GB wrote
The Natural Philosopher wrote
GB wrote

We have a very old Kenwood mixer, with aluminium beaters. We
unfortunately put them in the dishwasher, and they are now covered in a
soft black deposit. What's the best way to get that off and if possible
restore the finish?

AlO2?
possibly strong caustic, better an acid of some sort...
vinegar/lemon juice rhubarb or maybe a de-scaler?

I tried vinegar, but that had no effect.

The black stuff does come off with a scourer, but now that the original
shiny finish has gone, it discolours very easily.

Yeah, once the anodising is gone the only viable approach is to get
replacements.

Should be replacements on ebay given that
the mixer itself will have died for some.