We are sure that we have all had the question cross our mind at some time in our lives—why does aluminum foil have a dull side and a shiny side—and which side should we use?
The answer is—it doesn’t matter what side you choose to use, as there is no definitive “correct” side. According to experts, either the shiny or the dull side is equally effective for heating your food.
So, now the question is if one side is as practical as the other, why does it have a dull side and a shiny side, to begin with? According to the people over at Reynold’s wrap, a long-time producer and seller of aluminum foil, the difference in appearance between the two sides is due to a process in the foils manufacturing referred to as milling.
Milling is a process by which both heat and tension are applied to the foil to stretch and then shape it. Two individual layers of foil are pressed together and then milled at the same time. If the process is not performed in this manner, the foil will break.
Reynold’s explains that:
“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. The overall performance of the foil is the same no matter what side you choose to use.”
Now, if you are using non-stick foil, there is a difference, and you will need to pay close attention to the side you use. With this type of foil, the non-stick coating is only applied to one side of the foil, being the dull side and the side you will want to use.
Don’t worry if you don’t remember which is which, as the non-stick foil will generally have its “non-stick side” labeled just in case you forget.