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Preventing nickel allergy using various topcoats for decorative items

New research carried out by Nickel Institute consultant Clive Whittington and Dr W. Y. Lo (Secretary General, Hong Kong Surface Finishing Society) tested a range of coatings over nickel-based decorative articles such as costume jewellery and watches, to prevent nickel allergic contact dermatitis (NACD). The aim of these coatings is to keep the concentration of nickel comfortably under the REACH (the EU Commission’s Regulation on Registration, Evaluation, Authorisation and Restriction of Chemicals) safety restrictions and thus minimise the risk of nickel allergy. Nickel-containing decorative alloys were also evaluated.

The study published by found that regular hexavalent chromium, microporous trivalent chromium from a chloride electrolyte, ultraviolet (UV) cured polyurethane electrophoretic coatings and an electrodeposited palladium barrier all prevent nickel release. Nickel-containing stainless steel with or without a PVD TiN coating readily passed the CEN nickel release tests. The results of this work mean these coatings and alloys can be used for decorative articles that are sold in the market without concerns about nickel release exceeding the recommended limits.

Download the paper here

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