Chromium VI
Required limit value:
Should not be present in products.
CAS RN:
Chromium VI (Cr+6, hexavalent chromium): 18540-29-9
Properties:
Dangerous for the environment. Carcinogenic. Allergenic. Toxic.
Use:
Metal plated metal parts. Chromic acid is used as wood preservative. Some dyes may contain chromium. Oxidation agent. Fixing chemical. Used for finishing of direct dyes to improve their wash fastness. Potassium dichromate is used for oxidation of vat and sulphur dyes. Chromium salts are used for preparation and finishing of acid dyes on silk and wool. Tanning leather with basic chromium III salts is the most widely used method where chromium VI may occur as an impurity. Etching of artificial leather and rubber.
Comments:
Chromium III is an alternative in surface treatment of metal but only for decorative metal plating and not hard metal plating. Other metals such as tin and zinc may be used for metal plating instead of chromium VI. Chromium III is an alternative as fixing agent in mordant dyeing. Use acid dyes with high colourfastness to avoid use of chromium salts for dyeing of polyamide, silk, wool and leather. Use hydrogen peroxide and other per-salts to avoid the use of chromium VI-based salts. In leather tanning chromium III is used, but can oxidize to chromium VI under uncontrolled conditions. Vegetable tanning agents are alternatives for leather if these tanning agents are formaldehyde free. Tanning with titanium is an emerging technology. Common chromium VI substances are listed in Annex 5.
CHEMICALS GUIDANCE | Edition: January 2020 | © 2020 Textilimportörerna/Swedish Chemicals Group - RISE IVF
37
