Chrome plating onto aluminum

A. Hi Tony. Aluminum immediately forms a passive film onto which it is not possible to electroplate. Therefore the first step is to apply a zincate coating.

Once the zincate finish is in place you either start with cyanide copper before acid copper-nickel-chrome plating or start with alkaline electroless nickel plating before copper-nickel-chrome instead. The process vendors will be able to give you reprints of shop write-ups from the trade journals. Good luck,

A. Years ago I was involved in plating aluminum pistons. We double zincated the parts and used Enthone's alkaline EN at a much lower temp than recommended. It has a very strong ammonia ⇦ this on eBay or Amazon [affil links] smell. If you try it, buy a gal of stabilizer because it will plate out in a week or so at Miami ambient temp. They can tell you how to use it and it sure is not in the ops sheet. You might even want to put a layer of regular nickel on it because you will have to re-rack, clean and activate unless you are using tank anodes in your chrome. If you find a way to get all of the chrome off of the racks, please tell me because it always seemed to find a spot that contaminated another tank. It takes some getting used to, but plating on aluminum is not all that bad and the EN strike made it a lot better.

A. I found 2 ways would work on aluminum, one was after double zincate to use EN strike for parts with deep recesses (such as rims). The other was a cyanide copper strike. Both of these were followed by plating the parts in acid copper, then nickel-chrome.

A. Sorry Ben, I'm not really familiar with hydrogen embrittlement of aluminum, but see letter 55684, which addresses the subject in some detail.

Regards,

A. Hi Mike. A photo would probably help because I'm not sure what this 'dust cover' is about, but I would certainly cancel if the shop guesses at 50% success. Plus, the term 'hard chrome' doesn't fit with this application -- meaning that a misunderstanding is involved as well.

It is difficult and tricky to plate onto mixed metal construction like aluminum and brass because the pretreatment process is usually much different, requiring masking and de-masking mid-process. New tuners more to your liking would probably be less expensive.

Regards,

A. Hi. Thanks for the pic. The black chrome plating would probably completely obscure the monogrammed pattern on those dust covers. How about asking the plating shop to mask them before plating, leaving the look of the dust covers exactly as is? They can later get a charcoal tinted clear coat if you wish, which would darken them without hiding the monograms. Although it is possible to clearcoat first, and use the clearcoat as the maskant, I wouldn't chance it on these items. I think it's worth a call to Spector to see if they have replacement tuners, possibly even in black chrome.

Regards,

 Great idea. Thanks!