The Reason Why Aluminum Foil Is Shiny On One Side

source: The Kitchn via Lauren Volo

There are so many everyday objects out there that have hidden meanings behind them. For example, did you know that plastic pen caps have holes in the top in the event that someone accidentally swallows one, so air can still pass through their airway? Or that the holes in ladles exist as a way to measure out one serving of pasta? There’s another everyday object that has a surprising, somewhat hidden use. And that’s tinfoil.

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Have you ever wondered why one side of tinfoil is shiny, while the other side is more matte? I’ve often thought about this, and have never really been sure which side I’m supposed to be using when. Well, Reynolds Kitchens, makers of Reynolds Wrap aluminum foil, is here to answer our burning questions.

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So, what’s the difference between the shiny and matte sides? “This is a common question, and the answer is that the foil is ‘milled’ in layers during production,” explains Reynolds. “We mill two layers in contact with each other at the same time, because if we didn’t, the foil would break during the milling process. Where the foil is in contact with another layer, that’s the ‘dull’ side. The ‘shiny’ side is the side milled without being in contact with another sheet of metal.”

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So, which side should you be using? “With standard and heavy duty foil, it’s perfectly fine to place your food on either side so you can decide if you prefer to have the shiny or dull side facing out,” explains Reynolds. So there you have it! Another one of life’s greatest mysteries has been solved!