Anodize Your Own Aluminum Parts!

Have you ever wanted to add a durable, corrosion resistant protective coating to your aluminum parts? Type II Anodizing is a great option, and it's a relatively easy and inexpensive process to perform at home.
Materials and Supplies
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You can probably find a lot of these supplies at even lower prices locally. Auto parts stores typically have battery acid, and hardware stores have buckets and PPE. Craft stores have fabric dye.
** DISCLAIMER: This process involves extremely caustic chemicals, which must be handled with care at all times. Avoid direct contact and wear appropriate protective equipment at all times! Goggles, rubber gloves, apron, respirator, etc. If you are not familiar with basic chemical safety, please do additional research before trying this out. Schaner Designs is not responsible for any damage or injury caused as a result of watching this video. You are responsible for safe use and proper disposal of any chemicals that you use. **
Additional Details
I'm not a chemist, so I'm not going to go into too much detail on the underlying process, but here's a quick overview.
The cathode is the electrode connected to the negative (black) terminal of the power supply, the big chunk of aluminum in this video. Aluminum (ideally 6063) and lead are usually the recommended choices. Lead will last indefinitely, and aluminum will be consumed slowly over time.
The anode is the electrode (i.e., your parts + fixture wire) connected to the positive (red) terminal of the power supply.
The sulfuric acid is the electrolyte, which conducts current between the electrodes. As the current moves across the outside layer of the aluminum parts, a chemical reaction occurs between some of the oxygen molecules in the sulfuric acid solution and the aluminum base material, forming aluminum oxide. This reaction occurs naturally in air as well (all aluminum has some level of aluminum oxide on the surface), but it's accelerated with the acid bath and applied current.
The time required (in minutes) is determined by the following formula (called The 720 Rule), where thickness is measured in mils (1/1000 of an inch), and current density is measured in amps/square ft:
Time = 720 * (Thickness) / (Current Density)
Current density is equal to the current in amps divided by the total surface area (in square feet, or square inches divided by 144) of the parts being anodized. I found several sources that recommended a current density of 6-12 A/SF for this type of setup, so I used 12 A/SF as my target and adjusted the current output accordingly.
If you want to go into more depth, this article has some great information: finishingandcoating.com/index...
An important note on the last step - hot water sealing: As a viewer kindly pointed out, I should have been using a hot plate to keep the hot water boiling when I dipped the parts after the dye step. This is an important step if you want to maximize corrosion resistance and ensure color longevity, and I realize now that I did not give this enough attention when making the video. Reputable sources recommend a minimum temperature of 95°C/203°F held for several minutes. This causes another chemical reaction and helps seal the porous aluminum oxide layer with a crystalline material called boehmite, that is formed from aluminum oxide particles dissolved in the hot water.
If, like me, you skimped on this sealing step the first time, you can always go back and soak the parts in boiling water for 5-10 minutes before using them.
Also, here's a quick conversion table from SG (or kg/L) to % concentration for sulfuric acid: www.handymath.com/cgi-bin/sul...
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00:00 Intro
01:47 Safety Overview
03:27 Materials, Supplies and Setup
07:47 Washing and Anodizing
10:59 Rinsing and Dying
12:34 Final Thoughts

[@sadioshin471]

Thanks for the info! Will come useful later :)

[@mwinner101]

Great info. Well presented too. 👍

[@schanerdesigns]

Thanks, glad you enjoyed!

[@noviceartisan]

Looks good! And it's nice to see someone been sensible wtih safety equpiment! ^_^ I belive the final step though does need a sustained temperature for a period of time though, so maybe use a hotplate with thermometer and stir bar. The pores you've filled with the dye need to be closed to seal them and gain that hardened surface that anodising gives. If you're not holding it at temp long enough, those pores won't fully close and it'll not be fully anodised, just dyed. Al least that's my understandiing.

[@schanerdesigns]

Great catch, thanks for calling me out on that! I was under the (incorrect) impression that sealing was only important for color, but further research indicates that it's critical for corrosion resistance as well. Looks like the recommendation is several minutes at 95°C/203°F or more, using distilled or deionized water. Interestingly, there's no mention of an impact on hardness. I soaked all of these parts in boiling water again just to be safe!

[@noviceartisan]

@@schanerdesigns You want to be sealing it, at 95C, for the same to double the length of time it spent soaking in the dye. Without the complete Sealing stage, the suface will be weakened and scratch/mark easily vs when it's actually sealed. Try doing a piece properly then compare to an older piece done wongly :)

[@beepboop1569]

hey nice video! it would be super nice to see some chemistry info with it. i can obviously go google it but it would help to understand the process better. Also for example the time calculation would be handy for clarity :)

[@schanerdesigns]

Thanks for the great feedback! I just updated the description to include some more info about the chemical process and the calculations involved. I hope that helps!