View Full Version : Home brew anodizing?????

09-25-2003, 10:25 PM
Has anybody had experience with doing this at home?I hate to buy one of those kits only to find out that its a bunch of stuff that I already have,any help?

09-25-2003, 10:30 PM
Yep, it is a bunch of stuff you already have. Wait while I find the link.

Here it is. It's not hard. Done lots.


[This message has been edited by Evan (edited 09-25-2003).]

09-25-2003, 11:07 PM
If I can do it, anyone can. Success.. 99% of the time. Most failures occur on the connection to the dc bus to the part.

I have been using aluminum Mig wire, bend hooks and force wire into a tapped hole or small hole.

I use battery acid diluted with spring water.

I made a dye heater from a 120 volt water heater element welded to a angle iron I clamp to the dye bucket, plug it in, it heats. when hot enough I unplug it. cost $7

The plastic buckets with the lids were the main expense of my 5 gallon anodizing outfit.

I used a small supply the first time, used my dc welder set to a low amperage the next 4 or five times. Now I am putting together a hobart battery charger system to use. AS long as the dc power makes the sulfuric solution boil slightly it is okay,

DO not put any metal in the tank that is not aluminum or titanium. It eats it away. I put some parts in with stainless bolts, they got gone.

09-25-2003, 11:15 PM
Did it also....did have some pitting of the aluminum, possibly due to impurities, don't know.

Nice gray finish, has held up OK too.

09-25-2003, 11:55 PM
Great link Evan,Thanks!

Alright,the power supply,I am assuming that the car battery is being used for the purpose of providing low or no ripple dc right?I was wondering if this is the case, since I have some huge(40 amps @ 45volts) plastic capacitors out of an edm machine would these be just as effective?

09-26-2003, 12:38 AM
It really doesn't seem to matter if there is ripple or not. Car battery or battery charger will work just fine. I use a battery charger with a large filter capacitor. What really matters is clean metal, no grease, clean metal, good finish, clean metal, anodizing won't hide squat. Did I mention clean metal???

09-26-2003, 02:15 AM
On the dye thing on that link I posted. I have been able to achieve deep black using ordinary fabric dye if it is mixed about four times stronger than recommended. I also have added some inkjet dye to the mix. The first time I anodised a part I took the advice to heart and supposed I would not be able to obtain a true black. So I used a deep blue dye, a royal blue. I was hoping for at least a deep blue. I let the parts sit in the dye at room temp for about four hours and they came out jet black. OK, fine by me. It does depend on what alloy you use. Cast aluminum will not anodise well, be warned.

09-27-2003, 12:10 AM
Rit liquid dye, has a acid base I think.. You want the kind that dyes wool.. It works great..

Shades are differnet then the cap thou.

I heat mine to about 200 degrees... soak about 20 minutes or to desired shade.

THen boil in stockpot (clear water) for about ten minutes. So far it has worked.. except for the red, it dissapears in sunlight, no clue why..


[This message has been edited by ibewgypsie (edited 09-27-2003).]

09-27-2003, 12:33 AM

Red has always been suceptible to fading in ultraviolet. It's the worst color possible for a car since it fades so bad, aside from being a cop magnet.

Say, 200 is a little too hot I think. That will start the sealing process too soon. From what I have read and tried about 140 is best.

[This message has been edited by Evan (edited 09-27-2003).]

09-27-2003, 09:15 AM
Hey wierd
I found this link a while back and have started to collect items to start the anodizing process. Lots of pictures and information. Good luck & let us know how it goes. http://www.focuser.com/atm/anodize/anodize99.html

[This message has been edited by rockrat (edited 09-27-2003).]

[This message has been edited by rockrat (edited 09-27-2003).]

