December 08, 2015
Nickel is the most technically attractive, economical and durable undercoat for electroplated consumer products. There can be, however, the possibility of those coatings releasing nickel ions and of potential cases of nickel allergy.
The EU has legislation in place to address this issue. Tests for nickel release are governed by standards (EN 12472 and EN 1811) and allow compliant electroplated products to be placed on the market.
For two decades, the Hong Kong Productivity Council has inspected and qualified articles for export to Europe. The Council examines over 500 different consumer products each year to test for conformity with EU regulations.
In a recently published paper, the Council’s researchers tested relevant coatings including advanced electrodeposits, new organic coatings and conventional chromium to ensure bright nickel-chromium electroplated surfaces could be certified without fear of nickel release during, in the words of the EU regulation, “normal handling and use”.
The standout performer was conventional chromium plating with its nickel substrate. It is the least expensive, simplest and most readily available protective coating of nickel, and provides a practical industrial method for the prevention of nickel release from the undercoat.
While this test program focused on bright nickel-chromium deposits, the outcome provides pointers for further examination of other coatings, including the use of satin and black nickel-chromium finishes for automotive components, consumer products and electronic devices, as well as flash coatings of gold over electroplated nickel underlays for costume jewellery. For small articles requiring barrel plating, alloys of tin could be similarly evaluated. But in all cases, the surface finish must provide sufficient abrasion and corrosion resistance to meet the EN nickel release tests.
According to the Council’s researchers, conventional chromium applied according to ISO specifications for plating on plastics or metal substrates will prevent nickel release from the nickel undercoat of decorative electroplated articles and allow manufacturers to provide products that meet the strict EU regulations designed to protect consumers.
This work identifies surface finishing processes that allow electroplated nickel to be incorporated safely into consumer products.
Condensed from “Prevention of nickel release from decorative nickel-chromium electroplated articles in the context of allergic contact dermatitis”, C.M. Whittington et al, Transactions of the Institute of Materials Finishing, vol.93/4, 2015 - read more here.
Download The Nickel Plating Handbook
Appropriate Uses: Not all uses of nickel are appropriate
Sensitivity to nickel was first observed about 90 years ago when workers in electroplating shops complained of skin rashes, presumably because of their contact with nickel chemicals. This became known as “nickel itch”, a benign name for a condition that, depending on the individual, could be much more problematic than an itch implies.
When nickel-plated items became very widespread in every day life and, more importantly, ear piercing and body piercing became more popular, so did sensitivity to nickel. By itself, body piercing is mainly a fashion and cultural choice. But when jewellery items intended for piercings and fashion accessories in direct and prolonged contact with the skin were plated with nickel—or nickel with a soft and porous overlay of gold—the problem of nickel allergy became more common.
Direct and prolonged contact
Societal responses to this vary but the European Union took the lead more than a decade ago with the Nickel Directive. Products placed on the market in the EU and intended for direct and prolonged contact with the skin now have to conform to strict maximum levels of nickel release. Dr Kate Heim, the nickel allergy expert of the Nickel Institute’s health and environment science research arm (NiPERA) said, ”Nickel Institute supports the use of appropriate materials in appropriate applications for many reasons, including avoidance of adverse health effects. If the use involves direct and prolonged contact with the skin, including body piercings, then only appropriate materials should be used to avoid nickel allergic contact dermatitis.”
The Nickel Institute produces publications on NACD and has an active program of collaboration with researchers and regulators to increase scientific knowledge and raise awareness of nickel allergy.