The Application of Aluminum Foil in Daily Life

2024.09.12

Unroll a roll of aluminum foil and you'll find that it has one shiny side and one matte side. This is not intentional, but a natural result of the manufacturing process.

The raw material of aluminum foil for food is aluminum. Aluminum is a silvery-white metal that is very light and has good ductility and conductivity. When aluminum foil is produced, it undergoes a series of processing processes to eventually form the thin and light appearance we see.

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In the process of making aluminum foil, aluminum blocks are heated and pressed into thin sheets. During this process, one side of the aluminum foil is specially polished to make its surface very smooth. Just like the mirrors in our homes, the smooth surface can reflect light very well, so what we see is the reflective side.

The other side of the aluminum foil is not polished during the production process, so the surface is relatively rough. When light shines on the rough surface, it will be scattered and will not form a strong reflection. This is why we see the matte side.

So, what are the functions of the reflective and matte sides of aluminum foil?

Generally speaking, it doesn't matter which side of the aluminum foil is used. But if one side of the aluminum foil has a special coating, such as an anti-stick layer (usually on the rough side), then the anti-stick layer should naturally face the food to prevent the aluminum foil from sticking to the food.

The reflective side can reflect light very well, so it is very useful in some occasions where light reflection is needed. For example, when we are outdoors, we can use the reflective side of the aluminum foil to reflect sunlight and make a simple solar cooker. At the same time, the reflective surface can also be used to make traffic signs, etc., to ensure that we can be seen in the dark.

The glossy side and the rough side of the aluminum foil have different reflective abilities to light, and the glossy side is obviously stronger, which means that their effects on thermal radiation are also different. But for home ovens, it doesn't make much difference which side faces outward, because the oven mainly relies on the heat convection of the air and the heat conduction of the grill to heat, so no matter which side you use, it won't heat up quickly.

Microwave ovens achieve efficient heating through electromagnetic radiation. If you put aluminum foil in, the microwaves will be reflected everywhere by it, and even sparks will be generated. Therefore, metal products such as aluminum foil cannot be put into microwave ovens.