09-27-2003, 10:00 AM
Thanks for the link,I'm going to make an attempt next weekend,right now the biggest obsticle is finding clean five gallon puckets http://bbs.homeshopmachinist.net//biggrin.gif

09-27-2003, 10:22 AM

AS I said,, the home dupot had the clean buckets at 3.95 each, plus lids. The largest cash outlay in my system. The electrolyte was I think about $8.. the aluminum bus (I plan on cutting a battery apart for the lead plates) for the bottom of the tank was scrap, the aluminum mig wire came off a spool gun because of splatter burns.
You need a good etch solution, I use Red devil lye solution it makes the aluminum boil. Then be sure to rinse, make sure the rinse water is clean rain water, not tap.. I then go to the electrolyte and DC bus boil for about 20 minutes. If you boil it too hard, it heats the acid up and eats away the finish as fast as it accumulates.. The surface is actually harder then the base aluminum.

I wonder why people don't do pistons. It would build a small coat up to tighten tolerances. That and knurling would possibly allow you to put some wore ones back in and run some more. (2 stroke racers)

Fingerprints show. I put all the parts on the bus and use it to dip, leave the aluminum wire long enough to wrap into a bundle and hook to the Plus of the supply. The few failures I have had was from the parts coming loose during the electrolyte bath. ALso, some cast parts anodized unevenly, but still looked better then they did.

Thanks Evan, I will reduce the seal time and tempature to play.. So far I have really positive results, Mostly from advice from this board..

So, process is.
1) dish soap wash,
2) rinse
3) etch
4) rinse
5) electrolyte anodize
6) rinse
7) heat dye and color
8) rinse
9) seal in boiling water
10) rinse
11) use part...
Clean parts anodize well, scratches show, imperfections show. A matt finish can be made with steel wool.

Wear gloves and goggles at least, have running water close at hand. The acid is dilute but.. the lye is just as dangerous.

Cheap coatings....

09-27-2003, 12:37 PM
To really degrease the part I soak or spray with Easyoff oven cleaner. That really works well. Another way to get a matt finish is to sand blast with river sand, or sandbox sand. If you sandblast the part it will require more current because of the increased surface area.

As Ibew said, after cleaning, good electrical connection is the most important thing. I use 12 guage aluminum electrical wire. Go ask an electrical contractor for some scrap cable. They always have some and it is pure aluminum. Mig wire is a bit small for larger pieces and is an alloy.

When you connect the wire to the part it must be absolutely tight. The best way is to use an existing threaded hole or make one. Shape the wire to fit (double over or whatever, hammer it etc) and wind it into the hole like a screw. Electrical wire is so soft it won't hurt the threads.

The cathode plate can be roofing aluminum flashing or lead plate. It should be similar in size to the work or larger. If the acid bath gets above room temp it must be cooled. I have used an ice bath, set the pail in a larger tub with ice and water.

If you are doing a large piece it will suck a lot of current. you can reduce the draw with a light bulb in series. A brake light bulb should work. If so you will need to increase the time. I usually anodise for at least 45-60 minutes. This is the secret to getting a true black finish which is what I usually am looking for.

Keep in mind that the part will "grow" by about .0015"

I also boil for at least 30 minutes. Make sure the part stays completly under water when boiling or it will mark.

I do all this outside to avoid problems with fumes. I use a Coleman camp stove for the sealing boil.

A good source for pails is the biggest resturant in town or an ice cream store for smaller ones.

You don't have to use the lye solution if the part is super clean.

For disposal I mix the lye with the acid to neutralize each other, carefully! Boy does it make a cool looking foam! The aluminum dissolved in the electrolyte comes out of solution and the bubbles are silver. Don't do this inside!

If for some reason (bad connection) the anodizing fails you can strip the part in the lye solution for about an hour and re-anodize. Also, as mentioned before, the anodizing bath is handy for removing broken taps from aluminum.

One more item. For a final finish wipe the part thoroughly with plain old lanolin, then wipe it off. It actually enters the micropores of the aluminum oxide crystals even after "sealing" and additionally seals the work. It looks better too.

[This message has been edited by Evan (edited 09-27-2003).]

09-27-2003, 08:02 PM
Okay,the rain water,I don't keep any around,too many mosiquitos,would well water assuming its soft work?

