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topic 60498

Can etched & de-smutted parts be delayed before anodizing ?

August 9, 2017

Q. Hi Everyone,

I understand it's best to proceed from cleaning through to anodizing without stopping between steps, but IF it's necessary to delay getting the parts into the anodize tank after rinsing from de-smutting, can the parts be held-up for an hour ?

If so, what's the best way ? Keeping submerged in a clean tank of DI water ?

Thanks in advance !

Phil Nelson
- Adelaide, Australia


August 25, 2017

A. The parts will be fine in a clean tank of water for an hour or so. I have pulled racks to add or remove masking and then entered anodize. I will do a drop in a final rinse first to verify I still have a clean water break free surface on all parts.

Ryan Underwood
precision protective coatings - Savannah, Georgia


August 28, 2017

thumbs up sign  OK, thanks Ryan.

Phil Nelson
- Adelaide, Australia

simultaneous
August 25, 2017

I wanted to add to this:

I may depend on the specific alloy of the part(s), I had a batch of sheet metal parts that were supposedly 5754, that developed light spots (0,5 mm diameter, like 3-5 mm apart evenly across all surfaces) if they were held in rinsing tanks for longer than 8-10 minutes after short caustic etch, rinse, rinse, desmut (nitric/sulfuric), those spots did anodize and dye black, and didn't leach any dye after seal (acetone wipe), but were quite noticeable, and didn't go away even after stripping and re-anodizing. This was one particular batch of those parts, same supplier, same parts, different batch could be held in rinse for 10-15 min no problem, so it might have been just a bad batch of sheet stock from the mill. Normally I hang them on Ti racks, but switching to Al racks didn't solve that problem with that particular batch.

Haven't had any problems like that with any other materials. I did however once had an issue where etched and desmutted 6061 parts were left in clean rinse water overnight, they developed irregular pits on the surface, but since the parts were blasted with something before they arrived at my place, it might have been related to some contaminants embedded in the surface.

Janis Ziemelis
- Riga, Latvia


August 26, 2017

If I were you, I don't prefer even DI water. If flight bar dwells (long or short time, 10-15 min./3-4 hour) in bath (clean or dirty doesn't matter) corrosion risk will be highest, probably you will see spots like "snowflakes".

alaattin tuna
- TURKEY,sakarya



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