Anodizing Aluminium In The Land of the Queen

Aluminium is a useful material, both for its light weight and resistance to corrosion. This resistance can be improved further with various treatments, one of the more popular being anodizing. This is the process behind the fancy colored metal bling on your cousin’s BMX bike. It’s possible to perform this in the home lab, when taking the appropriate precautions.

[The Recreational Machinist] has been experimenting with anodizing on and off for the last few years, and decided to share their process – as a “what did”, rather than a “how to”. The video is from the perspective of performing this task in the United Kingdom, as the availability of chemicals varies around the world and can affect the viability of various processes involved.

All the relevant techniques are covered, from cathode design to the hardware chosen to give the best results. There’s even discussion of the use of magnetic stirrers to prevent bubble marks, as well as proper cleaning processes to avoid unsightly blemishes from fingerprints or other contaminants. Perhaps the most useful tip provided is that using specific anodizing dyes does give the best results, though it is possible to get by with various types of clothing dye. As always, your mileage may vary.

There’s a big difference between reading theory and seeing the specifics of an actual working process, and [The Recreational Machinist] does a great job of showing off the realities of achieving this at home. We’ve seen it done before, with different chemicals too. Video after the break. Continue reading “Anodizing Aluminium In The Land of the Queen”

Anodize Aluminum Easily

We’ve all seen brightly-colored pieces of aluminum and can identify them as anodized. But what does that mean, exactly? A recent video from [Ariel Yahni] starring [Wawa] — a four-legged assistant — shows how to create pieces like this yourself. You can see [Wawa’s] new dog tag, below.

[Ariel] found a lot of how to information on using sulphuric acid, but that’s dangerous stuff. One web page we covered years ago, though, discussed a safer chemistry. The process requires lye and a common pool chemical used to decrease pH. Sodium hydroxide isn’t super safe, but it is much less problem to buy, store, and use than battery acid.

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I got 99 volts and my anodizing’s done!

anodizing-titanium-with-coke

[POTUS31] had a need for anodized titanium, but the tried and true “submersion” method was not going to work out well for what he was trying to do. In order to create the look he wanted he had to get creative with some tape, a laser cutter, Coke, and a whole lot of 9v batteries.

His Ring-A-Day project has him creating customized rings based on reader feedback, and lately the requests have had him searching for a good way to color metal. Anodizing titanium was a sure bet, though creating detailed coloring on a small medium is not an easy task.

[POTUS31] figured that he could gradually anodize different areas of the ring by using laser-cut tape masks, allowing him to selectively oxidize different portions of his creations as he went along. Using the phosphoric acid prevalent in Coke as his oxidizing agent along with a constantly growing daisy-chain of 9-volt batteries, he had a firm grasp on the technique in no time. As you can see in the picture above, the anodizing works quite well, producing vivid colors on the titanium bands without the need for any sort of dye.

[POTUS31’s] favorite color thus far? A rich green that comes from oxidizing the metal at you guessed it – 99 volts.

[via Make]

How anodization is used to make pretty iPod colors

What do those colorful iPod Nano cases have in common with sapphires? In both substances the color is not on the surface, but integrated in the structure of the material. As usually, [Bill Hammack] unveils the interesting concepts behind coloring metal through anodization in his latest Engineer Guy episode.

We’re not strangers to the anodization process. In fact we’ve seen it used at home to change the color of titanium camping utensils. [Bill] explains what is actually going on with the electrochemical process; touching on facts we already knew; like that the voltage range will affect the color of the annodized surface. But he goes on to explain why these surfaces are different colors and then outlines how anodized metals can be dyed. That’s right, those iPod cases are colored with dye that will not wash or scratch off.

Pores are opened when the aluminum goes through anodization. Those pores are filled with dye, then the metal is boiled in water which closes them, sealing in the color. Pretty neat!

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Anodizing and dyeing aluminum without battery acid

While many people have tried their hand at anodizing aluminum at home, there are plenty who would just as soon leave it up to the professionals due to the highly concentrated sulfuric acid required for the process. [Ken] started thinking about the process and wondered if there was a way to get comparable results using chemicals that are easier to obtain and dispose of.

Through some experimentation he found that sodium bisulfate (NaHSO4), which is a sodium salt of sulfuric acid, can easily be used in its place with great results. The chemical is typically advertised in hardware and pool stores as “Aqua Chem”, and can be had at a very reasonable price. When paired with the proper DC current along with a cathode, the sodium bisulfate easily anodizes an aluminum workpiece and renders it ready for coloring with RIT, readily available cloth dye.

We were impressed with the results, and when looking at [Ken’s] test pieces, it seems that the metal dyed with sodium bisulfate has a more uniform, less streaky coloring to it. It’s also worth mentioning that [Ken] has found it is fairly easy to etch the aluminum before anodizing using a solution of sodium hydroxide, which is great for individuals who prefer a more matte finish.

If this is something that interests you, be sure to swing by his site. He has a posted nice video overview of the process that may be of some help.