Is it because the metals are different?

[mj1angier]

I am building my 20 gallon BIAB electric pot. I got a new SS pot and was going to use the basket out of my aluminum Bayou pot. Got everything drilled and wired up and was giving a test run to check seals, heat...

After I shut it down I pulled out the basket and the bottom of basket is turning black.

Is this because of a problem between the SS pot and Alum. basket? I did the boil with some PBW to help clean out any left over machining oil.

 

[SleepyCreekBrews]

I put some 2-stroke motorcycle cylinders in the dishwasher once and they turned black like that ....I assumed it was the dish washing detergent.

that's odd that it's just certain areas.
It could possibly be a chemical reaction from using the PBW (stripping off the oxide layer?) ...or maybe it was already gone.

I'd be inclined to scotchbrite it so it's shiny again and try again with a water boil .

 

[cswis86]

Have you used the aluminum pot for brewing before? I know that aluminum and acidic foods (like beer wort) don't mix.

http://www.thekitchn.com/food-science-explaining-reacti-73723

 

[day_trippr]

What you are seeing is an oxide layer forming on the colander.
This is not only normal/expected but desirable if you're planning on using the colander with wort production, as the oxide layer will prevent wort acids from dissolving the aluminum.

What you might actually want to do is bake or boil the whole colander long enough to turn the whole thing dark gray so it's totally passivized...

Cheers!

 

[mj1angier]

I have used it before to brew. Did about 8 batches in the old pot over a burner. It was a dull gray before.
I only had about 4 inches of water higher than the bottom of basket, but it did the black in odd spots where ever it was in water.
I will give a full fill and boil tomorrow without the PBW and see what happens.

 

[mj1angier]

Ok, filled it up to 17 gallon make and got it to a rolling boil. When I emptied it out, the sides of basket has some dis-coloration but not as bad as the bottom. I am going to go ahead and run a batch and see how it goes.