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All set up and nothing happening

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  • All set up and nothing happening

    I know this is a caswell site but its the only active anodising forum I've found - so please be kind and give me a helping hand. I've been doing tones of reading over the past few months and think I have a pretty good handle on things. I've set up a small anodising station in my workshop only to be hit with tones of dissapointment.

    My process is as follows:

    Tank 1 - 5% nitric acid - set at approx 60deg temp for 10 mins
    Tank 2 - 20% sodium hydroxide approx 60deg temp for 10 min (tested up to 30 mins)
    Tank 3 - 30% Sulphuric Acid - approx 60deg for various lengths of time using a car battery charger at either 4A or 6A - the test parts are small so I'm assuming that the if there was too much amps that they woudl pit and burn. for the results....

    First cleaned and scrubbed
    Tank 1 - looks fine - not much happening - water sheets off after
    Tank 2 - bubble bubble and more bubble - seems to soften the finishing and make it a bit matt looking
    Tank 3 - bubble bubble bubble - gives a matt/grey finish to it. I've tried leaving it in for various amounts of time.
    Dye - this is the kicker - no matter what I do, using clothing dye of types people have said works, the dye just sheets off the part.

    The only thing I've noticed is that there is a pink tint around the cathode during anodising - contaminate?

    PLEASE help - I was thinking of mixing up more eletrolite but I didn't want to waste what I had. Then there's the battery charger - is it just not up to it? The part seems to be conducting due to the current.

    As for material I've tried different 6063's and 60601's of scrap I had here and nothing - again please be kind and give me a hand! -> yes very sad

  • #2
    Where to start...where to start?

    First, Caswell only supports the Low Current Density process of anodizing, so all my responses will be based on this process. Based on your post, I'm not exactly sure where you got the information you used, although I suspect it was from the 'net'..

    I'm not familiar with the use of nitric or sodium hydroxide use/concentrations since I use the Caswell products and just follow their instructions.

    First, your anodizing temps are too low, if they are in F. If they are in C, then they are too high.

    For LCD, the ideal temperature range is 70-75F, with 72F probably being ideal.

    Clothing dye is for clothes, not anodizing. Sometimes it will work, but usually it does not. It also fades quickly in sunlight since it is organic.
    A quality dye, specifically for anodizing will go a long way to getting a good color penetration.

    Your electrolyte is too concentrated. LCD uses about a 5% concentration (by volume, not weight). When the electrolyte is too concentrated, it eats away the anodized surface faster than it is created, resulting in no coating.

    Using a battery charger is just asking for trouble, IMO. Its difficult to control the amperage and usually doesn't have sufficient voltage. Fibergeek has some posts here about using a VCCS to give some control over the charger, but I haven't bothered. You can buy a supply cheap enough that its not worth the time, effort or potential issues involved.

    There is effectively no difference between 6061 and 6063 as far as anodizing is concerned.


    • #3

      I've been trying to get my info from a number of places but yet mostly on the Net - a but unfortunately it seems - I do have some books coming in the next couple of days so that should help.

      I don't care what method it is as long as it works

      My goal is to get the anodising working in a very small setup before investing any more money in it - hence the clothing dye. I don't care if it fades, etc - as long as it works a little.

      Okay - so I'll pick up a cheap water heater and get the temp to about 72F.

      With the electrolyte I'll try it at a lower concentration - The bubbles are really coming off of it - its like an airstone - would that indicate it is indeed disolving the surface faster then its being created?

      If you guys help me sort this out I'll send each of ya a wee token!


      • #4
        I'd suggest you sell the books on Ebay, or dump them. My experience of all this information, (and I've been doing the tech support for years) is that they simply confuse the issue.
        If you want a bunch of people to actually help you with this, then you have to stick to some basic rules.

        First, let's all drive on the same side of the road.
        Now, let's all actually learn to stop at STOP signs.

        Get the idea? We can all work together and follow a path to actually get to where we want to go, as long as we all drive the same way.

        If you want to drive against the flow of our forum, then you'll crash.

        Get with the program -we use - and dump the other stuff.

        There are thousands of other guys on this forum doing that. If you want to speak their language, use the LCD system.

        Mike Caswell
        Mike Caswell
        Caswell Inc
        Need Support? Visit our online support section at


        • #5
          Originally posted by kickn
          .............My goal is to get the anodising working in a very small setup before investing any more money in it - hence the clothing dye. I don't care if it fades, etc - as long as it works a little.

          With the electrolyte I'll try it at a lower concentration - The bubbles are really coming off of it - its like an airstone - would that indicate it is indeed disolving the surface faster then its being created?
          The anodizing dye does work best. If your anodizing is right, other dyes like clothes dye and food coloring should work to some degree for testing if the part is in the ballpark concerning dying characteristics.

