I don't offer any of my stuff anodized but I have had a number of questions through the years about anodizing titanium and I have been meaning to take a quick video demonstrating how one might color their light or other titanium part. I just built a Ti UV light for myself because I let one of you talk me out of my UV PD. I wanted to make this light obviously different than the many white LED lights that are always laying around and I have used anodizing on some other lights to identify them as something other than "white".
In the video, I also anodized a Ti-20 clip. The items seen in the video are these:
I uploaded the video to YouTube, HERE.
This thread can go anywhere you guys want it to including down into the dregs of ignored CPF threads.
I would add that I think the clear oxide film of titanium along with the other refractive metals is fascinating in itself and how you perceive color by virtue of light waves interfering with each other and not due to the absorption of some of the spectrum and reflection of the balance.
I consider anodized titanium for the most part to be a cosmetic feature and unless the anodized surface is reasonably protected or recessed, the film can and will abrade over time and show this wear. On the other hand, there are some situations where having the option of coloring a part does give you means of identification, beyond cosmetics.
In the video, I touched on the point that when you anodize titanium, you don't want any other metal in the bath and part of the electric circuit. If there is another metal. It typically just bubbles away in the bath in that area and you don't get a good film growth on the Ti surface itself. I have used this feature in the past to confirm the claims of some items I bought which were stated to be "all" titanium. In many cases, the claims were false. It's probably silly but for me, there is a certain pride in purity in the fact that I can take one of my titanium lights, as is and even turned on, and throw it in an anodize bath and have it change color uniformly in all exposed surfaces. If you take the light apart, you can see where the seals sealed and there is no anodize color beyond.