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A portion of part did not get chrome plated

November 8, 2009

I plated a trapezoid part inside.the size of the part is 20 in. long and 18 in. long.
I built a lead and antimony anode. I got a strip along the part that wasn't plated.
what can I do to avoid this strip ?

Yaniv Rodity
I work in a company that plates - Israel

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Hi, Yaniv. A photo might help because I can't quite picture the situation. If the area that did not get plated was further from the anode, this is not strange or unexpected because chrome does not deposit at all if the current density is too low.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
November 8, 2009

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You give no details of your process - are you using hexavalent or trivalent chromium? What current are you applying and is it full wave rectified? What chromium bath are you using and is it in spec? So many questions to be answered...
My guess is that the length of the anode is too great and that you are getting areas of low current density. This can be overcome by making sure you have enough current applied for good chromium plating and that you make anode, and cathode connections at regular intervals down the length of the electrodes.

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
November 18, 2009