I figured it was about time to set up my anodizing line so that it would be more useable. I had played with anodizing awhile back and really struggled. I was able to succeed at it however it was a result of more luck then chemistry. Anyway…I decided it was time to revisit the project and hammer some knowledge into my head. I am pleased to say that with the anodizing process I have gained a solid understanding of the chemistry, and factors involved, and therefore have been able to reproduce consistent results using proper set up and calculations.

The type of anodizing I have been doing is considered LCD (low current density) CC (constant current) Type II anodizing. I want to be able to anodize some of my machining projects and since the size of my lathe determines the size of project I don’t need a huge tank to perform the process. Right know I have set myself up a 4 gallon bucket which is plenty of room to perform the current (pun intended) tasks.

For those of you who are new to home anodizing the process is probably unknown. For myself I separate the process into 2 sections. First one is the process of anodizing, the second is the process of dyeing which is what gives the aluminum its color. For now I have directed my attention to the anodizing portion.

I have been practicing my aluminum TIG welding on scrap metal and decided it was time to put my practice to use. Using some 6061 aluminum flat bar and round bar I welded up a hoop to sit on top of my 4 gallon bucket. The hoop allows me suspend my parts into the anodizing solution as well as holds my agitation lines. I welded up a bracket in order to clip a 150 watt aquarium heater onto the side of the tank. Then I built some 6061 aluminum cathodes to aid with the “negative” side of things.

I was able to track down a used power supply which was in great shape. The unit I am using is an Astron VS-50M which is a 50 amp 15 volt variable DC power supply. It has plenty of jam to perform the smaller projects I am anodizing.

Sample dye colors on aluminum knobs

With the tank set up coupled with the massive amounts of research I had done I started turning out great consistent, well controlled results. Since I run small parts through the system I rely on a DVOM to monitor my current draw which allows me to dial in the power supply.

Once the part is anodized it can then be dyed to any color. I have 6 dyes, some of which I have sampled and some that still are waiting discovery. The process of dyeing is nothing more then soaking the part in the dye tank, at the right temperature, for anywhere between 1 to 15 minutes depending on the shade of color desired. Once dyed the aluminum can then be sealed. I have experienced some blotches with some colors which I believe is a result of poor cleaning of the part. The cleaning process is incredibly important to the success of the entire operation. I have a cleaning sequence I perform however it needs some tweaking.

Overall I am pleased with my results. The setup is compact and performs its function. Overtime I hope to build up a sample library of anodized finished, colors, and dye techniques to be able to reference to.

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Comments
  1. Chris Muncy says:

    This is one of the things, as well as powder coating, that I want to start this winter.

    Nice looking results Gord.

    • gordsgarage says:

      Thanks Chris. I like the idea of setting up for powder coating but there is no way I can fit an oven in my current garage. If you haven’t already you should check out the Caswell finishing forum located here. There is lots of info on DIY powder coating and oven building.

      Gord

  2. Jason Garber says:

    Hey Gord,

    This is awesome. I never considered it could be done on a small scale. Would you have any interest in trying it out on a small 3×1.5×1″ piece of aluminum for a rubber band gun receiver?

    Take care,
    Jason Garber

    • gordsgarage says:

      Hey Jason. The anodizing works great on the small stuff once I finally figured it all out. I will be able to increase my tank size should the need occur. Right now my power supply limits me to apporximately 8 square feet at a time.

      Rubber band gun reciever? Hmmmmm…..interesting. What do you have in mind? Have any pictures?

      Gord

  3. Jason Garber says:

    Hey Gord, my kids and I have been building a series of nicer and nicer rubber band guns. We recently completed a short production run of assemblies (2-shot). They are machined out of rectangular aluminum tube, with steel dowel pins and W-1 tool-steel parts. The Trigger is also aluminum.

    http://blog.gahooa.com/2010/10/28/rubber-band-gun-m6-001/
    http://blog.gahooa.com/2010/11/08/detailed-assembly-of-rubber-band-gun-m6-002-to-m6-005/

    We’re taking a lot of time to make nice mechanisms and stocks. I was thinking it would be really cool to have a black or colored receiver and trigger instead of plain 6061 aluminum.

