Aluminum foil is a thin sheet made of pure aluminum that is made through a special production process. During the production process, the two sides of the aluminum foil may be treated differently to meet different needs and therefore exhibit different properties. There is a significant difference between the two sides of aluminum foil, the glossy side and the matte side. The glossy side is perpendicular to the rolling direction and the matte side is parallel to the rolling direction. So why does aluminum foil have two sides?
1.Manufacturing Process of Aluminum Foil
The process of preparing aluminum foil involves making thin sheets of pure aluminum through a rolling process.
Melting: Melting aluminum ingots into liquid aluminum.
Casting: Liquid aluminum is cast into thin sheets.
Stretching: The sheet is stretched to the desired thickness. (During the stretching process, the surface of the aluminum foil is subjected to friction, resulting in the formation of glossy and matte surfaces.)
Cooling: The stretched sheet is cooled to room temperature.
Rolling: The cooled sheet is rolled into a coil.
2.Surface treatment and coating
In the final stage of aluminum foil preparation, coatings or other treatments may be applied to change its surface properties. This is one of the main reasons why aluminum foil has two sides. One side may be coated or treated to increase its moisture resistance, improve oxidation resistance or increase the barrier effect against specific substances. The other side may remain more pristine to meet the needs of other applications.
3.Functional differences between glossy and matte surfaces
The glossy side has a smooth surface due to friction and has better reflectivity. For this reason, glossy surfaces are often used to package food products to prevent them from spoiling.
The matte side has a rough surface due to friction and has better adsorption properties. Therefore, the matte side is usually used in cooking to prevent food from sticking to the aluminum foil.
In addition, the glossy side is easy to clean due to its smooth surface. The matte side tends to accumulate dust and grease due to its rough surface.
Precautions for using aluminum foil
The following precautions should be taken when using aluminum foil:
Do not use aluminum foil to wrap foods that are highly acidic or alkaline to avoid chemical reactions with aluminum.
Do not heat aluminum foil directly on an open flame to avoid melting or deformation of the foil.
Do not reuse the aluminum foil to avoid the coating on the surface of the foil peeling off and releasing aluminum elements.
The two sides of aluminum foil have different properties, so care should be taken to distinguish them when using. Correct use of aluminum foil can prolong its service life and safeguard human health.