Aluminium Stockpots Going Black on the Inside

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Permalink Reply by denimglen on July 16, 2009 at 3:56pm

Did that happen with straight water? High chlorine in your water or something maybe?

I'd try to get rid of it. I'd look at a mild acid to clean it, maybe a boil with some white vinegar.

The alu should build a 'protective oxide layer', this will stop any off flavours or reactions with mild acids. As long as you're not cleaning it shiny bright you will be fine.

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Permalink Reply by Nick T on July 16, 2009 at 4:27pm

Thanks for the reply. Yes it was straight water, Christchurch tap water (comes from deep artesian bores, very clean) so no chlorine and very low on any other elements as well. Had a bit of a boil with white vinegar in the water today, has taken a small bit of the black off the bottom of the pot but not much else. Some of the posts on other sites seem to suggest that the black is is the protective oxide layer, and that it should be left in place, others suggest that you should condition your aluminium with heating prior to boilng in it. Unfortunately a 32 litre pot does not fit in a normal oven to do this!

I will give it a mild scrub and try a reboil tonight I think.

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Permalink Reply by denimglen on July 16, 2009 at 4:50pm

Passive oxide layer should be a dull silver colour I believe.

Maybe give it a scrub down with a scotchbrite pad or similar and just put the smallest ring of your burner on and let it sit on that for a few seconds?

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Permalink Reply by James P on July 16, 2009 at 5:15pm

I have a 30 year old aluminium pot that I use to boil CHCH tap water to sterilise some equipment. This pot is used for all my pickles etc, and has the black surface where the water was. It seems to have had no effect on my cooking! (And no my cooking wasn't bad to begin with! :) )

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