ShopBuilt - How to Anodize Aluminum!

Battery acid is 37% sulfuric acid, 63% water, in case anybody's wondering, so by diluting it 3:1, you end up with about 9% sulfuric acid. You could also buy undiluted sulfuric acid if you wanted, and dilute it 11-1. Also, aluminum anodization is just creating a very thin layer of aluminum oxide, which is a hard ceramic, on the surface. Then you dye that thin layer.

Hey, I work in an anodize shop and work with aluminum airplane parts. You mentioned using aluminum tig wire and said you can only use it once. You can etch your aluminum tig wire to remove the anodize finish. We use aluminum racks to hold the parts and dip them in boric sulfuric acid to get an anodize finish. Of course the racks get anodized as well so we just etch them in lye and then dip them in a weak acid wash to get rid of the dark etched coating left from the lye. A point: the aluminum racks do wear out from the repeated etch/acid/anodize process. They get thin and flimsy.

When diluting acid, put the water in the container first. The reaction between water and acid generates heat. Slowly adding acid to water prevents the heat being generated too quickly, which can be dangerous.

I'm a machinist and was just curious on the whole process of anodizing. Very informative and well put together. Thanks!

Back when I used to work in a plating lab, we had a collection of small plastic tapered pins that we used to connect wires to parts. Wedge in a straight wire into a hole with a plastic pin and it ensures a good neat connection and is really quick to do which is important when you are anodising hundreds of small parts all at once.

Agree, green. It's just different. Didn't think I would enjoy this video as much as I did. super cool process!

Im a level 2 plater, anodizer, eloctroplate, electropolish, and passivater. Love seeing people enjoying these processes at home! I had the joy of doing this on a large scale with 1000 gallon tanks of acid and cyanide.

For not being a professional, the commitment to learning and teaching this process is amazing.. I had no idea that t-shirt dye was the homeowners version and I have that for sure.. on top of showing and explaining how things went wrong too.. deff can put this on the jack of the trade list at least.. superb job, much appreciated!!

Great post sir! Quick and to the point. I have been machining parts for RC cars for a while now and have not been able to find a clear cut video outlining the process. Now I have so I am super stoked!

Beautiful! I see how you analyzed the process and took the best bits from Giaco's video and a couple of the comments, along with some good tips and dyes from Caswell. Folks...this is the best home-brew anodizing video I've seen!

i can't say I'll ever be anodizing, but I love anodized parts on my bike and I've always been curious how this works. Awesome coverage of the basics and how to start! Thank you!

Wow, what an interesting process. Never would have guessed how this was done. Great information.

Super informative! If I ever wanted to try this, you definitely took a lot of the mystery out of it. Thanks!

Those look AWESOME! Really proud of having helped you starting if this is the result!!!

Great vid! I did quite a lot of DIY anodizing a few years back. I know you're worried about surface finish but after I cleaned the parts and have them on the hanger... 15-20 seconds in lye solution, rinse, then a quick dunk into De-Ox/De-Smut, rinse and then into the anodize tank. That will ensure that you don't get surface irregularities. Also, invest in the Caswell anodizing dyes... They're UV tolerant and the color is ~4X deeper than with RIT. You might want to take a test part that's been anodized and dyed and lay it out in the sun for a few days... the RIT dye tends to fade. Lastly, make sure your power supply is set to hold voltage and not amperage. Doing so will allow you to see when you reach PAR (persistent anodic resistance). As the aluminum oxide grows so does the resistance. Lastly... Heating the bath won't help your anodizing, if anything it'll prevent you from achieving a good thick coating, in fact... the difference between regular type 2 anodize and hard anodize is that you chill the the bath to increase the thickness of the anodize. One way to tell if your anodize is thick enough is that the part will have a yellowish tint.

Great video! Very informative and got me ready to tackle a few projects. Thank you for taking the time to do this.

Mate that was a great how to video. Watched a lot of anodizing videos and yours is one of the best. thanks. Now it's off to the shed and get cracking.

This is one of the best produced home HOWTO videos I have seen in a while. Clear imagery, clear audio, clearly explained, and especially the post-mortem / troubleshooting samples at the end.

Thanks for explaining the process. I'm finally getting a professional finish. I'm amazed at how easy this was after I figured it out. This video was a huge help. I've always loved the look of anodizing and I'm stoked to be able to do it on my parts. It's addictive! Thanks!

Repeatability is everything... You nailed it. Love the colors.