[China Aluminum Network] The quality of oxide film can be detected by the following methods: 1. View colors. The surface of pure aluminum that has been formed into an oxide film is milky white, cast aluminum, and mixed aluminum are grayish black. The surface without oxide film is transparent and bright white, and some also have pink or gray-black hanging cream. 2. Measuring resistance. Oxidation film has been detected with resistance and is not conductive at normal pressure. Non-oxide film can conduct electricity when detected. 3. Scratches, the surface of the oxide film that has formed is very hard, slipping when scratched with a needle, no scratches, the surface without oxide film is very soft, there are resistance and scratches when scratching with a needle. 4. Hearing sounds a crisp sound when the oxide film has been formed, and a muffled sound when the oxide film is not generated. 5. Coloring test. Oxide films can be quickly colored in the dyeing solution, and no oxide film is dyed in the dye solution.