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Are chrome plated goods safe under European Directive?

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article image Chrome conversion coatings

“The European RoHS (Restriction of Hazardous Substances) and ELVD (End of Life Vehicle Directive) directives have caused a certain amount of confusion among manufacturers in relation to chrome plated goods” says Amanda Wood, Managing Director of A-Class Metal Finishers, Lonsdale SA.

“It is often thought that because something is chrome plated it is RoHS or ELVD) restricted but this is not necessarily the case.”

The European RoHS directive restricts the presence of certain hazardous substances in electrical and electronic equipment.

Similarly, the ELVD places restrictions in automotive applications. These directives affect goods made, or sold into, European markets and are also impacting on other markets around the world.

Any Australian manufacturer or supplier in these supply chains would by now be well aware of these directives which restrict the use of substances.

Australian Manufacturers also need to be aware there is apparently a report expected to be released soon from the Federal Department of the Environment and Water Resources which discusses Australia’s adoption of the European RoHS (or similar) standard.

China and other Asian countries have, or are forming, similar directives or laws too.

There is a lot more to these directives than can be discussed here and companies should seek to confirm the finer details for themselves but basically, the directives seek to restrict certain hazardous substances (such as lead, cadmium, mercury and of course chromium VI, otherwise known as hexavalent chrome) from creating exposure hazards in their useful life as well as at end of life, when disposed of as waste.

The process for achieving a standard decorative chrome finish (such as you would find on your car trim, or bathroom taps) is usually hexavalent chrome plating (or increasingly, trivalent chrome).

However it is only in the processing stage that the item is exposed to the hexavalent substance.

Once the plating process is complete, the item has a surface of hard chromium metal but in this form it has no valence or is essentially inert.

In the plated state, or in the process of breaking down over time, the item is therefore not likely to leach hexavalent chrome into the environment because the hexavalent material is simply not present in the article (other than possibly in minute traces within RoHS limits).

Contrast this however with, for example, chromate conversion coatings and the situation is different.

Chromate conversion coatings do not result in an inert metal surface but rather, a barrier of hexavalent and or trivalent chrome, which protects the item from corroding.

This barrier is softer than chromium metal and over time chrome VI can leach from those coatings. The RoHS guidelines allow only up to 0.1% of total item weight of restricted substances to be present.

Technology advancements are getting closer to providing hexavalent chrome free processing (there are a number of safer tri-valent processes available) some do not as yet match up to the quality and performance of other coatings but several good alternatives are available.

So, in summary, if a manufacturer is using decorative or hard chrome plating for its products, from the product point of view there is no need to be concerned about hexavalent chrome exposure in the product’s lifetime but where chromate conversion coatings like zinc chromates are used there are some concerns so manufacturers should seek further information or look to alternative coatings (for example electro-less nickel plating, electrophoretic coating, paint or trivalent chrome processes).

Some of the alternatives may be slightly more expensive but may also offer additional advantages.

A Class Metal Finishers  provide guidance on all types of surface coating and finishing issues.

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