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Aluminium Anodizing

Discussion in 'Fit & Finish' started by Chris Roy, Feb 29, 2016.

  1. Chris Roy

    Chris Roy Active Member

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    Wondering if anyone has messed around with anodizing aluminium with dye. Iv'e tried some here in the shop the last few days, a few different ways and not getting good results at all. Wondering if anyone has tried this and could lend some advice.
     
  2. Yamroll

    Yamroll New Member

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    Probably will need some more details. What voltage and current are you using? What dyes? What electrolyte? What kind of results are you getting? It's hard to know what to fix without that info!

    I could see the following things being problematic:
    -Inadequate degreasing/deoxydizing
    -Inadequate anodizing current
    -Dye solution too hot
    -Bad electrolyte
     
  3. Chris Roy

    Chris Roy Active Member

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    I watched this video . Followed what he did at 10 amps (tried a number of different times from 30 mins to 2 hours) Couldn't find any battery acid in town but i found some concentrated sulfuric acid drain opener that i used for the electrolyte. Had the acid bath between 50 to 70F. Dye was between 110-140F. Made sure to clean all the parts multiple times. Not really sure what the problem is being a multiple step process. My cathode and anode are both 6061 aluminium. Not sure about the wire i'm using to hang them. Says aluminium but not sure what type.
    [​IMG] the tank set up. This was the first night. added some cooler packs to try and keep the temp of the bath below 70F.

    [​IMG] was supposed to be a dark green and barely took in any dye. Few other attempts were even worse. As soon as i went to seal them all the dye came off.
     
  4. dancom

    dancom Dust Maker Best Shop Tool

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    I've only experimented with this before. My guess is that the layer of aluminum oxide is too thin. It could be the acid concentration is too strong and actually dissolving the oxide layer while it's being created, or the was insufficient current/time in the anodizing bath to build up the oxide layer. I don't know how one would measure the thickness of the layer, but I feel that using a known acid concentration would be a place to start the troubleshooting.

    Dan
     
  5. Yamroll

    Yamroll New Member

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    Yeah, a thin oxide layer would do it.

    In some cases, depending on how different the wire and part alloys are, the wire will be anodized rather than the part. You could experiment with different wires, or go afield to get wire known to be the same alloy.

    Did you de-grease and de-oxidize the part before the anodizing? That could be it as well. Aluminum will form an oxide layer slightly different than the anodized one on it's own and can prevent the formation of the desired oxide. A rinse of isopropyl alcohol followed by a lye bath would do the trick.

    Admittedly, it's been years since I've tried this, so I'm a little foggy on details. I'll have to ask my girlfriend when she gets back to town, she did some anodizing in her college days.
     
  6. John Noon

    John Noon Well-Known Member

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    Also the aluminum will have to be anodized immediately after cleaning / acid bath, the new oxide layer forms within 20 minutes.

    I did a quick search and there are several guides that will help solve your problems. Looks like the wiping off of the anodize is from lack of cleaning in the acid bath.

    search for "anodize troubleshooting guide"
     
    Last edited: Mar 1, 2016
  7. Chris Roy

    Chris Roy Active Member

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    Thanks for the input guys. I got the msds of the drain opener today and believe my bath was way too concentrated. I'll try the new mix first and see what happens.

    Ya i'll try a few different wires and see what happens.
    I washed with soap and water like 6-7 times with a toothbrush. Did a water test that i saw online. no beading = clean from what i read. Might have to try and find some lye.
     
  8. Yamroll

    Yamroll New Member

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    Before you go out and try new wire, I'd try the lye. Sounds like you decreased well enough, but remaining aluminium oxide could still be an issue.

    I'd also try the dye and sealing on the wire you have after the anodizing, as well. If that's the issue, it should accept the dye pretty readily.
     
  9. John Noon

    John Noon Well-Known Member

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    No beading is clean but all the oxide should be removed by acid bath or mechanical means.
     

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