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  • Where do I start?

    First I would like to give Kudos to Caswell. They really stand behind their products! As a newbie to anodizing I don't understand everything I know. We operate a gun refinishing shop and have recently added an anodizing line with Caswells equipment. We might be slow but we are not stupid, we follow instructions. Our first ever attempt at anodizing was on an AR-15 receiver with a bead blasted matte black finish. Wow! It turned out great. Our second attempt has proven frustrating. The first batch was with a few small AR parts and a Winchester receiver. All parts were bead-blasted before immersion in the degreaser. The parts were in the anodizing tank for about 1 and 1/2 hours when the reaction off the GP plates stopped. we are using the 20amp LCD power supply. The voltage output on the supply went to zero when the gassing stopped. What gives? Is this normal? Next stop was the dye tank for the appropriate time. Then to sealant. Coming out of sealant 3 out of 4 AR parts did fairly well. The dye rolled right off the Winchester receiver. OK, we said, try again. The Winchester was once again bead blasted and the process repeated. Into the anodizing tank we go. The readings on the power supply start out at 4.5 amps and around 12 volts. As the process progresses the voltage slowly drops. This time it went down to 6.9 and then started to climb. This time the solution took on a grayish look as did the receiver. After about 2-1/2 hours we removed the receiver and went on with dye and sealant. The dye did not come off but the peice is not perfect either. For those of you still with this adventure a few questions besides the obvious what are we doing wrong. Is there a test to ensure that the metal is in fact aluminum? There are some alloys out there in guns. Could an alloy cause this problem? the gray color in the ano tank. Is this normal? Should we replace the acid solution? We did clean the GP plates before starting. We used the Titanium wire for the Winchester and it did get quite warm. On the first run with the AR we used aluminum wire of a much greater thickness. Any feedback will be greatly appreciated!

  • #2
    Re: Where do I start?

    Where to start is right. First off material. Unless the part is made of billet, it is hard to tell what metal it is or if it is a mixture of several. I usually can tell if a part is going to anodize after the etch and deox steps. The part turning gray is from being an alloy or impurities in the cast. I've run into zinc diecast and magnesium mixes, aluminum mixed with other metals for strength and high copper, silicone contents for a better pour and casting. The gray in the electrolyte has always disapated after a few hours in mine. The electrolyte should be alright.

    If you do much cast, you'll see your share of smut problems and parts that won't hardly anodize. On cast parts, it's recommended to use an etch and a deox/desmut step to help cut down or eliminate smut problems with impurities such as copper and silicone.

    If your hookup to the part is getting warm, the gage is to small. Go to a larger gage or multiple hookups.

    Questions to get a better picture.
    You said you ran a 4.5A setting on the PS. What was the SA of the part?
    What is your tank temp.?
    How is your tank agitation?
    Is the PS a 20A 30V CC/CV?
    What was your peak voltage?
    You said the dye rolled right off the Winchester receiver after coming out of the sealer. Did you rinse the part with RO or distilled water between the steps?
    SS
    Last edited by sswee; 02-24-2006, 11:13 PM.

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    • #3
      Re: Where do I start?

      SS,
      Thanks for responding. It is very possible the winchester part is an alloy. You say that you can tell after the etch and deox steps. What do you look for? Our anodizing tank was at ambient temperature (60-63 degrees). The agitation was good with air bubbles from the pump supplied by Caswell. The PS is a Caswell supplied 20A, 30V CC/CV. Now for the less specific info. We have a lot to learn about calculating SA! For the sake of argument and to make your response easier let's say "I'm not sure". The part is a rifle receiver approximately 7" long by 2" wide by 2-1/2" tall in a U shape. We set the amps at 4.5 and let the voltage regulate itself (?). The voltage started around 12.5 climbed a little then slowly dropped to 6.9 with the amperage remaining constant at 4.5. OK then, after you say hey stupid, what next?

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      • #4
        Re: Where do I start?

        I may go over somethings you already know so don't take offense.
        I prefer to run at 60 to 64 degrees. It should give a smaller pore size and a more durable finish.
        Agitation is very important. Parts develop a heat pocket around them if you don't have enough agitation.
        On your PS, you should turn the voltage all the way up and the current down. Then just dial up the current to the desired setting. The PS may not flow current until it's over what you want, normal, just dial back down to where you want if it happens. The voltage should start low and climb fast for the first 10 to 20 min. then slow climb for awhile and gradually descend or slow climb to the end of the run. This will depend alot on the material grade.
        The numbers you gave for the part size would give approx. 98" of SA depending on wall thickness and contour. That size part at that amperage would give you a CD of 7A per square foot. The part should have run for 102 minutes for a 1 mil coating. All in all your run was in the margins for the calculations except the run time and the voltage. Possible some of the problem was the run time and dissolution. Possibly a little connection problem and maybe a material grade or a combination.
        The etch should have almost a foaming action with aluminum and usually a slight gray tint on the part. On the problem parts, they will smut heavier sometimes to almost a black film. The more they smut the more difficult they'll be if you can do them.
        The deox/desmut will dissolve the smut and turn the better parts almost a white color. Especially with bead blasted parts, I get a better, more even dye with the etch, deox steps. If the part grays in the deox, it won't anodize well if at all.
        SS

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        • #5
          Re: Where do I start?

          SS,
          Thank you very much for the reply. We will study the 720 rule more and attend to the points you mentioned.

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          • #6
            Re: Where do I start?

