Unlike aluminum that must be dyed to a color after the anodized capillaries are built; titanium's color is determined by the anodizing voltage. I was going for a deep purple color (to me) and I found the sweet-spot to be around 16.5 volts. I had a piece of platinized titanium I use for electroplating that I used for the cathode (-), but you could use lead (or probably even stainless for that matter) also. My solution was 360ml of H20 and 40ml of sulfuric acid (battery acid solution), for 400ml total of a 10% sulfuric acid solution. Add your water first, then add your measured quantity of acid. AAA, Always Add Acid. I Kept a bunch of baking soda on hand to help neutralize any burns I might incur. It takes A BUNCH of sodium bi-carbonate to neutralize just a small quantity of acid. Wear gloves and eye protection. Wash off areas with water and DO NOT use any creams or salves that will trap acid against the skin. Do not breath the gases this produces either, its the vapors, not necessarily the gases too. I heated my solution to around 120F and when I dipped my anode (+) side parts into the mix, each piece (screw) took about 3 seconds to change color, then went no further. Magic! There is a great tutorial and color chart (although I did not follow his recipie) located here: http://www-personal.umich.edu/~bobden/bob_titanium.html
If you don't want to mess with sulfuric acid, you can always go and pick up a box of TSP (Tri-Sodium-Phsphate)cleaner from your local Home Depo or Lowes. You can mix about a tablespoon with a cup of hot tap-water to use as the electrolyte, it's great for scrubbing your walls too! You will not get the same colors as on the chart above (link), but the finish is pretty good.
I just measured 40ml of acid out with the graduated cylinder, the measured 360ml of water into the beaker (I should have used distilled water for good practice, but I just used tap water and it worked out fine).
Here is the part cleaned and ready to go right before I anodized it. Please forgive the dirty fingers, these parts were going on a dirty motor.
Here are a few images of the anodized part.
You can pick the battery acid up at any NAPA, it may be called "battery rejuvinator".
Apparently you can also get anodized colors on titanium using CO2 lasers, as Adafruit discovered here: AdaFruit Laser CuttersTitanium Grades
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