Why Aluminum Foil Has 2 Sides And How It Impacts Cooking

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From baking up the perfect lasagna to cleaning cast iron pans, aluminum foil is a heat-resistant, convenient, and extremely versatile kitchen powerhouse. However, the handy pantry staple also inspires some mildly existential questions. Like, for example, why does it have a shiny and dull side, and does it matter?

Don't worry, this isn't like dicing onions, which you've been doing wrong all along. In most cases, the two sides of the foil function exactly the same and don't have any impact on cooking. This is a relief, but it also begs the question: if it doesn't make a difference, why does aluminum foil have two sides?

Aluminum foil has a shiny and dull side because of how it's produced. To make the classic roll of aluminum foil you might use for mess-free veggie grilling (or funny sculpture-making, we won't judge), two sheets of the super-thin metal are pressed together in a process called milling. The side of the foil that is in contact with the roller ends up glossy, and the other side turns out matte.

Generally speaking, the two sides of aluminum foil are a surface-level aesthetic issue, and don't make any difference when it comes to cooking. In other words, you can put your food on whichever side of the foil you fancy. However, there is one potential exception: if you're using nonstick aluminum foil, the dull side typically has the nonstick coating. If you accidentally put your food on the shiny side, it's no big deal, but you won't get the nonstick benefits.

To wrap things up: It doesn't usually matter which side of the aluminum foil you use, unless it's nonstick foil, in which case the dull side should be in contact with the food. Speaking of nonstick foil, the metallic kitchen staple's oven-safe nature makes it great for lining sheet pans for breezy cleanup, but unlike parchment paper, it's not normally nonstick (unless it's labeled as such). With that in mind, if you're using run-of-the-mill aluminum foil to line a sheet pan, you'll want to make sure to coat the foil with cooking spray. If you're looking for other ways to safely employ foil like an expert, check out these all-too-common aluminum foil mistakes to avoid.