Cleaning Blackened Aluminium

[woofgang]

A few months ago someone posted about aluminium cooking utensils getting coated in a black greasy powder after being in the dishwasher. I found a website with a solution and posted it but didn't save the website and now can't find the question in my answered questions. Does anyone remember it please?

[carrust]

I was told never to put aluminium in the dishwasher as the detergent has an abrasive in it & pit marks the metal surface.

[EDDIE51]

Aluminium that is used for cooking utensils has a small % of Copper added to harden it, pure Aluminium is too soft.
The Black is Copper that has been exposed by the etching of the Aluminium by the alkaline dish wash detergent. Copper need an acidic cleaner like lime scale cleaner to remove it. You could try soaking it in cola which contains Phosphoric acid, if that does not work try some lime scale remover. You need to leave it on for an hour or two and probably repeat it. It will not harm the Aluminium which is unaffected by most acid but attacked by alkali .

[woofgang]

lime scale remover! that was it!! many thanks

[EDDIE51]

This link recommends vinegar( which is an acid) and if still black then baking soda
http://www.ehow.com/how_12104796_clean-blackened-aluminum.html
and carrust is correct never put Aluminium in a dishwasher or it will etch it!

[carrust]

It etched my cheap wine glasses, eddie:-(

[EDDIE51]

^^ Yes Cheap glass ( called Soda glass) and Crystal will be etched , the only glass that is fully dishwasher proof is 'Pyrex' or similar. ( Borosilicate Glass)

[woofgang]

Update for anyone who has the same problem. 12 hours soak in a 50 50 mix of thick limescale remover (the toilet kind) diluted with hot water and then left to cool loosened the deposit enough that a stainless steel scrubber and washing up liquid removed it. It was the gas burners from my cooker, they now look reasonable again.

[Mamyalynne]

Here's the question you were searching for, glad you got sorted.


http://www.theanswerbank.co.uk/Science/Question1342928.html

[woofgang]

thank you mamya!

[Mamyalynne]

:-)