Chemistry question: anodised aluminium coffee pot VS dishwasher

[darrylmg]

Bin it. It's stuff off of metal that you wouldn't drink if you could see it in the water, so why would you drink it in the coffee.

[d000hg]

This link discusses it in more depth than others I've found... What happened to my espresso maker? - stovetop dishwasher coffee | Ask MetaFilter

Some speculation it actually wasn't anodised and just got a good oxidisation under the heat and alkalinity of the dishwasher, and this can be addressed at the cost of visual appeal.

[d000hg]

Should I remind you guys this isn't general?

FFS it's like a £30, pot, drop it in the bin and buy another one.

a)Bialetti pots of this size are not £30.

Any aluminium is covered with aluminium oxide very quickly - precisely because it's so reactive. Try here.

b)I have googled extensively as my OP implies. Nothing I found answers the question if the black dust is a special/different type of oxide only occurring due to the dishwasher and it will be replaced with a more stable different oxide. Some metals are prone to powdery oxidisation and as fast as you brush/clean it off, more comes back.
We anodise aluminium for a reason, isn't that reason that normal oxides are not as stable?

[NotAllThere]

Any aluminium is covered with aluminium oxide very quickly - precisely because it's so reactive. Try here.

[WTFH]

£30? Someone saw you coming!. Wouldn't pay more than a tenner for one from a market in Naples

[DimPrawn]

FFS it's like a £30, pot, drop it in the bin and buy another one.

What sort of sad contractor are you?

And PS, sack your maid, she clearly doesn't know anything about domestic chores.

[d000hg]

The issue I'm worried about is that aluminium may not simply oxidise and stay dull, but remain powdery. Some metals do this, others like copper form a protective layer. Aluminium is quite reactive.

It's worth a try to clean it up and see what happens of course.

[WTFH]

Non-chemical answer - don't panic, but in future just wash it out with water. Get used to the fact that it will be dull (unless you use alloy wheel cleaner on it and then wheel polish).
For the inside, rinse it out, take a sponge to it and remove as much of the loose stuff as possible.

[d000hg]

So, we thoughtlessly put a Bialetti stove-top espresso pot through the dishwasher. Didn't even stop to think it mightn't be dishwasher safe. Now it has gone dull, and inside the main coffee chamber has a coating of black dust which comes off on your hand.

In hindsight I discovered Bialetti pots are anodised aluminium. I know a little about this - they are covered in a thin form of very hard, insoluble oxide formed by passing electricity through aluminium. This is not the normal way that aluminium oxidises ('rusts') and if you scratch anodises aluminium the shiny surface will oxidise with a much less hard-wearing substance.
So I believe the dishwasher has either dissolved or abraded away the entire anodised coating, and the black dust is a different form of aluminium oxide. Bummer.

The part I'm unclear of is if I remove this black layer, will it just keep happening? Is the black oxide powder the natural oxide aluminium produces, or something specific to the conditions inside the dishwasher? Online I see people recommending polish, vinegar, and heat-treating but they aren't very scientific and knowing about anodisation I'm unconvinced. Is there a way, short of re-anodising, I can get a stable coating? It doesn't have to be shiny, just something that isn't going to powder everywhere no matter how much I wash it.

Answers from people with actual science knowledge preferred