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  • New small shop setup

    Okay - first of all thanks for all your help in the past - the products are starting to come out great and we're taking them to market ( if you interested).

    Before I ask my question though I have one thing thats been bothering me. In the etching stage (just sodium hydroxide) a brown residue is released and is somethimes collected in small crevisous Okay - first of all thanks for all your help in the past - the products are starting to come out great and we're taking them to market ( if you interested).

    Before I ask my question though I have one thing that’s been bothering me. In the etching stage (just sodium hydroxide) a brown residue is released and is sometimes collected in small crevices and has to be scrubbed out. Is there a simple sulfacant that can be added or do commercial products contain these? Or is it a case of not etching at a high enough/strong enough mix?

    Anyways – back to my original question. I’m looking for any and all recommendations on setting up a small anodising station (although bigger then the one I have) to in a more structured environment.

    At ASF 4.5 a full set of parts (for one unit) takes between 21 and 23 amps so it generates a fair bit of heat. I understand what process is needed and have a 40A supply (so could do batches of 2 if I needed too) but my questions are more in terms of equipment.

    I am looking to do this as economically as possible and can see certain things being fairly easy (some of which I already have). Anyways here are some more specific questions:

    - what material are your tanks made from? I have been using plastic but didn’t know if SS was better for some of them?

    - cooling the electrolyte is going to be an issue. Yes TI heat exchangers are there – is this the best method? I was thinking of something more straight forward that would act as a heater and cooler – say a TI block with a pelt on one side and a heating coil on the other? Any ideas? I was also thinking that a temp control unit could be used to regulate the different devices.

    - for they dying baths do you switch solutions or have different tanks?

    - for racking – we have the sput welder and that works great – should the station be designed with a mobile rack system that moves with the parts from tank to tank?

    I think that’s it for now – this may become a longish thread but I would really appreciate the feedback so I can get a professional setup without spending money in areas I don’t need to. That said there is money to spend on what needs to be bought to make it right. I have been using simple chemicals for instance but will be moving to commercial mix’s as soon as its set up.



  • #2
    Sorry - two more thoughts here.

    I have been thinking about what machinery to use given that I've currently been using the steam sealing method. Should I switch sealing methods or use something like a commercial kitchen steamer? (or i could make one out of SS if needed)?

    Also -with the degreasing - would a commercial kitchen dishwasher not work great at cleaning the oils if come fairly harsh chemicals where used? It would be hot as well as aggressive.


    • #3
      I can only try to answer on a couple as you sound like you are fixing to go big time. Product looks nice.

      On sodium hydroxide - I use it for cast alum. and stripping anodize. It always leaves a residue that reminds me of soot. I just rinse it off with water and a plastic brush or toothbrush. The DeOx/DeSmut from Caswell does not leave a residue. What are the cases made of? It appears to be extruded or is it cast? I think it would be worth the effort to try the DeOx/DeSmut without the sodium hydroxide etch, and anodize 1 part to see if the etch is necessary on that material. On new parts, I just use the DeOx/DeSmut with no problems.

      On cooling - Fibergeeks setup is the best I've studied on. A magnetic drive pump for caustics to provide agitation and move to coolant through an saltwater aquarium chiller with TI heat exchanger. The pumps go for 90.00 to 150.00 and the chillers for 360.00 to 600.00 depending on size.

      On dyes - I have 15 colors now and each has its own tank. I have used the same tank for heating and then switch to another color. It is a real pain to do it that way because of the cleanup, so you don't contaminate you colors with each other.

      I can't say on the racking.

      Sealing - I boil to seal with and without nickel acetate. I've never had any problems since I switched to the Caswelll dyes. I really haven't sealed with steam only.

      After cleaning with many different things trying to pass water break test, I had thought several times of trying out the ole ladies dishwasher to see if it would work. I haven't gotten brazen enough to try yet. So I dunno.

      Let us know what works out and how. I'm borderline on getting bigger, running a 15 gal now.


      • #4
        I'm glad you like the product!

        Thanks for confirming the sodium hydroxide vs. DeOx/DeSmut formulas - i'm assuming the these commercial products do a better job of absorming the residue. Does the etching performance change significantly? Also - what concentration of lye do you use?

        The aquatic cooler does seem to be the cheapest option - its the TI core that is critical. Do you see any problems with this dissipating 800W of heat?

