What is the purpose of the oxide film on the surface of an aluminum pot? How to protect it?

That dark, even slightly yellowish oxide film is the "guardian" of the aluminum pot.

The function of the oxide film: This naturally or artificially formed aluminum oxide film (anodized films are thicker and more uniform, and are light yellow) is dense and stable. It tightly covers the surface of the pot, separating food from the aluminum substrate and preventing aluminum from dissolving into the food during cooking. It also enhances the pot's corrosion resistance. In short, protecting this film is equivalent to protecting the pot's safety and lifespan.

How to protect it:

Avoid physical damage: Use a soft sponge or scouring pad for cleaning, along with dish soap or scouring powder. Never use steel wool, sand, or wood ash to abrade it, as this will directly scrape off the oxide film.

Avoid chemical corrosion: Avoid storing leftovers (especially spicy, sour, and salty dishes) in the aluminum pot for extended periods, and avoid exposure to strong acids and alkalis.

Recommendation for first use: When using a new aluminum pot for the first time, it is best to use it to cook porridge rather than boil water or steam buns. This will help to form a denser oxide film on the surface.