09-27-2003, 10:34 PM
The water must be mineral free. You could use the reverse osmosis water they sell in the grocery stores. I use rain water. Kill the mosquitoes with one drop of liquid dish soap in the rain barrels. We also put a gold fish in each of the barrels to eat the larvae. (five rain barrels)

09-27-2003, 11:58 PM
Get distilled dionized water if possible. Bottles water is not neccessarily mineral free - distilled water is. Reverse osmosis does nto remove minerals in solution. Rain water can also have contaniments.

If you want consistant results, you need to remove the variables - get distilled water (dionized distilled water if possible) - trust me.

I stake my sisters meatloaf on it (makes great anvils). http://bbs.homeshopmachinist.net//biggrin.gif

09-28-2003, 01:59 AM
Reverse osmosis does so remove minerals. The cations are too large to pass through the membrane. It even removes sodium. RO water will work just fine for anodizing.

09-28-2003, 09:43 AM
Reverse osmosis removes minerals fine in general.

The big local manufacturer of pisswater....Anheuser Bush....uses it to purify their water before brewing, and for sure there isn't any mineral or other taste in THAT.............. http://bbs.homeshopmachinist.net//biggrin.gif

And, for rainbarrels, just put a screen on top....no skeeters, no roof junk, no problem.

The dehumidifier in your shop will produce fairly pure distilled also.

09-28-2003, 10:00 AM

You use clean water one time, it is contaminated. Rain water is cheap. Relative clean is clean enough for my process. It works.

No problemo..


09-28-2003, 10:39 AM

Now, WTF didn't I think of that??? I scored thirty feet of 36" wide stainless steel screening from the local surplus store a few years ago and used it to re-screen the sliding screen on the door to my deck. Got it for $1.00 per foot. This stuff must of orignally cost 100 times as much. I'll have to make some covers for the barrels. Damn, I feel stupid. http://bbs.homeshopmachinist.net//redface.gif

BTW: Dehumidifier!! Not here! We do everything we can to put some humidity in the air. Unlike all you poor suckers on the east coast this is a semi-arid climate. I've been to Virginia in the summer. Uugg. Sweat a lot. Here, no tool rust, never even think about it.

[This message has been edited by Evan (edited 09-28-2003).]

09-28-2003, 06:30 PM
I never tried real anodizing. But if i wanted a good job, i think my first try would be with distilled water.

If it came out well, second try would be local water. Add one variable at a time until you know how sloppy you can be and still do the job.

The trial anodizing I did was with artesian well water and Rit dye. THe result has been laying in the weather for over two years, the dye faded, the part is un-corroded, a un-anodized "test" part is corroding a little, a aircraft JIC fitting still looks like new. The well water is a long way from "pure". Can't conclude much from a sloppy test though. The acid was from a car battery, so it was not pure either.

I can only conclude that some protection was afforded even as sloppy as I did the job.

09-29-2003, 12:54 AM
He he. Most of my work is intended for use outside. Hah, but at night in the dark. Should take a fairly long time to fade by starlight. http://bbs.homeshopmachinist.net//biggrin.gif http://bbs.homeshopmachinist.net//biggrin.gif

09-29-2003, 08:44 AM
Hope you guys use a diverter valve to let the rain wash the bird **** off the roof before filling the barrel http://bbs.homeshopmachinist.net//biggrin.gif Oh and the screen would work great to keep dead pigeons out of the barrel too http://bbs.homeshopmachinist.net//biggrin.gif

09-29-2003, 11:22 AM
If you have good soft tap water it will work fine. I would test it with a ph test kit. If it is neutral or even slightly acid then it should be fine. If the ph is over 7.5 then forget it. Also, if you have iron stains from the tap water then forget it.

As for the bird ****, oddly enough, some organic compounds like urea actually help the process. Try talking to an old hand electroplater and ask him what he uses in his solutions. Fat chance he will tell you. It is rumored that piss helps get a smooth job.