Letter 080

Minimizing bleedout from anodizing pits

-----

I own a company called REEL COLORS. We take Penn International fishing reels from around the world. Strip the existing gold anodize. Machine the scratches and pitting on our lathes and re-anodize them to match their color sample. My problem is sometimes I can't get to the bottom of a pit (pitting from salt water). Even though it is so small you can't see it without a magnifying glass, there is a good chance I'll get a bleed mark. Is there any way to prevent this? My anodizer does their best but it is a big problem. Now I'm telling my customers with badly pitted reels that they should consider going with black. I don't seem to have this problem with black. Thank you very much for your time .

Tom Testa
- Deep River, Connecticut

I'm surprised the problem is less severe with black.

I think there isn't much you can do about the pit, but you may be able to do something about the bleedout of the sulfuric acid. Ask your anodizer to try these three ideas:

 

1) neutralizing the anodizing solution with sodium bicarbonate;

2) displacing the anodizing solution by a dip in dilute nitric acid;

3) hot & cold rinsing after the anodizing.

 

The three ideas can be combined, i.e., rinse hot & cold; dip in nitric; rinse; dip in bicarbonate; rinse.

Ted Mooney, P.E.  finishing.com Brick, New Jersey