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Coloring Titanium

A friend of mine is putting Titanium bolsters on his knife for the first time. (We are knifemakers.) He has gotten a blue color to it simply by putting electric current through it. I was of the notion that it needed to be in a bath (electrolyte,..something..Anything?.) in order to control the color phases. So does anyone know how --or where I can get information to do this?

Gene Hughes
- Mancos, Colorado
2001

Actually, Gene, anodizing titanium alloys to get pretty colors is rather simple. When my son was in 4th grade, he took the Chemistry section and almost won the overall prize in his school science fair with a project on using different electrolytes to color titanium.

Of the four solutions he used, he preferred the TSP [trisodium phosphate ⇦this on eBay or Amazon [affil links] ] over the table salt, the lemon juice, and the baking soda solutions, although they all worked well. Steve got the 24 volts he needed from four 6 volt batteries, and the CP titanium he used colored almost instantly. He felt the TSP gave a deeper color, but it might have been a trick of the light.

Bill Seeley wrote a couple of articles for Metal Progress and JOM in the early 80's, and one of his articles showed how the color is dependent on the voltage used. Heck, buy a bunch of batteries and check it out for yourself- it's kinda cool, and with a small setup you'll be able to paint the colors on.

A good start is wuarchive.wustl.edu/edu/arts/metal/TOC/finishes/anodize.html [Ed. note: sorry that link is no longer functional], which is an article by the above mentioned Bill Seeley. Next, do a Google search on "titanium anodizing" and you'll find lots of folks who share your interest.

Good luck!

Lee Gearhart
metallurgist - E. Aurora, New York
2001