Letter 26067

Chrome plating of fasteners for motorcycles  

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I have a number of zinc plated fasteners on a motorcycle that I wish to chrome plate. How do I remove the zinc plating on the fasteners? Then I know I must copper plate the fasteners first. I am familiar with using copper sulfate solution to copper plate raw steel after the zinc is removed but I also wish to nickel plate the fasteners after copper plating. I understand there is a solution to nickel plate not involving DC current. Next I want to chrome plate the fasteners. I intend to use chromium trioxide. What is the difference between trivalent chrome plating and hexavalent chrome plating.? Which is better if there is one better? How can I use hexavalent chrome plating which is what I see advertised by companies as if it is superior to trivalent chrome plating.

John Morbius
student - Albany, New York

Hello John. Some people don't realize it, but plating is a jobshop oriented business. What you need to do is to just take your zinc plated fasteners to a plating shop and tell them you want them nickel-chrome plated.

We appreciate your efforts to learn this science, and you might find our Chrome Plating Tutorial interesting. But it would take you months (at least) to learn how to do this, and you would have to use regulated, toxic, carcinogenic chemicals that you probably can't buy, and there is no legal way for you to dispose of the waste products.

Actually copper sulfate plays no part in this process. Electroless nickel is rarely used under decorative chrome, and it isn't as bright as what you are looking for; you want electrolytic nickel plating. Trivalent chromium is for practical purposes impossible for a hobbyist. The imitation hex chromes that are sometimes sold to hobbyists as safer than hexavalent chromium are not tri-chrome, they are usually cobalt-based plating solutions.

Ted Mooney, P.E.  finishing.com Brick, New Jersey

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