        On a related note i noticed that when I'm controlling a tight tmp to the 72deg that the parts come out slighly darker then I would preferr. I've done a few at about 60 (or less) and its much brighter but the voltage required is much higher - is the leaning more towards the hard andosing or is it something else i'm doing?

        On the dye tanks - my biggest problem is heating them - what do you u use to heat the tanks and do you put the parts in racked or loose? I was thinking i might get away with loose parts if i line the tanks with a stainless mesh or something so that there is very little contact points.

        How do you heat your tanks for boiling? I have been using steaming as its easier for me (using a wallpaper stripper and tile-lined box) to bring that up to temp then a very large tank of water. On colored parts I have been using a cold seal first and then steaming but I can't do this with natural as it leaves a green tinge.

        How about ventalation as well - I was thinking a simple fume hood would be good enough for the etching and anodising. Any thoughts?

        My plan is to sketch this up after I have all the info - if I posted that would you be willing to give me your feedback?



        Anyone else have any ideas on the dishwasher idea? or is this a pointless road to go down?


        • #5
          The DeOx/DeSmut does not leave a residue, just rinse and anodize. The only benifits to lye are stripping old anodize or when working with lower grades of aluminum that have alot of impurities in the mix. The last batch I mixed at 6% lye. It has been working good on poor grade cast and stripping old ano.

          What size tank do you plan? The more liquid the better, within reason. Fibergeek can say approx. what size chiller will be needed for the size tank with 800W of heat.

          The voltage variance is normal. The cooler the electrolyte temp., the more resistance. I prefer 60 - 65 degrees. The cooler temp slows dissolution to get a smaller pore size. This is probably what is causing your color difference. The smaller pore size should give the coating a better durability.

          Dye tank heating for me at this time is hot plate and large stainless stew pots. My plan is to change over to Caswell thermostat and ceramic heaters. They have 300W and 1000W depending on size of tank.

          Heat to boil is over propane. Ceramic heaters also planned.

          All parts have been suspended from copper tubing, either with sput connect wire or heavier gage wire and a seperate sput wire for electrical hookup depending on size and configuration. A racking of sorts in that I can lift the tubing, rinse the parts and go to the next tank.

          Fumes are negligable. A simple fume hood should be more than enough. It wouldn't have to be a very large CFM.

          I am always looking for ways to improve or at least make things easier. Feedback is free. Maybe I'll see something to make my setup better.


          • #6
            For 800W of power dissapation in the tank you will need at least 1 HP of cooling capacity, more is better.

            I like 70 deq. F, but use 6ASF or a little more (the M_D camp?) Not to say that Sswee is wrong, different balance.

            NEVER boil the dye, bad things can happen.

            Not well known; aeration (air bubbles) though simpler than agitation (electrolyte circulation) promotes (via acid mist) a real risk of sneak current paths (anode to cathode) usually through the racking method. the next best defense (the best is no acid mist) is vertical height of the power distribution. Watch out, this can really mess things up. Agitation almost never causes this problem (no or very little acid mist).


            • #7
              I run 6ASF on my parts. The reason for me running a little cooler is with my setup I've had better ability to flat line or arc up my voltage readings until the part is finished instead of a slow arc down. Possibly due to using aeration until I can afford agitation.


              • #8
                The brown residue left from etching or stripping is smut. You can remove it with the desmut/de-oxidizer from Caswell’s.

                In my opinion, sodium hydroxide (lye) etch removes oxide much better (at least faster) than the desmut/de-oxidizer, so we etch in sodium hydroxide, double rinse, and then remove the smut in the desmut/de-oxidizer tank (heated to a warm temp). It only takes from a few seconds to a minute to remove the smut and unlike brushing the smut off it cleans the entire part including hard to access holes and recesses. Heating the desmut/de-oxidizer to 100-120º F makes it work better than room temperature.

                Aside from the effect etching (or desmut/de-oxidizer) has on the gloss, you may or may not need to use it, depending on how much oxide the part has. If there is enough oxide present, and it is not removed, the parts will not dye as deep and will likely be somewhat blotchy. If you need to de-oxidize with out etching (dulling) the surface, there are various “non-etching” commercial products for that.

                On the dye tanks, I think for ease of use you want separate tanks for each color if they are to be used regularly. But you will need to work it out according to your needs.

                As long as the plastic tank is sturdy enough (don’t want an acid tank to break open) it is good, perhaps best. Nylon is the one common plastic I know of that is not friendly for use in the anodizing tank.

