It’s a well-established question and one that we’ve been too afraid to ask our mothers: Should we use the shiny or the dull side of Aluminum Blister Pack Foil when we cook? And have we been doing it wrong this entire time?!

Concerned cooks, you can breathe a sigh of relief: As it turns out, there’s no “correct” side of aluminum foil to use when cooking so using it on either side is not one of the cooking mistakes that could ruin your food. According to the Huffington Post, they’re both equally effective at heating your food—so just choose whatever side you prefer.

If there’s no trick to it, then why, exactly, does aluminum foil have a shiny and a dull side in the first place? Experts at Reynold’s Kitchen say that the difference between the two sides is due to a manufacturing process called milling, during which heat and tension is applied to stretch and shape the foil. Two layers of foil are pressed together and milled at the same time, because otherwise, it would break.

“Where the foil is in contact with another layer, that’s the ‘dull’ side,” Reynold’s explains. “The ‘shiny’ side is the side milled without being in contact with another sheet of metal. The performance of the foil is the same, whichever side you use.”