1. Look at the color: Anodized aluminum prodsucts usually come in different colors, which can range from light white to dark black. This is due to the difference in the thickness of the alumina film and the composition of the electrolyte. Generally speaking, the thicker the aluminum oxide film is, the darker it is.
2. Check the surface texture: The surface of anodized aluminum prodsucts is usually rough, with obvious texture and holes, which are caused by the formation of aluminum oxide film.
3. Check surface hardness: Anodized aluminum is generally harder than untreated aluminum due to the fact that the aluminum oxide film is harder than the aluminum itself.
4. Chemical testing: Chemical reagents can be used to test whether aluminum prodsucts have been anodized. For example, an acidic solution can be used to detect whether the surface of an aluminum prodsuct contains an aluminum oxide film.