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  • Anodizing aluminum

    Now I am using that wire to hang just one part of my aluminum. So I am anodizing my part in 12 V 3 A/square dm current density for 45 minutes, the result is the absorbed the dye perfectly but it seems like the part is get burning in some spot. Is the problem the agitation system (cause I am not using agitation yet), too much current density, or too much time of anodizing?
    Here is my anodizing method :
    -. Clean with non-etch cleaner, then rinse
    -. etch in caustic soda for 3 minute, then rinse
    -. anodizing in sulfuric acid with 12 V 3 A power supply for 45 minutes, then rinse
    -. dye in room temperature for 20 minutes, then rinse
    -. seal in cool sealant for 10 minutes, then rinse
    Attached Files

  • #2
    Ok you've already asked these very questions in another thread. If you want to get serious about your inquiries we'll need more info to properly answer them, starting with the strength of your electrolyte (in g/L) without knowing this there is no way to accurately apply a factor for time in the tank let alone amperage. As for agitation, it's an absolute must, without it localised heating will occur burning your parts. Tank temps are also important, starting temps must be within 68f to 72f (20 to 22c) and remain there. The more it climbs the faster it will reach dissolution. Dying parts (as I mentioned in your other thread) is best done at 120f (48c) to acquire maximum dye uptake. You are using a metric calculation for current density which we don't use here so it's only a guess converting it to ASF which is likely not accurate so if you can provide it in ASF that would help.

    If you can provide this info we can help you.

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    • #3
      I am using 1 part of battery acid and 3 part of water so dont know my concentration of acid in exact. I will apply my agitation system soon. my tank temps is within that range and remain there. My current density is 3 A/square dm so it will be 27.870912 ASF.

      Thanks for your help.

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      • #4
        So your tank is approx 12% which is approx 129 g/L. You'll need to add more battery acid to get it to 180g/L but we need to know your total tank volume first. And your part is drawing .27 amps, not 27 amps based on your metric calculation.

        So with that said you are running your system close to the 12ASF method which means you are going to build a coating but it will be sub par at best. In order to correct this you'll need to bump the acid content, get some sort of agitation in the tank and set your amperage side of the power supply to full and slowly ramp up your voltage to 14V and run for 60 minutes. You'll be running in constant voltage so your part size will not matter as it will draw the necessary amps it needs and your outcome will be better.

        Good luck

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        • #5
          how to calculate my concentration acid is approx 12% and 129g/L?
          is using aerator can fix the agitation problem (I cant find pump that doesn have metal part in the water and acid resistant yet)?

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          • #6
            Originally posted by faprialdi View Post
            how to calculate my concentration acid is approx 12% and 129g/L?
            Most battery acid is around 30% or 1.25 SG so a simple calculation of dilution will bring you to the number I calculated. It can then be converted to g/L to get you into range. If you have a battery tester with a small glass hydrometer in it you can do a rudimentary test in your tank. Remove the hydrometer from it's housing and place it in the tank, at 70deg (21c) the hydrometer should read 1.15 SG. (Note - this method is only for the 12ASF method). The results will be somewhat skewed if there's dissolved aluminium in the tank if it's been used but it will give you a good idea of the concentration. Again, this a rudimentary method of testing and does not replace proper testing using Titration.

            As for agitation, an aquarium air pump is fine. Just run the line to the bottom of the tank near your parts but not directly underneath.

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            • #7
              I'll try to apply an aquarium air pump to my anodizing setup and report the result here.
              thanks for your advice sir.

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              • #8
                thanks for your advice, right now I am applying agitation system and had a good result. But i have another problem, I am anodizing 2 different part (1 part for 1 procces so I am running 2 procces anodizing) and the result have different color. After dyeing I am checking that part and have same color but after sealing the part have different color. Is sealing can cause bleed out ( Iam using cool sealant).
                Thanks for answering my problem.

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                • #9
                  Often if two parts are run separate there's a possibility they will have a slightly different colour based on many factors such as alloy of each part (if it's not the same), electrolyte tank temperature from run to run, Length of time each part spent in the dye tank and it's temperature to name a few.

                  As for your sealing method, the cool seal products are very hard to control hence why the hobbyist should not use it. I'd rather run the mid-temp nickel acetate sealant. Since it requires a slightly lower temp that traditional "hot seal" methods it helps to reduce dye leach but provides a decent seal.

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                  • #10
                    I am now perfectly anodizing aluminum with same color with each load (1 part each load/procces). After that I try to increase my load to 2 parts each load/procces but the result is 1 part anodized perfectly and 1 part not anodized at all (I ensure the connect point from wire to each part tight enough), why this incident can happened? For anodizing many part in one load, what are the factors affect the procces of anodizing?

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                    • #11
                      Either your power source isn't set up correctly and it's not getting the required amperage or one part has lost connection. No real way of knowing when you have so many variables that you can't confirm for us.

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                      • #12
                        I am using power supply 12 V 3 A and using alumnium wire to hold 2 part of aluminum in the end of wire (bend like V-shape). For the other parameter I am using like before (first post in this thread).

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                        • #13
                          So, that's all you got for power total? I think you need to either stick to one part at a time or get a power source capable of 14 volts and more amperage.

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