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First anodizing project, 3 color splash anodizing, picture and questions

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  • First anodizing project, 3 color splash anodizing, picture and questions

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ID:	141805 Hi guys,

    I've been involved in a lot of hobbies over the last 20 years that have had anodized aluminum parts and have always wanted to learn to anodize but never set the time aside to do so until yesterday. I did quite a bit of reading and took a lot of notes over the last week and tore down one of my paintball guns as a test item. I wanted to keep things easy and cheap for this attempt and just used rit dye and I didn't polish my parts beforehand because I wasn't sure if it would even work! I'm looking forward to using caswell dyes next time around. I have attached a picture of the finished product and I have a few questions I hope someone can answer.

    First off there is some color differential in my orange pieces which I'd assume is because I did them individually, Ideally would it be best to anodize them in the same tank at the same time? If so, when i put them in the dye bath will they take color equally or do i still need to check them and possibly pull smaller parts out sooner?

    Secondly, how long does the anodizing process last? I ran into a slight issue a FEW times on the largest piece with 3 colors where the final color, orange, would not take completely, it would be very faded. My process was...

    anodize for 1 hour and quick rinse
    black dye for 20 minutes
    rubber cement with 10 minute dry time(for the black splash)
    bleach to remove the areas of black not covered with cement, this took a couple of minutes swishing the part around in the bleach
    rubber cement with 10 minute dry time(for the silver splash)
    orange dye bath for 20 minutes to even 1 hour to try to get it darker the first couple of failures

    That is quite a few steps and I was wondering if during that time the part might, lose its ability to take color at some point leading me to ask how long the part can sit before it wont take dye any longer?

    Third, is there a better method for removing the anodizing than easy off oven cleaner and a wire brush? It appears most info on the web suggest that but I would prefer something I could just drop my parts in and walk away and maybe use just a scotch bright pad when the time is right.

    Thanks in advance,

    Blake
    Last edited by Blakesgst; 06-20-2016, 05:03 PM.

  • #2
    Originally posted by Blakesgst View Post
    First off there is some color differential in my orange pieces which I'd assume is because I did them individually, Ideally would it be best to anodize them in the same tank at the same time?
    If you want color consistency, then the best you can do is process each piece identically the same. Does this mean they have to be run together? No, not necessarily. Running them together gives you the best possible chance of processing them the same. But even then, there is no guarantee. If a piece is racked loosely, it might not process the same. In the end you need process consistency across the board. This includes not only consistent tank immersion times, but also well maintained bath chemistry, and consistent bath temperatures. If you can maintain a consistent process, you can maintain your quality regardless of when or who processes the parts.


    Originally posted by Blakesgst View Post
    Third, is there a better method for removing the anodizing than easy off oven cleaner and a wire brush?
    Be careful of using a wire brush. It has iron in it which can embed in the part and cause problems down the line. Not to mention the micro scratching that can dull the finish. Normally you will just immerse the parts in the NaOH bath (sodium hydroxide essentially draino or lye) at a temperature of about 130-140F. The elevate temperature will speed up the reaction, so if you can't heat it it will just take longer.Normally my customers are only in the bath for about 30-40 seconds with newly machined parts, maybe 1-2 minutes if they are stripping a Type II coatings and up to 3-4 minutes if they are stripping Type III coatings. I have never seen aluminum oxide stripped with anything but NaOH. Be aware though that NaOH will dissolve aluminum. If you leave it in there too long, you will change the dimensions of the part.

    As for your second question, the anodize will hold up fairly well as long as it's not wearing on anything. If it is, you need to apply a type III coating which is a bit more difficult with the LCD techniques. Color don't hold up as well. Dyes are basically graded on light-fastness using a scale from 1-10 with 10 being very light -fast (holds up well to UV light). Cheaper dyes and certain colors (shades of red, pink, etc) tend to not be very light-fast. After dying the parts, you have to seal them or the dye will come out. Sealing the part will hydrate the oxide layer causing it to swell. In that swelling process, the pores tightness up and eventually seal and trap the dye. I know there are things that can happen in the bath that will cause dye not to take, but you are using some techniques that I have absolutely no experience with, so I don't think I can address that.
    kevin

    Process control doesn't give you good quality, it gives you consistent quality.
    Good quality comes from consistently doing the right things.

    Process control systems for Anodizers
    If a post helps you out LIKE the post
    I'm not an Amateur Metal Finisher. I've just been around the industry for a dozen years or so helping and consulting when and where I can.

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    • #3
      Kevin covered it pretty well but there are a few things that are of question from your post. You mention only running the parts for an hour. This is fine if you are using 12 ASF with an electrolyte density of 180g/L but not if you are using the LCD bath density. This may account for the lack of dye uptake on your orange parts you mentioned. When stripping parts it's imperative to protect things like threaded holes, bearing journals and so on or you risk tolerance distortion. Lastly you need to know that different alloys react differently when anodized. Paint ball gun components are made from various alloys based on the performance of the parts. Barrels might be made form 7075 for it's strength while receivers might be made from 6061 for another reason. This can cause issues when dying parts if there are two different alloys used in the gun, especially with regard to colour matching. All in all it appears as though you did fairly well for your first attempt. If you are going to get serious you should purchase the right chemistry for the job, it will make things more consistent and easier to achieve repeat success.

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      • #4
        Thanks for the replies guys.

        Kevin, good call on the use of a wire brush to clean. I noticed after i was done that in the orange anodizing i can see tiny little spots in random areas, i think they might actually be rust so i'll be sure to not use one again.

        Gardin, I definitely noticed the different aluminum types throughout the gun. Also you mentioned protecting threaded holes. I did not do that and ran into a couple issues with some leaks but was able to get them sorted. In the future, how do you recommend protecting those holes, typically they are about 1/8th inch in size.

        I am still curious how long after you anodize in the acid bath do you have to get the part in the dye and have it take properly? How long is my working time with the part etc, anyone know? I ask this because if i want to experiment with some other types of masking and more colors, is there a point time wise where the bare aluminum areas on the part wont take color.

        Blake

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        • #5
          I use silicone plugs of various sizes to protect blind holes when stripping old ano. As for length of time to dye. It's best to do it immediately while the pores are still wet but theoretically you could do it anytime provided the parts have not been sealed. Dye uptake might not be even but it will still work. I have had success dying parts months later, I just do a quick dip in 10% Nitric Acid first.

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          • #6
            We've always used the rule "don't let the parts dry out". If you can't dye them now, part them in water. I'm not surprised that parts can be dyed a while later as gardinhackle points out. I would just be afraid of contaminants if you wait too long.
            Process control doesn't give you good quality, it gives you consistent quality.
            Good quality comes from consistently doing the right things.

            Process control systems for Anodizers
            If a post helps you out LIKE the post
            I'm not an Amateur Metal Finisher. I've just been around the industry for a dozen years or so helping and consulting when and where I can.

            Comment


            • #7
              Wonderful Art, Best I have Seen. May I ask what type/name of the rubber cement, 10 minute drying time thar You Use?
              Respectfully, Jim "P"

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              • #8
                I Can't Find the Right Words for this "Masterpiece", It has "Put Me In My Place. Anyhow, may I ask the brand/type of rubber cement with a10-minute drying timeYou Use Please?
                Jim

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                • #9
                  Here is the secret I think you're missing. You need to re-activate the pores after bleaching and removing mask. You can do this in the same bath your anodize tank is made up of. About 10-30 seconds does the trick. The bleach needs to be 100% removed from the parts before 're-activating' for safety issues.
                  Last edited by xNocturnalx; 09-26-2019, 08:20 AM.

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