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world gathers for metal finishing
Q&As since 1989


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Aux. anodes, titanium, robbers and such

2004

Hello all:

I would like to ask for some advise from the forum. Trevor has addressed a similar questions in the past but I would like more input.....more is better! (sometimes) I am going to be plating (watts nickel/hex chrome) a polished aluminum intake manifold for a small block motor. Its new with no grease in its pores. I will be plugging the internals and masking the carb/head mount points. My question/problem is getting the nickel and chrome into the recessed/LCD areas. I have used plastic shields extensively in the past but the manifold doesn't seem to lend itself to this set up. Honesty....I can't afford platinized anodes either! If I use titanium aux. anodes for 50 minutes in the watts nickel bath do you think they will go passive and then lead to no throw when I transfer to the chrome? I don't want to have to strip the chrome on this manifold as I know the LCD areas will blister from the hydrochloric acid. Then were into the copper! I can make aux anodes out of nickel and lead but that leads to a switch over after the nickel...and passivation of the nickel...reactivate...you know...just a pain. Does anyone have any other suggestions I'm not aware of? I appreciate your input as you guys have a heck of a lot more experience then I.

Thanks!

Tom Haltmeyer
- Peoria, Arizona, USA!

Why not considering electroless nickel as your final plate? It is well suited for aluminum and there are formulations that produce very bright finishes. Certainly, an aluminum motor manifold is not a part any chrome plater would like to plate no matter how experienced he is.

Guillermo Marrufo
Monterrey, NL, Mexico
2004

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2004

Guillermo:

Thank you for the reply. I'm not set up for electroless and I believe it would eventually tarnish in time (yellow). Thats why he wants it finished out in chrome. Although the even throw of electroless would be great. As with anything...the hot rod guys here in the states are continually trying to outdo the other and look better then the other. The last car this guy built is appraised at $185,000. So, they will do anything to look better. Heck! my last car was only 1500 bucks! The manifold will definitely be a challenge. But thats how we get better! :)

Tom Haltmeyer
- Peoria, Arizona

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I would be a bit concerned about thermal cycling of aluminium manifolds as you may risk getting de-bonding of the coating from the manifold. You must make sure you get excellent adhesion.

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
2004

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Chromium plates well over electroless nickel and the covering/throwing power of chrome is improved over plated bright nickel

Don Baudrand
Consultant - Poulsbo, Washington
(Don is co-author of "Plating on Plastics" [on Amazon or AbeBooks affil links]
           and "Plating ABS Plastics" [on Amazon or eBay or AbeBooks affil links])
2004

No electroless available... whatsoever. Not even as a safety underplate in case you need to strip (or you just don't want a colleague to put his hands over your job? OK, I understand). Let see if this helps: graphite anodes (no metallic additives). Impossible to bend, porous and will not bring Cr3 back to Cr6. Hmmm...? But they will not passivate no matter what you do to them, and are way cheaper than platinized Ti.

Guillermo Marrufo
Monterrey, NL, Mexico
2004

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Thanks for the replies. We pretty much decided to go with just polishing the manifold and timing chain cover.(Thanks Trevor) The water pump will be plated though. don't want to take a chance on peeling down the road. Thanks for the info all I will be using graphite for the water pump plating.

Tom H. (still in business!:)

Tom Haltmeyer
- Peoria, Arizona, USA
2004