Substandard powder coating ... now what can I do? | FerrariChat
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Substandard powder coating ... now what can I do?

Discussion in 'Technical Q&A' started by dave80gtsi, Jun 16, 2005.

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  1. dave80gtsi

    dave80gtsi Formula 3
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    Nov 3, 2003
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    Dave Meredith
    #1 dave80gtsi, Jun 16, 2005
    Last edited by a moderator: Sep 7, 2017
    Opinions, please.

    You may recall that I started a thread here about a week ago concerning the pros and cons of powder coating magnesium wheels. This was because I had been receiving vague warnings from the coater about the possibility of problems inherent with coating magnesium.

    Background: About 18 months ago I had my OEM set of 7-1/2" x 14" magnesium alloys bead blasted to clean, and then powder coated silver. I have been really pleased with the results - see enclosed "mounted" picture. So, when the current coater mentioned his concerns, I tended to dismiss them since I had proof that these coated mag wheels could turn out good.

    Well, this afternoon the coater returned my set of magnesium 7" and 8" x 16" QV wheels which I had delivered to him blast cleaned, as before, and the last three (3) pictures (the unmounted ones) are how they turned out. Big difference compared to the older 14" ones, as you can see.

    My first inclination is to have the powder coater set them right, but I am apprehensive about just what that might mean. My initial thought was that they needed to be re-blasted to remove the new wrinkled powder coating and then start over, but since powder coating is so tenacious, I am concerned that the act of blasting them clean will damage their face. So, perhaps they could instead be chemically dipped, but again, will the powder coating come off readily without damage?

    Or, do I simply figure that this is one of those lessons learned, live with it, and move on? The coater did the work inexpensively as a professional courtesy (he does a ton of "official" work for our company), so I am hesitant to rake him over the coals on this one. He did "warn" me of the results, but I now tend to think that this was just a C.Y.A. move on his part, just in case I was not happy (an excuse for his poor workmanship, perhaps?). But, at the end of the day, I am left with what I consider to be sub-standard work!

    Any thoughts? Cheers - DM
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  2. SRT Mike

    SRT Mike Two Time F1 World Champ

    Oct 31, 2003
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    #2 SRT Mike, Jun 16, 2005
    Sorry to hear about your problem.

    First off, the wheels can be plastic media blasted. This will remove the powdercoating but will not affect the underlying metal. It will not roughen or smoothen the metal, only remove the powdercoat. So yes, you can get back to where you were before powdercoating.

    Now, on the actual coating. I suspect the shop did not correctly prep the parts. You're not supposed to just powdercoat magnesium bare, because it has problems sticking. The fact that this guy "warned" you, makes me think he doesnt have the correct tools to do the job. I think if you go back to him, he will probably not be able to do any better a subsequent time than he did the first time.

    There is an alkaline chromate dip you can use on the wheels which will prevent powdercoat adhesion problems, however the waste from this process is hazardous and must be disposed of correctly (read: $$$). There is an alternative process which usually leaves the part a bit dirty and can cause problems in the finish of the powdercoat. I am guessing your coater either used the second more enviro-friendly process that gives a worse finish, or he did no surface prep and this is the result.

    Everything from magnesium laptops, cell phones, wheels, interior automotive parts and many other things are made from magnesium nowadays, so powdercoating magnesium is not the issue... the issue is the way in which your guy did it. For that reason I would not suggest going back. Either he is not knowledgeable about how to coat Mg, in which case you don't want him doing it, or he is knowledgeable about coating Mg, in which case he saw your rims looked like **** and decided to give 'em back to you anyway, which speaks badly about his version of "quality". Either way I'd go elsewhere. Actually I'd leave 'em as is and let the new coater strip the stuff off so he can see what you DON'T want. Set expectations up front and that way if it comes out badly, it doesn't turn into a he-said-she-said type thing.

    Hope it helps.
     
  3. dave80gtsi

    dave80gtsi Formula 3
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    #3 dave80gtsi, Jun 17, 2005
    Mike - Thanks much for the info. Your comments are well reasoned and insightful.

    I like the basic idea that the coater tried to do a good job but was limited in his 'tools to work with', be that in terms of his apparatus or his knowledge. But I do concur that returning them to him with a request for him to make it right is a bit of a flirt with danger.

    Instead I think I will follow your excellent idea of keeping them as is, and then let another firm see the initial results and determine if they can indeed make it better.

    If you all are intersted in this saga, I can post updates and progress as news develops.

    Cheers - DM
     

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