    Of course, only if you were interested in refining your technique 🙂 Feel free to email me to discuss further if you are interested.

    Thanks!

  4. paddy says:

    your parts look professional gord would love to see how u dye them.could you tell us more about the process of anodizing i find it interesting.great blog keep up the good work gord look forward to the next one.

    • gordsgarage says:

      Thanks for the kind words. I am going to be making more anodizing runs soon so perhaps I will try and take some more pictures and post a play by play of how I do it. Stay tuned!

      Gord

  5. Erik says:

    Can you recommend a good place to start looking for specs on how to anodize/dye or do you have any tips on were to start? Settings, voltages, amps, solutions, etc.

    • gordsgarage says:

      Hi Erik, there are a lot of factors invloved in getting set up to anodize. I struggled in the beginning because I had collected wrong information. A good place to hang out is on the Caswell forum found here. The forum has got lots of good information. The key factors that helped me in my success were figuiring out my water to acid ratio, which is 3:1 (3 parts distilled water to 1 part battery acid) and then fully understanding the 720 rule which helps you determine the amount of current and time requirements. Once I got my head wrapped around constant current and ASF (amps per square foot) everything else fell into place. I could write a step by step however it would be failry time consuming.

      If you have specific questions I can try and answer them for you. I find it very difficult to reply to general questions since there is a lot of information to respond with. Others have requested similiar information. I will try and make an effort to post a step by step of how I anodize in the near future. I just ordered more supplies on Wednesday therefore when they arrive I may be able to do a picture post of the process.

      Thanks, Gord

  6. Keven Coates says:

    Powder coating does not require any more room than annodizing. I just have a toaster oven, and it works great for the small parts. The larger parts i use the heater/reflector from an outdoor electric grill on an I.V. stand (medical) with a flexible gooseneck to position it. Cook one section to 400 degrees (or whatever the powder says) for 15 minutes, then move on. I’ve done an engine brace this way, 4′ wide. I’ve been thinking about making some sort of move-through type heating arrangement with 230V. That would be better, but either way, it doesn’t take much space.

    I can send you some things about powder coating if you like. It’s a lot of fun, and really very easy. I can get a much better finish with powder coating than with painting, and it’s less messy!

    I would love to get into annodizing. I may try this soon. Thanks so much for your web pages! They’ve been very instructive for me!

    • gordsgarage says:

      Hi Kevin, I admit I have not done alot of research into home powder coating. I know the basics and I know of some suppliers however I have always dismissed it due to the “oven” element. I am intrigued by your use of a toaster oven and an outdoor electric grill. Perhaps this is something I need to explore for future use. I never so no to information, if you have some that may help me get thinking about the process I would love to read it.
      Glad you found the anodizing inormation useful.
      Thanks!
      Gord

      • Keven Coates says:

        Disclaimer- I am not a professional, just a home hobbiest that has powder coated large and small items with the methods described.

        Powder coating- Baking by “curing lamp”

        I don’t have room in my garage for a dedicated oven for baking my powder coated parts. I have a nice big toaster oven for the small parts, but what if something is bigger than 18” long?

        I have successfully cured larger parts without an oven with a “curing lamp” with guidance from Eastwood.com, but with making my own system. A curing lamp is nothing but a heater that heats via radiated heat, rather than convection heat as in a standard oven (well, technically a standard oven heats both ways, but you get the point). To see how this works we have to first ask ourselves “What is powder coating?”.

        Powder coating powder is nothing more than finely ground plastic, that’s made to electrostatically cling to something (as plastic does). When the plastic is baked, it flows around the part, and when cured, forms a great barrier for moisture and abuse. Specifically, powder coating is plastic coating your part. They sell many different kinds of powder coat (plastic), but most of it is all similar in that it’s plastic, designed to melt onto the part and form a barrier that way.

