Cracks in brush plated copper

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I got a couple of responses about copper brush plating kits and thought I should get some more info. We have a couple of copper jobs (OFHC copper), which have developed cracks in their electron beam welds. The cracks are about 1 millimeter wide, 1 mm deep and 2-3 mm long. These need to be filled with copper. That implies plating copper on copper. NOT for strengthening purposes. The finish has to be almost mirror finish. In a couple of jobs the cracks are deeper 3-4 mm deep - can brush plating fill deeper cracks? In some cases the cracks are a bit inaccessible - at the end of a 600 mm long, 200 mm dia cylinder. Any opinions/views and of course quotes (with details) of brush plating kits are welcome.

Dr. Nitin Thakur
Australian National University

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From the information you have given, I can say that you can brush plate these cracks.With a one to one aspect ratio of the cracks, it makes for a little more difficult repair. First you need to open up the cracks with a small grinder. A Dremel tool works fine. You need to do this because you would be using a acid copper solution which does not have very good throwing power. It would have a tendency to bridge over the crack top. After you dished out the crack(at least ten to one)then you can plate. You need to mask off the repair area by approx. 1/16 inch around the crack.After you are finished plating, you must dress back to the original surface. Again you can use the Dremel with various attachments to do this. As to a final polish,use the Dremel with a polishing point to polish to the desired final surface finish. There are more questions that need to be answered before I can say what exactly you need to accomplish this. As far as a kit goes, for your application a simple kit would suffice.

Tom Sivula
plating shop - Harbor City, California