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Thread: Chrome Plating Aluminum?

  1. #1
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    Default Chrome Plating Aluminum?

    Anyone have any experience or advice on Chrome Plating Aluminum?
    ed

  2. #2
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    I've had lots of aluminum parts chrome plated.
    The material was 6061-T6.
    Just like any coating/plating process the quality of the end is dependant on the start.

    Sid

  3. #3
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    Aluminum can be chrome plated but not directly. It requires intemediate (copper?) plating which is then chrome plated. Chrome plate on aluminum can be a problem because of the difference in linear expansion with temperature. It may detach or flake off.
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  4. #4
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    Quote Originally Posted by Evan
    ... It may detach or flake off.
    Just ask anyone that owned a set of Cragar wheels.

  5. #5
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    Quote Originally Posted by gr8life
    Anyone have any experience or advice on Chrome Plating Aluminum?
    ed
    I heard somewhere that it is really hard to locate a chrome shop that will do it these days. Most will not fool with it because of the problems involved........ pg

  6. #6
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    Quote Originally Posted by Evan
    Aluminum can be chrome plated but not directly.
    -Actually, almost nothing is chrome-plated "directly". Chrome is virtually always applied over nickel; the nickel being the equivalent of the "paint", and the chrome essentially the "clear coat".

    "Triple chrome", as the old hot rodders put it, was copper (which was basically a "filler" for small scratches and pits) then the nickel (which was the main component, and gave the plating the majority of it's mechanical properties) and then the chrome (which acted as basically a "seal" coat and gave the nickel a more bluish-white lustre.)

    But the part about flaking is spot-on. The rate of expansion of aluminum is considerably more than the nickel, and when compounded by the relatively poor mechanical bond between the two, means flaking isn't so much a matter of if, but when.

    For cosmetic items that won't be handled much, it's not a problem. For something that'll see use, and potentially a nick or scratch in the chrome, it's a poor choice, as the plate is virtually guaranteed to start flaking whereever the plating is compromised. High humidity speeds this up, as the aluminum oxidizes under the plating and lifts it off.

    What's the part? Clear anodizing isn't anywhere near as shiny and lustrous as chrome (or even polished nickel) but it's not bad, and both cheaper to do and considerably more durable.

    Doc.
    Doc's Machine. (Probably not what you expect.)

  7. #7
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    Ok. I need to make 2 shaving brush & razor holders. They need to be finished in chrome. Alum. was just a passing idea. Which metal plates best?
    ed

  8. #8
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    Quote Originally Posted by piniongear
    I heard somewhere that it is really hard to locate a chrome shop that will do it these days. Most will not fool with it because of the problems involved.
    -It's not the problems, it's the chemicals. Heavy metals (nickel and chromium) baths of dilute sulfuric acid, evolved acid vapors, etc.

    There's still plenty of shops that domit, but not nearly as many as they used to be back in the 70s.

    There's exactly one in the entire state of Alaska- the guy's been running it since 1975, and has only been able to keep going for the last ten years thanks to being grandfathered in. He wants to sell the shop, but there's absolutely no way- a new owner would have to bring the (somewhat dilapidated) old shop up to modern specs (Federal regs if nothing else) and that would involve essentially jacking up the sign and rolling a complete new building under it.

    Once he goes or decides to retire, we'll have to send parts to California to get 'em plated.

    Doc.
    Doc's Machine. (Probably not what you expect.)

  9. #9
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    Quote Originally Posted by gr8life
    Ok. I need to make 2 shaving brush & razor holders. They need to be finished in chrome. Alum. was just a passing idea. Which metal plates best?
    -Steel and brass, in that order. Steel can be electroless nickel plated, and that's something of a savings in some shops (easier and cheaper to do.) Brass can be as well, but has to be essentially "catalyzed" to start plating. It works fine, but the plate "sticks" best to steel.

    Doc.
    Doc's Machine. (Probably not what you expect.)

  10. #10
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    Why does it have to be chrome??? Aluminum will polish up as bright as chrome.
    Ernie (VE7ERN)

    May the wind be always at your back

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