How do you know if an aluminum pot is ruined?

I recently bought a turkey fryer and 10g pot off of craigslist. I'm concerned that the pot may not be suitable for brewing because it has marks and stains in it that won't come off. They're black, you can't feel them. I've scrubbed the hell out of them and they don't come off. I guess I could use my Dremel with a wire brush to get them off, but I've always used the philosophy that if I can't scrub it off, it won't come off in my food.

Should I use this pot, or is it no good for brewing?

 

Boil some vinegar in it, 2-3 gallons of it, diluted to fill the pot. Then refill with fresh water and boil again. Anything that hasn't come off by then, won't.

 

Hmmmm, I'll try that and report the results. Thanks for the advice.

 

Aluminum will turn dark when it oxidizes. If it doesn't come off with a light scrub with a soft cloth and nothing darkens more when you boil some clean water in it, then just call it good and brew with it.

 

If if won't scrub off, get some sand paper. It WILL come off.

 

Don't do this.
It's a metal pot. Metal oxidizes and turns dark. Aluminum does so fairly quickly, and if you scrub off the oxidation, it'll just come back.