        My theory is that the standard 15-20 minutes of baking is just to make sure it’s all flowed out as evenly as possible, and that theory seems to be verified by several others and myself who have done what could be called “incomplete” baking of powder coated parts where some parts of the object to be coated have been completely baked for 15 minutes and some have not, but the whole coating seems to be the same durability. I never hear of incomplete baking causing powder coat to flake off. As long as the powder is glossy, and flows out, it seems to be good. I’m not suggesting that we scrimp on the baking of the part, I’m just suggesting that taking pains to ensure complete baking of every square inch is not necessary as long as most of it is good and cooked.

        The same seems to be true for overcooking. If the powder flows out, and it’s held for longer than 15 minutes (or whatever the rated time is), it doesn’t seem to have a problem with that as long as the temperature is correct. If I do one side, and the part is large enough where the other side doesn’t get cooked, and I do the other side, but that causes the first side to get hot again, this doesn’t seem to cause me problems. This has meant that sections get double cooked, but this doesn’t seem to cause problems either in durability or color.

        Eastwood.com has heater elements called curing lamps, mounted on stands to bake large parts. They say, cook the object to x degrees (usually 375-400 degrees F) and keep it there for the baking period (usually 15 minutes), then move it on to the next section and do the large parts that way. I have done this several times with good results. The important thing is to make sure the part to be coated is uniformly at the correct temperature in the area you are baking, then move on to the next section. It’s handy to be able to bake two sides at once, although not necessary. It will be more efficient that way, and will help guard against overcooking (which I have not had problems with, but could conceivably be a problem if taken to extremes).

        Curing lamps are designed to use radiant heat, so are relatively unaffected by airflow (although it should always be minimal with powder coating so that no powder is blown off the part before it cures). To make my own, I used an electric grill, the really cheap kind like this http://www.gas-grill-review.com/image-files/electric-bbq-grill.jpg . I got mine from a Salvation Army type resale shop for $2. Get two if you can. I then threw away all the parts except the heater, cord, and reflector.

        Now I have a nice heating element with an aluminum reflector that will aim heat at my part. Then I mounted it on a stand that would allow me to move it up and down, and also sideways to some degree. To do this I used a medical I.V. stand that the neighbors were throwing away. This is simply a four wheel base with a tube going up that’s adjustable up and down. Then, on the stand, I mounted a gooseneck from an old portable CD player mount for a car. This is nothing more than a flexible neck that can be bent, and stays in position after it’s bent.

        I mounted the grill element with reflector on the gooseneck so that it can be moved anywhere I want, and the IV stand moves it up and down. This is a poor man’s version of this: http://www.eastwood.com/infrared-powder-curing-system.html#

        Put together, it looks like this:

        \ <Grill element and reflector
        \
        \~~~~~~|<gooseneck
        / |
        / |
        / |<IV stand
        |
        |
        |
        |
        _______|_______
        O O

        This works well, and seems to cook anything I want, although slowly. It will raise the temperature of any steel part next to it to 400 degrees if placed within about 5” of the grill element. The only exceptions to this rule would be larger items that have a lot of surface area (like a big sheet of steel). If there is a large surface area of the part that cannot be heated at the same time, then the heat would flow to those areas and they would act like a heat sink http://en.wikipedia.org/wiki/Heat_sink . It works great on tubular items or long parts, but wouldn’t work for large surface area parts like a 3’ x 3’ piece of sheet metal since the heat would be carried away by conduction to the areas not being heated and therefore the part would never get to 400 degrees.

        One side note: in my case the electric grill element didn’t want to stay where it was supposed to when mounted vertically, so I had to wire the element into place with some stainless wire. Regular bailing wire will work, but not last as long due to corrosion because of the heat. I used stainless “trolling wire” for fishing since it’s an easy source of stainless wire. Like this: http://www.amazon.com/American-Fishing-Wire-Stainless-Trolling/dp/B0009V0TGK

        I said get two electric grills because it works best if you use two of them, one on each side, then you can heat the sections just once, and it will go a lot quicker. For garages with only 120V, you’ll have to use two different circuits since each 15 amp circuit will most likely only take one electric grill section. The best setup would be two identical stands, each with its own element, shooting heat from both sides.

