Have you ever wondered if there’s a right and a wrong way to using tin foil? Do you put the shiny side up, or down? Or does it even matter? Reynold’s, the maker of aluminum foil (that’s been around since I was a little kiddo), answered the question once and for all.

I read this answer on www.allrecipes.com (in an article written by Novella Lui, a registered dietitian nutrition and health writer).

First of all, why the two lusters—shiny and dull? Why not the same on both sides? Well, the two different shades are due to the manufacturing process. Large slabs of aluminum go through a process consisting of heat and heavy-duty rollers, where pressure is applied to compress and lengthen the aluminum.

"The final stage of the process is called cold-rolling, which includes passing two layers of foil through sets of rollers simultaneously. This further reduces the desired thickness and improves the material's final resistance and flexibility," Reynold’s pros explain. During this process, the foil comes out shiny on the side that is in contact with the polished steel rollers, and dull on the side that is not in contact with the rollers.

OK, but still, does it even matter which side of the foil we use? The short answer is no. Since the matte and gloss are a result of the foil's contact with the roller, Tiro asserts that there is no difference in the material make-up of both sides of the foil. Whether the foil is regular or heavy duty, you can choose your preferred side to line or cover your food, as neither side will impact your food upon contact.

Reynold's scientists confirmed. "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."

Although using neither side of the foil will impact the flavor and appearance of your cooked food, it is recommended using heavy-duty foil for grilling and roasting as they are thicker than regular foil and offer added strength.

However, there is an exception to that rule: While conventional aluminum foil doesn't require using a specific side for cooking, an exception applies to non-stick aluminum foil. Regular foil isn't inherently non-stick, but many companies produce a non-stick aluminum foil containing an FDA-approved coating on the dull side, This means foods should be placed on that side to get the benefits on the non-stick coating, ensuring easier, cleaner removal of cooked food.

Reynold's has a handy trick for remembering which side of its non-stick aluminum foil should be facing up: "If you can read the writing on the foil then you have the right side up."

All this said, there are times when NOT to use aluminum foil. It depends on cooking methods and certain foods. Avoid using aluminum foil to cover brining meats, for instance. While it’s an excellent barrier to light and oxygen, the aluminum can react with salt-heavy foods, forming aluminum chloride crystals on the food, which can cause food to taste bitter.

It’s also not recommended using foil to line your baking sheet when baking cookies. Doing so will create an uneven baking.

Finally, don’t use foil to cover or store your leftovers. It’s just not meant for this job, as it doesn't provide an airtight seal to protect your food.