          Bubbles will come off the part when it is being anodized, although it wouldn't indicate whether it is anodizing well, or not. If the current is lower there will be fewer bubbles produced in a given time frame versus a high current which will create more vigorous bubbling. I don't think I would use the bubble meter to adjust the current though............. and it doesn't indicate that dissolution is taking place.

          Small parts do not take much current, so you need to be able to regulate the current to a finer resolution than larger parts. Just because they aren't burning doesn't mean you don't have too much current.


          • #6
            Well said M_D, and (as you know) you are entirely correct.


            • #7
              Mike is dead right too. You have to learn to walk before you can learn to run.

              Be advised; Caswell will not support anything other than LCD. LCD is his product, and it works as advertised. What you get from the rest of us is not restricted to this, but is entirely correct. Caswell recognizes that the needs of commercial applications are not the same as those of the hobbyist. He will allow commercial variants to be discussed, but bears no responsiblity for them, they aren't his product. This is both fair and correct.

              The books are useful, (most of them anyway) but you have to know enough to interpret them correctly. read them, and then ask "why?".


              • #8
                I appreciate the feedback and even though I live in the UK I will try to drive on the same side of the road

                I won't be selling the books on ebay (mostly because they are from the university library) and secondly because I do want to increase my understanding of the anodising process.

                I'm fine working to the LCD method and would still appreciate your help. Unfortunately I cannot order chemicals and such from the US because of shipping restrictions. I am hoping to get this method working here with some slight substitutions.

                So in terms of 'rules to live by' - what are they and what is the flexiblity in them? I would like to be clear in saying that this isn't a challenge against them but a please for further understanding of them.

                To continue with my anodising problems would it be safe to assume that if the parts are bulbbling (almost like the same as an airstone with a small air pump) then the voltage and/or current is there?

                If the power supply is okay then it has to be to do with something else. The etching step seems to be working okay in that it does look like its desolving the very edge of the material (leave it in long enough) so that seems to be okay.

                Would it then be the electrolite? the pink tinting is an indication is it not of some contamination....iron? Possibly in the water? The second is that it may be too strong - is the LCD method based on a 10% v/w? My source here is 98% sulfuric acid.

                And again - thanks again everyone for your help. I know I'm working outside the box a bit but I would love to get this working


                • #9
                  Just be patient, the membership will get everything straightened out for you. If we threw all of the information at you all at once, you will get confused and this will take longer. We know this from experience, we were all beginners once too.


                  • #10
                    I understand how some chemicals would present shipping issues. Unless I am mistaken, some things like the anodizing dyes and sealers should be able to ship without problems.

                    I saw where you are getting a power supply with Fibergeek’s help, and that he directed you to an acid concentration chart for various types of anodizing. So, you are off to a good re-start. You have to control all critical process factors within certain tolerances, and then you will be successful.

                    So far, from what I have read, it looks like you have learned that properly controlling the current, having the right acid concentration for the current density you will be using, and operating within a certain temperature range are 3 of the keys to success.

                    One key I am not sure if you understand or not that is a part of this group (actual anodizing, versus part preperation and the post anodizing dye/seal process), is properly calculating the required current for a given part size, and the anodizing time for the current density. The other is you have to have good connections, especially the one on the work piece that will be submerged in the electrolyte acid solution, otherwise the whole electrical end of this will be full of ups and downs.


                    • #11
                      With all your great help (and I meant it when I said I would send you a thank you on my first success! it won't be much but I have a few neet things around here I used to sell - just PM me) - anyways I'm sure I'll get there.

                      I'm not so worried about the connection as I can actually screw it to the part. I have places that aren't finished surfaces. I'm assuming that if I used a titanium screw that I could re-use these?

                      On the finishing side - my initial thoughts where to beadblast the part - but thats a bit time consuming. I had someone mention a while ago that it could be etched to achieve a similar 'matt rough' finish. Has anyone had any success with that process?

                      Thanks again


                      • #12
                        Doesn't Caswell have a UK distributer? I thought he did.


                        • #13
                          Is it wirralfospray?

                          If it is i've already contacted them about dye's and stuff - the other kit I already have.

                          If its not then please let me know who it is and I'll ask them about some of the other chemcials/etc.


                          • #14
                            Speed Demon Motorcycles
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                            Latchford Lane
                            Hampshire, GU35 9JD

                            Phone: +44 (0) 1420 474961
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                            Mike Caswell
                            Caswell Inc
                            Need Support? Visit our online support section at


                            • #15

                              I'll address the question you had early on that hasn't been answered.

                              The pink residue.
                              Aluminum sulfates, a byproduct of the anodization reaction on aluminum, normally deposit on the cathode. The color should be white or grey. This isn't generally a problem unless you let it build up, and it deceases the conductivity too much. Its easily wiped off of the cathodes if you get it before it hardens, The pink deposits indicate contamination. The electrolyte and the dye should be made with distilled water. Chlorinated water is trouble, the chlorine iron interferes with proper pore formation. You may be able to get away with tap water in the other operations, it depends on your water.