        I have gotten some electric oven elements to make a much more powerful version, and should work well with a similar setup and a home made reflector, but I haven’t tried this yet. Of course this will require 230V, or you can run it at 120V, but with ¼ the power. This may not be enough power to heat the part effectively though. I have heard of people using propane heating tank top heaters like this one http://www.amazon.com/Mr-Heater-Double-Tank-Top-Propane/dp/B00002N5W8 , however, be aware that any very high temperature systems like this pose the risk of powder explosion if exposed to a high enough concentration of powder in the air. http://www.powdercoatingonline.com/safepowdercoating.pdf has some information on this. I think for the home hobbiest, this scenario would be highly unlikely, but just be aware that the possibility exists.

        To use a curing lamp, the procedure is simple.
        1. Position the part to be coated on a hanger, with lots of space around it to place the heating stands later.
        2. Coat the part with powder using your powder coat gun, being sure to cover everywhere completely (if it looks not quite coated, it is not quite coated).
        3. Position your heating system (curing “lamp”) to heat the lowest section and turn it on, knowing that the heat will rise and pre-heat the upper sections. This will save time in getting the upper sections to temperature.
        4. Use a cheap IR temperature measurement gun like this: http://www.eastwood.com/pocket-infrared-non-contact-thermometer-522deg.html (cheaper ones can be found from various sources) to monitor the heat of the part. It will rise quickly and in ~10 minutes start to level off.
        5. Ensure that the part is heated to the correct baking temperature. Adjust temperature by getting the curing lamp closer or farther away.
        6. Continue heating the part section at the required temperature for the required time.
        7. After the required time has passed and the powder coat in that area looks good, move the part to the next “section” to be heated. Overlap sections by 25%-50%.
        8. Good results can be had by overlapping 50% and moving the lamp only half way. This way each section gets cooked for the required time, but is more evenly cooked.
        9. If you only have one lamp, after one side is done, move to the lowest section on the other side, and repeat moving the lamp all the way up. Of course, this takes more than twice as long (since the lamps will not work as fast from just one side), which is why I told you to make two systems ;-).

        That’s it. I made my curing lamp for $2, some trash, and 15 minutes of my time (once I had the parts), but then, doing things on the cheap is one of my “arts”. I have done monte carlo bars for engine bays this way, and an engine air cleaner lid, etc. These all worked great, but be sure to cover the part completely with powder otherwise the corrosion protection will not be as good. Have fun!

        Keven

      • gordsgarage says:

        Awesome Keven! I thoroughly enjoyed the read, well written! A lot of the time I think people (including myself) get stuck in a rut and believe there is only one way to do something. I try and keep an open mind and think outside the box however it is a constant challenge.

        The technique you outlined for curing the powder coatings sounds like the ultimate solution for my needs. You outlined the set up and process perfectly. I am going to add the powder coating to my brainstorming list. I have a 1400 watt infrared 110V heater that may be well suited for the project.

        I have been looking at powder coating guns and have found that there are a couple different styles out there. Some have a built in power source and others run them separate. Do you have any advice or suggestions as to what are the key features to look for in a low production home hobbyist type gun? I get some of my anodizing supplies from Caswell who also supply powder costing guns. You can view them here.

        Thanks for taking the time to send me the information

        Gord

      • Keven Coates says:

        Thanks for the Kudos. And you’re right, it is always a challenge to think outside the box. if it was easy, everyone would be doing it!

        The 1400W IR heater sounds perfect. Anything that can heat something up to ~400 degrees F. that is light enough to be positioned in the right positions will work well.

        As far as guns here’s what I know (of the cheaper range of guns out there):
        The harbor freight $60 (on sale) gun
        The Eastwood $100 gun
        The Caswell $230 (US price)
        ^These all look the same, except the power supplies are different. I like the power supply on the variable ones, since they say that the powder, if charged too much, can repel itself, and so doesn’t get into the recesses (like the inside corners). I can verify that there are times like this.

