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Encyclopedia > Cadmium pigments

About 65% to 75% of cadmium produced worldwide is used in the production of Ni-Cd Batteries. About half the remaining consumption, or 2,000 tons annually, is used to produce colored cadmium pigments. The principal pigments are a family of yellow/orange/red cadmium sulfides and sulfoselenides. Brilliantly colored, with good permanence and tinting power, Cadmium Yellow, Cadmium Orange, and Cadmium Red are familiar artist colors, but of little use in architectural paints. Their greatest use is in the coloring of plastics and specialty paints which must resist processing or service temperatures up to 300°C. 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. Cadmium pigments can also color glass and ceramic glazes, not by solution, but colloidal dispersion within the glass. The lenses of red stoplights use this technique. General Name, Symbol, Number cadmium, Cd, 48 Chemical series transition metals Group, Period, Block 12, 5, d Appearance silvery gray metallic Atomic mass 112. ... From top to bottom â€” Gumstick, AA, and AAA nickel-cadmium (NiCd) batteries. ... The term sulfide (sulphide in British) refers to several types of chemical compounds containing sulfur in its lowest oxidation number of -2. ... It has been suggested that Dutch process paint be merged into this article or section. ... Plastic covers a range of synthetic or semisynthetic polymerization products. ...


Cadmium sulfide and a mixture of cadmium sulfide with cadmium selenide are commonly used as pigments in artist's paints. They have an excellent reputation for color permanence although this is partially based on two reasons which are not necessarily directly related to their properties:

  1. when introduced, there were hardly any stable pigments in the yellow to red range, especially orange and bright red was very troublesome, when the cadmium pigments replaced e.g. mercury sulfide (the original vermilion), the light-fastness was greatly improved,
  2. companies sell the cadmium-containing paints at premium price. Although the pigments are certainly more expensive, the premium price is often not fully justifiable, with reasons more in the marketing area then in the actual raw material cost.

Nowadays, the cadmium pigments have been partially replaced by azo pigments. These are similar in lightfastness to the cadmium colors and have the advantage of both being cheaper and non-toxic. With respect to lightfastness the lemon yellow cadmium pigment is an exception: the azo-variety is highly superior in light-fastness. Vermilion, also spelled vermillion, when found naturally-occuring, is often a reddish orange pigment, used since antiquity, originally derived from the powdered mineral cinnabar. ... Azo pigments are solid, colorless particles (typically earths or clays), which have been colored using an azo compound. ...


In some countries, such as Australia, consumer activists such as Michael Vernon were successful in banning the use of cadmium pigments in plastics that could be used for toy manufacture, owing to the toxicity of cadmium. Michael J Vernon AM c1980 Michael Mike Vernon A.M. (2 April 1932 – 6 November 1993) was a prominent Australian consumer activist. ...


Image:Cadmium_orange.png Image File history File links Cadmium_orange. ...


External links

  • National Pollutant Inventory - Cadmium and compounds

  Results from FactBites:
 
Cadmium pigments - Wikipedia, the free encyclopedia (393 words)
The principal pigments are a family of yellow/orange/red cadmium sulfides and sulfoselenides.
Cadmium sulfide and a mixture of cadmium sulfide with cadmium selenide are commonly used as pigments in artist's paints.
With respect to lightfastness the lemon yellow cadmium pigment is an exception: the azo-variety is highly superior in light-fastness.
Cadmium pigments are green ! (897 words)
Cadmium pigments are extremely insoluble compounds of calcined cadmium zinc sulphide (green-shade yellows to golden yellows) and cadmium sulphoselenide (yellow through oranges and reds to deep maroons).
Pigmented plastics in landfills are probably the safest form of cadmium in the environment, even when compared with naturally occurring metal ores.
Scandinavian countries have legislated to force substitution of cadmium pigments using alternatives, and the EU is currently endeavouring to harmonise the legislation in the EU.
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