Aluminum foil is often used, not only to keep food hot, baking or grilling but also for the transportation of food. You would have noticed that the aluminum foil has two different sides, one is glossy, and the other is matte finished. But why does aluminum foil have two different sides? Let’s find out.

Aluminum foil can be found in almost every household and can be used for cooking and baking, grilling, and above all, keeping food hot or fresh. The film has a matt and a glossy side. Both have special physical properties. However, to most of us aluminum foil users, it does not matter which side lies inside or outside when wrapping food.

Physical properties of matt and glossy surfaces

Glossy surfaces reflect light and heat more than matt ones. If you want to keep food warm with aluminum foil, you would need to turn the shiny side inside. The heat in the film could be reflected back on the product wrapped in it. On the other hand, if dishes are to remain cold, the shiny side is often turned outside. So less heat penetrates from the outside to the inside. In addition, the matt surface inside the foil should absorb the heat.

two different sides of aluminum foil
Image Source – Needpix

However, these effects only play a role at very high temperatures, for example at 500 degrees. Below that, they have little effect. From a functional point of view, both sides of the aluminum foil are actually equivalent.

Why aluminum foil has two different sides

Accordingly, aluminum foil does not have two different properties because of the different properties of matt and glossy surfaces. Rather, the reason for this lies in the method of manufacture. In order to produce the very thin foils, which is typically thinner than 0.2 millimeters, two superimposed webs are rolled together in the final rolling step. This is known as double rolling.

In this process, the respective outer sides of the two foils come into contact with the polished surface of the work rolls. They are smoothed and appear shiny. The inside of the foils, on the other hand, roughen up somewhat as a result of contact with one another and therefore look matte.

Too much aluminum is dangerous for the body

Why do aluminum foil has two different sides
Image Source – Needpix

Too much aluminum in the body can damage the nervous system since aluminum is already contained in many food and cosmetic products, consumers should avoid additional exposure to the substance. Aluminum foil should, therefore, be used with caution.

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