Some anadozing questions - Green?

[Don Robinson]

I got a nice bright green on a small folder I finished a few weeks ago.

Here's the key:

Ti reacts with air immediately. If you let any of the parts lie around while you're polishing the rest, they won't even be the same color sometimes after anodizing. This is especially true if you leave some or all parts exposed to air for days before anodizing. Any exposure to air causes an invisible oxide film to coat the part immediately. That film is always there, and your anodizing film simply builds up on top of the original air oxide film.

I've found the best way for me is to give each part a final polish, then drop it into a pan of water before polishing the next part, then drop that part in the water, continuing until all the parts are freshly polished.

When all parts are ready, I hang them all at the same time on a Ti hanger, seperated as much as possible, and start anodizing. By adding voltage slowly and watching carefully, you will get green.

I use a light solution of TSP, but I don't believe what you use makes much difference as long as it makes an electrolyte solution.

So my advise is to polish immediately before anodizing, and drop all parts in water immediately to prevent a heavy oxide coat from forming. The thicker oxide coating prevents your being able to predict the color.

[Tom Anderson]

Sounds like I've got some new avenues to explore.

Thanks Kelley & Don!

[Kelly Carlson]

I think Don's explanation of the speed of oxidation is correct.
I get best results when I go from a quick etch, directly to a quick dip in distilled water and then into the electrolyte solution, with only a second in open air between the solutions.

[Tom Anderson]

I tried the high voltage green on a pair of overlays today and totally toasted them.

I'll try the "sneak up on it at around 70 volts" later on.

[Kelly Carlson]

Sory to hear about the toast, Tom.
Since losing my satellite modem last week, I haven't been able to
post any photos on CKD, but will try to email directly to you a few photos of the greens I have been able to obtain.

[whv]