aluminium pans

[Jules]

There's an answer to that: pressure washer!

[The Natural Philosopher]

arguably wire wool is more palatable than aluminium anyway.

[The Natural Philosopher]

No. That's aluminium acetate or carbonate I think.

Normally al is actually protected by an ultra thin tough oxide layer that forms within minutes of it being cut.

That however is prone to acid and salt attack, and that's when you get Al corrosion.

[Bruce]

True - there's no risk of Alzheimers, and many people would benefit from higher levels of iron. ;-)

[Bruce]

I only asked a question because I thought it was more polite to the previous poster than making a bare statement. But a statement would have been appropriate, because aluminium oxide *is* white.

No question. ;-)

[Andy Dingley]

Aluminium's "natural" oxide layer from air alone is weak, and takes an hour or two to form. It's easily disrupted afterwards by even gentle mechanical scraping.

Anodising is the deliberate assisted formation of the oxide layer. In particular, the layer formed can be made far harder than the naturally forming layer. Even a cheap bare aluminium pan will have had some degree of deliberate anodisation or passivation done to it.

Passivation is a similar process to anodisation (usually chemical rather than electrolytic) which also give a thicker, stronger oxidised layer than air or water exposure. Particularly for stainless steel, robust kitchen use of either aluminium or stainless depends on passivation - if you don't passivate, either metal will be prone to staining. Many simple kitchen materials are active enough to cause some passivation "naturally" on their first use, without you even noticing, but this isn't the same as simple air exposure. In particular, stainless ought to be passivated with uncoloured citric acid before something more colourful gets to it and makes a permanent stain.

[Tim Streater]

Would this be removed by rubbing with ScotchBrite type items?

[Steve Firth]

mean nothing to you?

[Steve Firth]

The actual reason for cautioning against the use of steel wool to polish aluminium arose because if one is preparing (say) Birmabrite for repainting then it should be cleaned using only an aluminium oxide paper or grit blasting with aluminium oxide. This is because use of a wire brush or steel wool will leave traces of steel on the aluminium. In the case of a wire brush, particularly a rotary wire brush, splinters of steel may be embedded in the alloy. Steel wool is unlikely to embed steel in the surface since the steel wool is more flexible than the wires in a brush and it is not driven at speeds exceeding 650rpm. Steel wool may however leave behind steel dust.

For that reason I wouldn't use steel wool to polish alloy wheels, I wouldn't polish a Land Rover with steel wool prior to painting it.

To claim that steel wool can do any permanent or irreparable harm to an alloy pan is ludicrous. I somehow suspect that those whining about the use of steel wool for cleaning pans quite happily use metal utensils for cooking without worrying about the contact of dissimilar metals.

[Colin Trunt]

The active ingredient in OxiClean is sodium percarbonate, an adduct of sodium carbonate and hydrogen peroxide.

Having a google indicated perhaps aluminium hydroxide.

Anyway whatever it is there are two ways to go I would imagine either acid or alkali. So try vinegar as acid and baking soda as alkali. Oven cleaner, sodium hydroxide might do the trick.

If you can't get it off you could patent the idea as non-stick pans in which the black stuff does not come off :O)

[Andy Dingley]

Which grade? Workshop Scotchbrite / Webrax has grit in it that will easily go through hard anodising.

In normal use, with a cast aluminium pan (sheet alloys form harder passivation layers), a passivated layer is enough to resist "typical" scouring, but the naturally formed layer isn't. So after a really hard scouring of a pan, it's not uncommon for it "to never be clean again"

- as fast as it forms another oxide layer, everyday cleaning takes it off again. The fix is to then clean it once, and re-passivate properly (it's easy - a soak in citric acid will do).

With stainless it's mostly a problem after mechanical work on it, such as installing taps etc.

[Colin Trunt]

I think it is, but you can see pictures of white, grey and indeed brown if you look on the web. I think it is white however on a sauce pan or whatever it will look grey I think. Basically aluminium is metalic silver/grey in colour when liquid it you melt it and stir but the oxide soon forms, I guess it is white but so thin that it look grey as all aluminium does. If you get alot of the oxide on it it might look more white.

Actually I think it may be manganese oxide, which is black so it may be some sort of alloy of aluminium.

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