Metal finishing Q&As since 1989

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Can chrome plated plastic form a layer of Chrome 6 over time?

July 3, 2008

First of all I would like to compliment the very good work offered through this website. Personally I have found invaluable information countless times. But this is one of those times when I need to raise a new topic. We have been getting plastic chrome plated parts to be used in interior automotive components for some time now. The question I have been pondering upon is if such chrome plating undergoes chemical changes through time. If any chemical changes occur is there any possibility that a layer of Chrome 6 can form by time?

As always, thank you in advance for your helpful comments.

Regards

Daniel Borg
Engineering Support (Product Design) - Automotive Industry - Imriehel (Qormi), Malta

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July 3, 2008

Hi, Daniel. Thanks for the kind words. Decorative chrome must be very well rinsed to offer an attractive finish, so you can be confident that there is no hex chrome on it at the time of shipment.

1). I have never seen chrome metal convert to hex chrome and that distinct yellow-orange color.
2). Although it's only a few millionths of an inch think I have seen that it doesn't lose it's protective and aesthetic value even in some years of severe exposure use, so I'd say it remains metallic.
3). I don't understand where the oxidizing power would come from to raise it to hexavalent form.
4). And I've never heard of it happening.

So, in total, I'd say it doesn't happen.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey