Inexpensive black electroplate technique?

Letter 3094

Inexpensive black electroplate technique?

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I have several dozen 1/2" diameter bolts, washers, and nuts that I would like to have 'plated' black. These are the type that one would buy at a typical Home Depot hardware store. I am not sure of the exact type of electro-plating that these have, I think it might be nickle-cadmium (please correct me if I am wrong). Knowing how expensive it is to have these plated 'black oxide' by a professional company, I was wondering if someone could recommend a relatively inexpensive way that I could do this at my home. Is there any type of home electro-plating electrolyte I can purchase that will plate a blackish color directly on top of the existing finish? Or must the nickle-cadmium finish be first removed? I have a 20 amp 12 VDC power supply at my disposal.

greg a
- san diego, ca

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Full name next time please, Greg.

You would be better off going to a specialty hardware supplier and buying the fasteners you need with the black oxide finish already on them. The problem is that such parts are plated or black oxided in bulk (by the thousands), adding little to the cost of the fastener at time of manufacture; but it is very labor intensive (and consequently quite costly) to finish them a few at a time on a rework basis.

If you have to do something yourself, I'd very lightly sand them to remove most of the chromate, then paint the exposed surfaces black.

BTW, it is unlikely that the finish is nickel-cadmium, that is usually reserved for aircraft components; fasteners from Home Depot are almost surely zinc plated and chromated.

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

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