Which side of the aluminum foil should you use for cooking: the shiny side or the matte side?

Glossy or matte? The answer is simpler than you might think — and could well put an end to an old debate in the kitchen.

Admit it: you've hesitated in front of your roll of aluminum foil. Shiny side up? Matte side down? We've all heard a different theory, often passed down like a grandmother's secret. Yet, the answer is much simpler than you think… and it might surprise you.

Glossy or matte: is there a real difference?

Look at your aluminum foil: one side is smooth and shiny, the other slightly more matte. Instinctively, we think that one must cook better than the other.

In reality? Not at all.

For conventional oven cooking, both sides function in exactly the same way. They conduct heat identically and do not influence either the temperature or the cooking of the food.

So you can use whichever side you prefer, without fear of ruining your gratin or your fish en papillote.
 

Why are there two different sides then?

The difference does not come from special treatment, but from the manufacturing process.

During lamination, two layers of aluminum are pressed simultaneously between rollers to obtain a very thin and strong sheet. The side in contact with the rollers becomes shiny, while the other, in contact with the second sheet, remains more matte.

This is simply a mechanical effect, not a special feature.

In other words: no mystery, just industrial technique.

The only exception is non-stick aluminum.

However, there is one exception.

Some rolls are labeled “non-stick”. In this case, one side has a treatment designed to limit food sticking.

And it's usually the matte side.

Manufacturers indicate this on the packaging. If your roll is marked “non-stick”, check the instructions and place the treated side in contact with the food to benefit from the non-stick effect.

Otherwise, you can continue to package your vegetables, meats or desserts without asking any questions.

Should one side be favored for better cooking?

Some misconceptions suggest that the shiny side reflects more heat. In practice, in a domestic oven, the difference is minimal and imperceptible.

Heat circulates mainly by convection (hot air) and conduction (direct contact with the dish or food), much more than by reflection.

So whether you are preparing a salmon papillote, roasted vegetables or covering a dish to prevent it from browning too quickly, the result will be the same with  cooking foil  used in either direction.

A quick practical reminder

Even if the side doesn't matter much, a few simple rules allow you to use  aluminum foil  safely:

Avoid prolonged direct contact with highly acidic foods (lemon, tomato) at high temperatures, as the acidity can slightly alter the metal.

Never use it in the microwave: this causes sparks and can damage the device.

Do not place it in direct contact with the heating elements or the walls of the oven to avoid any risk of overheating.

Following these precautions ensures safe use and optimal cooking.

The next time you unroll your aluminum foil, you can do so with peace of mind: shiny or matte, the choice is yours.