Metal finishing Q&As since 1989

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Anodize dyed

Hi
I need dye 6061 aluminium (black and bordeaux colors) but I have some problems, I am working with a sulfuric acid bath but I cannot obtain a shine surface. I believe the problem could be the conditions of the parts before the treatment. Can I use the electropolish before the anodize process?

Oscar Gutierrez
engineer - Zapopan, Jalisco, Mexico
2007

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How much shine you need? gloss value?
If e-polish is not required per print, better do not do it although it could work(i'd rather use chemical polish);
your part would be more shine if you:
1. Using chromic contained do-oxide(if allowed) instead of nitric;
2. better acid etch, not caustic;
3. the shorter the etching time (as well as do-ox time), the better.

John Hu
- Singapore
2007

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The shine after anodize will be less than what you start with.
I have never used electropolish on aluminum, so do not know how well it would work for you. The chemical polish is not an easy step, so investigate it very carefully before you make that step. At a minimum, I would send a worker and several parts to your chemical vendor for training to verify that you employee can do it and that the chemical will work on your parts. You have zero support if you choose to use a home brew.

James Watts
- Navarre, Florida
2007