                There are all kinds of heater choices, from the ones Caswell carries to various others. For dyes the Caswell submersible ones work ok for us, they are cheap and one 300W will heat 30-40 gallons to 140º F, but it will take some time to do so, and you need to watch that the temp doesn’t get too high. You may want something with thermostats. Insulating all heated tanks pays big dividends in reducing the heater power required. Like fibergeek said, be careful not to boil the dye, in fact be careful to not dip parts if it is over 150º or so because it will partially seal the parts and affect the color.

                If you were doing enough parts on a regular basis, some type of bus bars for attaching the sput-welder wires would be what I would try. It makes moving the batch of parts from station to station much easier. When you dye the parts while they are resting in a basket or the tank, you will have a certain amount of blemishes where contact is made. Even when using a Ti rack, you want to keep the parts from resting again the tank surface (or eachother) through the entire dye process, although occasional contact shouldn't spoil the finish.

                I don’t know positively if the dishwasher would clean well enough or not, but I doubt it would. The cycle time is long compared to using a heated cleaner tank (between 30 seconds and 2-3 minutes), and it might be hard to consistently unload the parts without touching them against something that might contaminate them. Plus, it may leave contaminants in deep holes and recesses, which will bleed out latter and spoil parts if not solution life.

                I prefer 70-72º @ 10-12 amps CD for the work we do. To be honest though, I don't see a visual difference all the way up to the high 70's. May be because of the agitation. We use the higher amps to reduce cycle times.


                • #9

                  Are you saying that agitation by itself is sufficient, without any aeration at all? That sounds better to me than using air lines and compressors.

                  On the subject of chemicals, does anyone know what is in the Caswell deox/desmut solution? If I could, I would buy it from Caswells, but I can't easily do so (being outside the US), so I need an alternative. I would rather go for the best possible desmut, than rely on just a sodium hydroxide etch.

                  I found one recipe for deox/desmut that is 26% Nitric acid, 22% Sulphuric acid, water to 100%. Does that resonate with anyone?

                  On the subject of tank material, I have managed to find out that the best plastic for ano tanks is either PVC, polypropylene, or HDPE (high density polyethylene). You can use LDPE (low density polyethylene), but it won't take as much heat. For info on plastic chemical resistance, check out




                  • #10
                    I am currently using Nitric Acid at about 10% for a desmut bath - the addition of the sulphuric acid is interesting and easy enough for me to test - i can let you know if you want.




                    • #11
                      You can't have agitation (as we mean it) wihout aeration. Agitation is more efficient, and more complicated.


                      • #12
                        Originally posted by kickn
                        I am currently using Nitric Acid at about 10% for a desmut bath - the addition of the sulphuric acid is interesting and easy enough for me to test - i can let you know if you want.


                        I can say now that equal parts nitric acid and sulphuric acid (botha bout 10% right now) works pretty good - you can see the smut fade away in seconds.




                        • #13
                          Thanks for that. I'll stick with air then. A guy I know who used to do anodising in a big shop told me that they used to aerate at large volumes - he said they pumped as much air through as they could without slopping the acid over the edge of the tank. Mind you he was probably using a higher ASF.

                          Also thanks for the info on desmut. I'll try the formulation I have (which is a Henkel one apparently), and let you all know.

                          Does anyone have any info on successfully desmutting high-silicon alloys? I gather you need to add sodium flouride, but then you get hydroflouric acid, which is nasty stuff. My local chemical supplier said it was the one acid that he was afraid of!




                          • #14
                            possibly a silly question here - and I think i understand why i'm getting the results i am - but i'll ask it anyways.

                            Has anyone had any success with mixed sized batches? Ideally i would like to do a complete unit (partly because i have problems regulating the temp right now) at once but this involves both big and smaller parts.

                            The result is that sometimes the smaller parts are much darker. Everything is cleaned, racked, connected, etc the same so I don't think its the connections.

                            Any thoughts?


                            • #15
                              Several possibilities and maybe a combination. If the parts have the same finish and are the same material grade, with good connections, then the most likely is temp related. The smaller parts are getting warmer allowing more dissolution resulting in a larger pore size. The same amount of current run through a smaller part will generate more heat. I have been suspending my parts as low in the tank as possible under the principle that heat rises, trying to get the pore temp down because of a borderline dissolution problem. It has seemed to work so far. What's you thinking on your problem? Maybe Fibergeek or M_D will confirm something or let us know the right direction.