materials it colors. It must be stable in solid form at ambient temperatures.

For industrial applications, as well as in the arts, permanence and stability are desirable properties. Pigments that are not permanent are called fugitive. Fugitive pigments fade over time, or with exposure to light, while some eventually blacken. Pigments are used for coloring paint, ink, plastic, fabric, cosmetics, food, and other materials. Most pigments used in manufacturing and the visual arts are dry colorants, usually ground into a fine powder. For use in paint, this powder is added to a binder (or vehicle), a relatively neutral or colorless material that suspends the pigment and gives the paint its adhesion. A distinction is usually made between a pigment, which is insoluble in its vehicle (resulting in a suspension), and a dye, which either is itself a liquid or is soluble in its vehicle (resulting in a solution). A colorant can act as either a pigment or a dye depending on the vehicle involved. In some cases, a pigment can be manufactured from a dye by precipitating a soluble dye with a metallic salt. The resulting pigment is called a lake pigment. The term biological pigment is used for all colored substances independent of their solubility.In 2006, around 7.4 million tons of inorganic, organic and special pigments were marketed worldwide. Asia has the highest rate on a quantity basis followed by Europe and North America. The global demand on pigments was roughly US$20.5 billion in 2009.

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