Paint mixer turned black

I bought a paint mixer to aerate my wort today and after a few hour soak in star San, I noticed it had turned black. I decided not to use it and revert back to the shake method. Is it ok to use it? I believe it's aluminum but can't be sure.

Well Star San is acidic, so I try to keep it off all metal surfaces if possible, much less soak for hours. Not sure what reaction you had going on, but I'd be leery to use it.

should reverse the process... works with oxyclean just keep an eye on it..

Soak in oxyclean? How should I sanitize in the future, just give it a quick 1 or 2 minute star San soak?

Edit: oh I think you mean soak it in star San again... Correct?

The aluminum oxidized in the acidic Star San. Similar to an anodization process, only without the electrochemical help.

That said, you should be OK. If you've ever sent an aluminum pan through a dish washer, you'll no doubt experienced the same thing. For the few seconds you're using it in the wort, you'll be fine.

Also, for what it's worth, Star San only needs 30s to sanitize. Thus, 30s or a few hours have the same result. So for future uses, just dunk in star san for a minute or so.