Tinplate is actually a composite material, its core part is low-carbon steel plate, and the surface is plated with a thin layer of tin. Therefore, tinplate is mainly composed of two materials: steel plate (iron) and tin.
The main component of tinplate cans is steel, on which a thin layer of tin is coated to prevent rust and corrosion. Aluminum cans are made entirely of aluminum, a lightweight metal with a density of about one-third that of steel.
The black marks in tinplate cans are usually caused by corrosion of the can. When the metal in the can reacts with the acid in the food or environment, corrosion occurs, resulting in black marks in the can.
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