Aluminum oxide on napkin/paper towel?

[RedShirt]

Hi there - after a couple years of gentle cleaning, decided to give my trusty 10 gal aluminum kettle a good cleaning and re-passivate. Used a small amount of oxiclean free and some scrubbing (didn't soak). Looked good, so rinsed well, filled with 8 gals of water and boiled for 30 minutes. Nice oxide layer formed.

But....I noticed that I got some gray residue on the white towel I used to dry it out. I thought nothing of it and went forth with my brew day.

After the brew, I'm not getting as much gray residue on the towel, so now I'm feeling like a noob, wondering whether there is now too much aluminum oxide in my wort. Dang it. What would Palmer do? What would you do? Thanks in advance.

 

[Build]

To condition the aluminum I think you need to boil, then heat the kettle dry, spraying mist on it while heating, then boil again. You'll always get some loose oxide to wipe off at first, but you'll be building a deeper layer. As long as your water/wort isn't too alkaline, you'll probably be ok.

 

[RedShirt]

Thanks for the response, build.