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.
Aluminum naturally forms an oxide layer on its surface when exposed to air. Anodizing in an electrolytic cell creates a thicker oxide layer that makes the part more resistant to corrosion and wear. It also presents a porous surface that will easily take dye, leading to the bright colors you often see on anodized pieces.
In this process, the lye is used to strip the surface. Then it’s on to anodization in a solution of sodium bisulfate, with a repurposed 12 V, 2 A power supply putting a bit of current through the piece. The trick is to realize this is anodization, not cathodization. Chemically, this is the sodium salt of sulphuric acid, and you can dispose of it safely after neutralizing it with baking soda. Rit dye can provide coloring.
Overall, this is a good trick to anodize with nothing more than a trip to your local home improvement store. And [Wawa] got a stylish dog tag out of it. Win, win.
If you have some titanium you want to anodize, we got you covered.