        The Harbor freight one does not have a variable supply (although some say it can be modified to have it) and this is the one I use. There are specific places that it just won’t coat. I’m not sure why this is, but overall it does a fine job most of the time.

        Among the power supplies, besides the benefit of being variable, some may be more reliable than the others. Really they’re probably all just electronic neon power supplies that have been adapted to powder coat guns. The only requirement is a DC voltage output of 8KV-50KV to charge the powder and make it cling to the part (which is grounded with a wire. Unlike charges attract, so the grounded part attracts the powder).

        Among the powder flow through the guns there can be little difference; they all (in this price range) look and work the same as far as how the powder blows through the gun. What may be different is the way the powder is charged. This is critical.

        In the HF gun, there are little electrodes inside the gun that charge the powder. They are small and pointed, and at times get too much powder on them to effectively charge the powder blowing by. In this case, the powder just fogs the part, but doesn’t stick, since it’s not charged. Blowing out the gun with compressed air will solve this, but it’s not something that should need to happen as often as it does. Some days are worse than others, and some pressures are worse too. Keeping up a higher compressed air pressure will prevent this somewhat, but then you’re wasting more powder since there’s too much coming out of the gun at once.

        I have no experience with the other guns, but people say the Eastwood one is better than the HF one (less overspray). I haven’t heard about the Caswell gun.

        The gun’s job is simply to charge the powder and fog the part to be coated. The problems are:
        1. Reliably charging the powder with electrostatic charge so it sticks. If all the powder was charged, all of it in the vicinity of the part would cling, but this is not the case. There is always some overspray. Also, as I mentioned above, the HF gun (the only one I’ve tried) can clog up and stop charging any powder, then non of it sticks. It is easily cleaned, but this is a pain.
        2. Reliably discharging powder. This doesn’t seem to be a major problem, even in high humidity environments like Houston on a hot summer 90% humidity day. I’ve had it clog once or twice, but it’s never caused me much of a problem.
        3. Distribute powder evenly in the discharge pattern. It’s got to fog in the right direction. The tip on these guns ensures a general fog, but it’s purposely not very directional. There are times when you want it to be more directional, and then you have to change the tip and sometimes it’s hard to get the area coated that you want. Variable charge may help here. Maybe what I thought was bad discharge distribution is actually the powder being too charged and not going into the recesses?

        The good part is that there’s no way to get too much powder on something. At least with the HF powder coat paint (all I’ve used), excess paint will not stick. Coat it all as heavily as you can and then bake it. If you can see metal through the powder, it’s not thick enough.

        As a side note, there are two really great things about powder coating:
        1. It’s a plastic coating the melts and then hardens in place. It’s not a paint, that has to harden by outgassing. When paint hardens, microscopically the solvent must evaporate out of the paint, leaving micro pores that let water and moisture get in. This is why two coats of paint are better than one, but still the paint coating is not as thick as it looks. Because of these micropores, much of the paint thickness is not useful since in the area of the pores, the paint is thinner. Epoxy paint gets around this, but is a real mess to use and clean up.

        What this means is that if the powder coat plastic will stand up to the environment (if it’s sunlight, which means UV stable, etc.), then the corrosion protection will be outstanding compared to any non-epoxy paint.

        2. It’s immediately hard, and melts uniformly to make a fantastic shine. I’ve never achieved a paint job like I can powder coat. It’s too hard for me, but the shine and uniformity of powder coating is outstanding, and much easier than paint. Plus it’s immediately hard once it cools. There’s no month long “soft” stage like most enamels (nearly all spray paints), and it’s very durable.

      • gordsgarage says:

        Again Keven, fantastic information! You layed it all out very well, I suspect it would have taken me a month of research, and mistakes, to figure out what you just told me. I was reviewing all the guns you listed for comparision sake. A question I have is in regards to the variable voltage. What is the point of having adjustable voltages on the power source? I downloaded a manual for one of the guns to try and determine how to properly use the voltage. In the manual it states to start off at the loweset setting, when turning on the power, and then crank it up to maximum voltage. Are you able to shed any light on this?
        Thanks again!
        Gord

      • Keven Coates says:

        I have not tried the variable output guns, but here’s what I’ve heard. If the powder is charged too highly (higher voltage) the powder particles may repel each other in the air. Normally this would only cause the “fog” to spread out, which is not a problem, but try coating the inside corner of a cube. In this situation, the particles repel each other and don’t want to get to the actual metal for some reason. I’ve tried this and I can verify that no matter how much powder I shoot at certain places, it just won’t coat. It’s been a while since I had this problem, so I’m not sure if they were all inside corners or what particular shapes I had trouble with.

