28 октября, 2015 
Pokraskin International, technical specifications for chromium oxide pigments are defined in ISO 4621 (1986), they must have a minimum Cr2O3 content of 96 wt.%.
Various grades are defined according to their particle fineness as measured by the residue on a 45 pm sieve: grade 1, 0.01% residue (max.); grade 2, 0.1% (max.); and grade 3, 0.5% (max.).
ISO 4621 (1986) also specifies analytical methods. Usually, analysis of chromium and the byproducts is preceded by melting with soda and sodium peroxide. The content of water-soluble or acid-soluble chromium is becoming important from the toxicological and ecological point of view. It is determined according to DIN 53780 with water, or according to ISO 385615 with 0.1 mol L-1 hydrochloric acid.
3.1.2.4
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