How to color anodized aluminum

Aluminum How-To
"Chromating - Anodizing - Hardcoating"
by Robert Probert

Also available in Spanish

You'll love this book. Finishing.com has sold almost a thousand copies without a single return request :-)

"The Surface
Treatment &
Finishing of
Aluminium and
Its Alloys"
by Wernick, Pinner
& Sheasby

on eBay or Amazon
or AbeBooks

(affil link)

Hi, Doug.

The colors on aluminum are done with anodizing dyes, which are actually not very different than fabric dyes. First you clean, etch, and desmut the aluminum. Then you anodize it, which leaves a microminiature "honeycomb" surface on it. Then you put the work in the dye tank and the dye is absorbed into the honeycomb, then you seal it (which means you swell the walls of the honeycomb to lock the dye in place). The anodized layer is rather transparent so the dye shows through.

Typical anodizing voltages will be 12 V to 18 V depending on the alloy.

Proberts "Aluminum How To" is a very practical book on the subject ⇨
and Wernick, Pinner & Sheasby's "Surface Treatment of Aluminum and Its Alloys" is the 2-volume in-depth treatment of the subject. ⇨
Good luck.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

Pure Lye on eBay or Amazon

(affil link)

To strip anodize off any part we use Red Devil Lye. Fill up a small bucket halfway with water add 3 tablespoons of lye, let it dissolve. And Bam drop in your part. 15 minutes later. All clean

Let's say "slowly and carefully immerse your part" rather than "Bam drop in your part" :-) Remember that one drop of lye in your eye and you're blind, so goggles ⇦ on eBay or Amazon [affil link] and rubber gloves ⇦ on eBay or Amazon [affil link] are necessary. Good luck.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey