I just came across this while doing a search on woodturning of all things (going to make some nice birds eye maple rims
) and i thought this may be of intrest. I was too lazy to read it all but it looks quite comprehensive.
http://www.focuser.com/atm/anodize/anodize99.html
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http://www.focuser.com/atm/anodize/anodize99.html