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ano outcome with no dye

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  • ano outcome with no dye

    Just curious........

    When I dont use dye, my parts come out with more of a greyish color as compared to parts I can buy that are "silver" ano'd. I compared to a couple different parts from different places, so I dont think that they are all bright dipping.

    I heavily polish, use caswells cleaner and desmut before ano. Any ideas on why my parts arent as silver?

  • #2
    Been there and done that, we cut the time back now for clear parts, otherwise they get tinted. We anodize ours at 9-10 amps current density on Ti racks for about 30-35 minutes, and they look good. Thats about .0003-.00035" thickness going by the 720 rule. As a comparison, we do the colored parts 50-70 minutes, depending on alloy, intended final color, and type of surface finish (as machined, tumbled, etc.).

    Your setup might be different, and so some trial and error testing may be required to get it dialed in. Also, I think lower current density like 5-6 amps will do a nice job too. If you are polishing them up good before hand, you should be able to get a very attractive clear anodize, better than bright dip in my opinion. Parts that are bright dipped are often anodized for shorter times or lower current density, even when colored, to preserve the gloss and clarity.


    • #3
      sounds like ti would work. What about parts that will be faded silver to some color?


      • #4
        That is something I haven't tried. If I were to do that. I would probably do some test parts, to see just how long the parts could go before the clear was no longer a nice "silver", and then try to optimize the dye conditions.

        I do think anodizing at lower current density may be an advantage, it seems to stay a more natural color when thicker coats are done.


        • #5
          M_D hit it right on the head.

          The lower the current density, the clearer the anodized layer.

          As examples; LCD produces layers that are almost perfectly transparent, Type III (Hardcoat) produces layers that are grey to bronze in color. Conventional Type II (10-18 ASF) produces yellowish layers.


          • #6
            Hey M_D,

            I saw some pictures of your parts. Man, those things are beautiful!! Question, which lathe and mill machines do you use to make those parts? Yours look to be very high quality. I have been trying to decide on some machines but just can't make up my mind.

            Sorry I hijacked this thread, but the PM feature is disabled on this board so I had no other way of contacting you.. Thanks!


            • #7
              I search through the post and found this posting that relates to some questions I have.

              I stripped and anodized some parts last night did a slow fade from color to silver anodized metal. We are extremely happy with the results however the silver anodized parts have a more matt, less shinny / glossy finish. We used the 720 rule for a max anodized layer.

              After reading this post I assume cutting the anodizing time will result in a thiner layer that is shinny / glossy. If I’m using the 720 rule and I anodize a part for 120 minutes at 6 amps my coating will be .001” thick. Going by what MD said I will have to achieve a thickness of .00035 for a shinner surface. Using the 720 rule (720*.35 = 252/6Amps = 42 minutes). So if I anodize my part for 42 minutes will I achieve a shinier coating? I’m not using Ti racking but I’m using a CDW unit to attach my aluminum wire to my part, does this affect my numbers?

              Finally not knowing how the thickness of an anodized layer affects the coating on the part I assume that the coating is less durable going from .001 to .00035. Is this a trade off you have to live with, finished look vs. durability?

              Thanks again for your help.


              • #8
                In theory, yes.

                What is considered the "standard" coating thicknesses in anodizing is generally derived from the milspec for anodizing, MIL-A-8625F. I think youi can download it from among other places.

                A Type II layer 1 mil thick is regarded as "too thick" for most purposes. Don't be mislead in thinking that the 720 Rule is recommending this thickness. For dyeing purposes, anything over 0.7 mils has no advantage, the dye (any dye) will not penetrate any deeper than this.
                Thinner coatings will retain a metallic appearance, and more gloss. This is at the expense of deep color, they will appear more pastel. Thicker coatings will appear more matte, can be much darker, and loose the metallic appearance. Which is "better" depends on what effect you want to produce.
                There are limits; too thin won't retain the dye, too thick can cause coating cracking problems, anodize is a ceramic.

                Using a CDW will greatly aid in producing coatings that are very uniform and repeatable, because the electrical connection at the work is as good as it can get with this method. Recall that the anodizing reaction itself places this connection under severe electrochemical attack. M_D correctly always mentions Ti racking when he is discussing numbers, because this is a qualifier. He is using Ti racking not because it is "better" but because it provides the throughput he requires for business purposes. As always, this is a tradeoff, Ti racking make a lot of sense in M_D's case.


                • #9
                  Fibergeek: Thanks again, all of your post have been a big help. My Son and I have just finished a test fade on a inexpensive marker and we are very happy with the results. You could say it is a culmination of all of the replies I received from you and M_D. Thanks again!


                  • #10
                    Speaking for M_D and myself, you're welcome.

                    I would say however, that you have the most to do with how rapidly you came up to speed in anodizing and dyeing. You can read and interpret written directions accurately, you know how to run and control experiments effectively, and you have an eye for detail. These admirable traits practically guarantee success in most any technical endeavor.

                    I would encourage you to try your hand at troubleshooting some of the problems you see posted here. I'm sure you read them all, and I'll bet you know the correct answers to many of them. Troubleshooting will sharpen your skills. If you find that you need help in solving someone else's problem it will be provided, in in an advisory manner.

                    Besides, you write very well.


                    • #11
                      Thanks very much for your wonderful comments Fibergeek. I’m sorry it has taken so long to get back to you but I have been busy with the seasonal stuff trying to get things done before Saturday.

                      Your suggestion as to trying my hand at troubleshooting someone else’s problems was a pleasant surprise. I feel I’m not quiet ready to advise others yet but I also feel I must give back some type of service to the forum as the forum has helped me immensely. I have received a lot of help using the search function and finding a thread that relates to my questions. There is a question now on the forum asking the number of times a paint ball marker can be re-anodized. This question has been answered thoroughly by you and M_D in a previous post. Simply replying where the post is with a shortcut to that post can save a lot of time and hopefully teach people to use the search function in this forum.

                      I would be happy to try my hand at answering questions if I know the answers but would like to direct questions to answers already posted in this forum. Thanks to you and M_D the Caswell forum has to be one of the best sources of information available on the internet concerning aluminum anodization. Let me know what you think.


                      • #12
                        You're right, we do spend too much time answering questions that have been answered multiple times before. Your idea is a good one.