        Supposedly if you lower the voltage on the gun, this problem goes away. Why not just use a lower voltage all the time? I suppose this would mean less powder would stick to the part overall, since the powder discharges in the air to some extent, and if it discharges too much before it hits the part, it won’t stick. The rate of discharge depends on the humidity of the day. That’s my theory, but I’m not completely sure it’s true.

        For the above reasons I think it would be valuable to have a variable power supply, but I have no first hand experience with it. I do know that there are some areas that my gun just doesn’t seem to want to coat no matter what. It may have had to do with cleaning, or it may be the inside corner problem with the voltage.

      • gordsgarage says:

        Hey Keven, I think you are right on the money with explanation of the variable voltage supplies. It also makes very logical sense. I have since found more information that backs up what you explained in regards to highly charged particles repelling one another making converage in crevices and corners difficult.
        You have certainly peaked my interest with all of this. I think powder coating is well worth my time, and money, to experiment with. I always complain about being able to properly finish projects. Now with the ability to anodize, combined with my paint booth, I think adding powder coating to the repetoire is the way to go. It may not happen for awhile but that’s how I operate. I work in layers and have lots of projects and improvements, all at different stages, all going on at the same time.
        Thanks for the fantastic tutorial
        Gord

      • Keven Coates says:

        Thanks for the confirmation. I’m an electrical engineer, and a friend suggested a way to make the Harbor Freight gun variable voltage, so I may try this sometime and see how it works. I’m also very interested in trying out anodizing. I’ve read websites about it before, but your process seems simpler than most, so it got my interest as well. Another thing you might want to add to your repertoire is plating. I bought an old Logan 11″ lathe a few years back for nearly scrap value, and spent a year rebuilding it in my spare time. The hand wheels were rusty from sitting in the rain for a few years, and I wondered about the best way to get them restored and rust free. Paint would surely chip, and even powder coating might chip with my class ring banging against it, plus I wanted it to look nicer than paint, so at the encouragement of another lathe guy, I tried the Caswell plating copy chrome (with a copper plate under). With just a little work, it turned out very nice. I was really impressed. See the results at http://s578.photobucket.com/albums/ss228/kevenc/My%20new%20Lathe/#!cpZZ2QQtppZZ24
        under “rebuild pictures”.

        I spent less than $80 by just buying chemicals because I already had the power supply. I did all the knobs and hand wheels, and I’ve got lots of chemical left over.

        I’ve built the stand, but am in the process of finishing it. I am bracing the legs and adding metal tool box drawers and a cabinet for underneath.

        “It may not happen for awhile but that’s how I operate. I work in layers and have lots of projects and improvements, all at different stages, all going on at the same time.” Sounds exactly like me! You and I are very similar in many talents and methods, although you have an artistry to your work that I strive for. Keep it up and I’ll follow your progress!

      • gordsgarage says:

        Hey Keven, if I can help you out in anyway with an anodizing just let me know.

        The photos of the lathe rebuild are great, I checked them all out. You certainly took it a long ways from what you started with. It’s nice to see you were able to give it a second chance at life. Nice work with the plating as well. I have looked into the plating process in the past, eventually I may sink myself into into it. Caswell is a great resource to have as a home hobbiest.

        Keep me posted on your projects, I would love to see what you end up spinning on the new lathe.

        Thanks for the powder coating education, I’ll try and do you proud in the future with some coated projects.

        Cheers!
        Gord

  7. OK Kevin you peaked my interest. Where in Houston are you? I’m up here in Willis.

  8. just comment for support great article.. thanks (y)

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