            Originally posted by adavislock
            SS,
            The part is a rifle receiver approximately 7" long by 2" wide by 2-1/2" tall in a U shape. We set the amps at 4.5 and let the voltage regulate itself (?). The voltage started around 12.5 climbed a little then slowly dropped to 6.9 with the amperage remaining constant at 4.5. OK then, after you say hey stupid, what next?
            If it's a one of a kind, or hard to replace, plan on scrapping the part just in case you do, or at least be able to paint it. Look for steel or other metal plates in the receiver, I have done a 10/22 receiver and it took me along time to find out the right touch for cast that I plan on posting one day. I would like to get some photos before posting

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            • #7
              Re: Where do I start?

              rclint,
              We tried to anodize this piece again with dismal results. We now believe that it is some form of alloy as it seems heavier than it should. The next step is powder coating. The problem of exotic alloys seems to be commonplace in gun manufacture. During this same period we had a Sierra revolver that we thought was aluminum, got no results anodizing, but got colorization of the metal with cold blue. Other than trial and error I wish there was a test for aluminum before we spend the hours required for an anodizing run.

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              • #8
                Re: Where do I start?

                The learning channel is great. I saw on a show about recycling something I had heard about but never seen. A rather large handheld unit that was a spectrograph. It made a burn mark on a piece of aluminum with a laser about the size of a pencil and told the grade of the aluminum block on a LCD screen. There is equipment out there to do what we want to do but the big question is at what cost. I would probably die at the cost of the high tech gadget I saw. There are some basic chemical reaction tests to give general ideas of what a metal is but not many if any I've found to be very reliable. Just because a reaction test indicates aluminum, it cannot indicate what else is in there with it. If anyone finds something even fairly reliable, there are many like myself that would appreciate the sharing of the knowledge.
                SS

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                • #9
                  Re: Where do I start?

                  On the cast parts I have done, when I tried etching the parts... that's the first mistake, part turns grey smut, and even some copper come thru in places.

                  My way of doing cast parts....

                  I do not even fool with the buffer now, cast will not give that candy color anyway if it's a problem piece like we are talking about ( I have done some cast parts that anodized like billet, wrought etc)

                  First get the little scotch brite wheels for your dremel tool, or a bigger one for your buffer (slow buffer), or sand by hand I have went to 1000 and even 2000 grit but worthless, 800 grit is a good stopping place, dremel tool takes about 15 minutes, hand sanding 1 hour.. compared to same part being done.

                  Now clean the part good after you do all this, my last test on cleaning was cascade dishwashing soap for dishwasher, I noticed a bleach smell so not 100% sure just how this will work yet, but it cleaned better than anything I have used so far

                  next before you anodize, soak in the casweel desmut for 10 minutes at room temp, stir the part around some, don't let it sit on one side, then give a water bath to get rid fo any acid.

                  Make 2 connections on cast, so your part will not heat up in one spot, or build the thicker layer all in one spot, I use a sput welder (subject receiver 10/22 specific, but any part this size)

                  next anodize at up to 8 amps sq foot, when finished remove water bath again, then directly into the dye, go full color on this, because you will get haze, and also sploches if you try to make a lighter color.

                  After dye, then do the boiling water seal. Very important here, the cast I think makes bigger pores than the wrought/billet( specific 10/22 receiver,I watche dthe volts go from 4 all the way to 31, then back down to 8 for a 1 mill coating, this si my reason for thinking of big pores), so steam it for 10 mintues, then a 1 minute dunk in the boiling water, this is the time of truth...

                  Your part may have some smut/haze, don't worry. This is the cast fix, the problem I have seen is the smut gets sealed in at the top of the pores, so you buff this part either by hand or on a 1100 rpm or close buffer with a small wheel ( I think i have a 4" I use) with the blue compound or rouge, you will see the color come in, be careful here because you can go right thru the anodize layer. It will haze, go clear then come back full color, leave the corners along...

                  Now the problem with cast is smut, and we seal it in when we dye, it's at the top, what we need is some way to clean this smut off before we dye, after we anodize, without harming the anodize, it's the same grey smut you get when you etch a cast piece, an dthis can be wipe off, but when anodized it's in the pores, so will bleach work (bleach is latest thought) maybe a nylon brush on a real slow buffer or by hand i don't know 100% yet but working at it.

                  Another thing, maybe watch the volts, when they peak, the start dropping the pore size should be at the best point here, I think ( I get in trouble a lot for thinking) maybe after the volts drop say 8 volts stop off here, then see what happens, I have not tried this yet either, just some thinking

                  Perfection ? we need a solution to dip cast parts in to remove any and all smut before dye that will not harm anodize layer ? Caswell may be able to come up with this ?

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                  • #10
                    Re: Where do I start?

                    Just to add don't try the cascade, leaves a film LOL

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                    • #11
                      Re: Where do I start?

                      We gave up on the Winchester receiver. It will be powder coated. We ran two smaller parts, a sight ramp and part to a charging handle for the AR15. Used the calculator on the web site and WOW!. Oh yeah, it's great when things work. Looking forward to the next project. Have you tried powder coating? It's so cool. We did the slide on a Browning in red (don't have the black yet) and WOW. Can't wait till the black comes in. thanks guys for all the help and support.

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                      • #12
                        Re: Where do I start?

                        rclint,
                        Have you come up with a good smut remover for cast yet? I am thinking a giving a little bench top ultrasonic tank a shot. I read somewhere (I think a different finishing forum) that a finisher was pulling cast from his deox tank dip rinsing twice then going straight to the ultrasonic tank for a quick desmut dip.

                        He claimed the pieces came out completely smut free.

                        Another thought is pulsed electrocleaning, but that seem to get complicated fast.

                        Dave

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