Cadmium pigments are stable, inorganic colouring agents which are produced in a range of rich, vibrant shades of yellow, orange, red, and maroon. Modern day pigments made by our ICdA member companies are carefully engineered products manufactured in regulated chemical plants with full Health and Safety and Environmental permits under Responsible Care management and adherence to ICdA guidance principles. These pigments have a carefully defined and engineered particle size, crystal structure, surface area and surface treatment to ensure they are not only correct for colour but also meet extremely low solubility and other key property limits.
In the EU, Cadmium Pigments of ICdA member companies have undergone EU Risk Assessments and are fully EU-REACH registered. These have concluded no risk to people or the environment and are specifically exempted in the Cd compounds entry 048-001-00-5 of Annex VI to CLP. They are classified as non-hazardous with no requirement for any hazard labelling.
EC Number CAS Number
Cadmium sulfoselenide red 261-218-1* 58339-34-7
(CI Pigment Red 108)
Cadmium sulfoselenide orange 235-758-3* 12656-57-4
(CI Pigment Orange 20)
Cadmium zinc sulphide yellow 232-466-8** 8048-07-5
(CI Pigment Yellow 35)
* For EU-REACH administrative purposes, these entries have been assigned as UVCB (Variable Composition) with hexagonal structure and given an alternative EC number of 701-229-5.
The compositional formula is CdS1-xSex where x=0.001 – 0.25.
** For EU-REACH administrative purposes, this entry has been assigned as UVCB (Variable Composition) with hexagonal structure and given an alternative EC number of 701-227-4.
The compositional formula is Cd1-xZnxS where x=0.001 – 0.46.
The pigment chemistry is based on solid solutions of Cd,Zn, S, Se formed by calcining at high temperature to convert fully to a crystalline and stable hexagonal form, before undergoing a series of further treatments resulting in highly engineered pigment grade products.
Cadmium pigments are versatile colouring agents that possess the following features:
- Excellent and unique full and unbroken yellow-orange-red-maroon colour range with complete inter-mixability to give mid tones;
- Their chemical and physical stability means that they can be mixed with virtually any other pigment to achieve the desired shade;
- Excellent light and weather fastness (including UV);
- Superior heat temperature stability (>400C);
- Excellent opacity with high tinting strength;
- Insoluble in water and organic solvents and no bleeding and no migration;
- Stronger, more intense and have better hiding power;
- Good chemical resistance, especially to detergents, alkalis and those acids used in testing regimes;
- Easily dispersible and able to be mixed with whiteners to give clean opaque shades
These properties make Cd pigments unique. Being difficult to substitute, they are typically the materials of choice for ceramic, glass and metal decoration, plastic colouration and for the professional artist including restoration work.
Cadmium pigments find niche applications in market segments where their unique blend of properties of clean colour shade, intensity, opacity, heat and light resistance and long-term stability are paramount. Typical application areas follow but are not limited to:
Cadmium pigments have inherent high temperature resistance because of their method of manufacture and may therefore be used routinely in polymers which are processed at or above 300ºC e.g. polycarbonate, nylons and PTFE. Further, because of this high temperature resistance, all moulding sprues and off-cuts can be recycled whereas an organic may already be starting to undergo decomposition during moulding and be unable to withstand further heating. In the EU, there are restrictions of use in specified plastics, but are permitted for higher temperature, engineering plastics or where safety indication is the primary function. These restrictions are described in entry 23 of Annex XVII to REACH.
Cadmium pigments have long been the standard against which other pigments are judged by artists. They continue to be the only choice for top-quality oil and water colours requiring stable, clean and opaque products in the yellow-orange-red colour space.
Coil coatings often require high performance pigments due to the nature of their application areas; it is difficult to achieve bright yellows, oranges and reds with the appropriate level of shade, opacity and performance. For this reason, Cadmium pigments are used due to their excellent lightfastness for architectural materials and also due to their heat resistance which makes them eminently suitable for the temperatures that can be reached during the application of this type of coating.
Cadmium pigments are used in thermoplastic and thermosetting powder coatings due to their high performance and heat resistance.
Ceramic, glass and enamels
The colouration of decorative ceramic, glass and enamel products often depends on the use of cadmium pigments. They are the only pigments for bright yellows, oranges and reds which can withstand the firing processes during manufacture and application. During processes such as on-glaze colours, porcelain enamels for steel and glass colours for both flat glass, tumblers and bottles, cadmium pigments will be encapsulated in the glass matrix to meet the demanding requirements of colour and stability.
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The International Cadmium Association (ICdA) is a non-profit association representing the interests of the world’s cadmium industry. Its Members include producers, processors, recyclers and consumers of cadmium metal, cadmium compounds, and products to which cadmium or its compounds have intentionally been added.
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