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As the title says, is the aluminium foil still usable in this condition?

If you notice, there's a very obvious white portion in the center of the aluminum foil and the entire roll is like that. Usually when I buy it from the store, it is pure silver without the white line. However when I keep it for some time, this white line appears which appears to me that the foil could be "spoilt"?

Aluminium foil with white stripe

May I also ask what is the name of the condition of this aluminum foil and what causes it to be like this.

Fabby
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Astralis
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1 Answers1

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That's just aluminium oxide (Al2O3) and it's harmless as:

  • it's insoluble in water
  • it's nearly insoluble in alcohol.
  • is very hard (Basically the same material as a ruby or a sapphire)
  • it's chemically nearly inert
  • Is basically the same substance as the non-shiny side of the Aluminium foil

So it's definitely useable for all intents and purposes. (including cooking ;-) )

Fabby
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    It's also just a thicker layer of what all aluminium foil has on the surface. – Chris H Oct 04 '18 at 06:31
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    not doubting you, however i can't help but to ask if there's any studies or sources to prove this? My parents are health freak but i have so much of such foils at home. If i can't convince them, they are all going to waste. – Astralis Oct 04 '18 at 19:17
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    @Astralis if you want scientific **proof:** send the foil off to a chemical lab and have it tested and provide the test results to your parents. From where I am across the Internet, that's what it *looks like* with a high certitude, but without a sample, I cannot test this in my lab... **¯\\_(ツ)_/¯** – Fabby Oct 04 '18 at 19:50