1. The oxide film layer must have sufficient porosity
2. The inner wall of the membrane pore maintains a certain activity
3. The anodic oxide film of aluminum in sulfuric acid solution is colorless and porous, so it is most suitable for dyeing.
4. The oxide film must have a certain thickness, and the thinner film can only be dyed with a very light color
5. The hard anodic oxide film uses chromic acid conventional oxide film, which is not suitable for organic dyeing
6. The oxide film layer should be complete and uniform, and there should be no defects such as scratches, blisters, and pitting corrosion.
7. The film itself has a suitable color, and there is no difference in metallographic structure, such as different grain sizes or severe segregation. Therefore, there are certain requirements for aluminum alloy materials. The alloy composition includes silicon, magnesium, manganese, iron, copper, When the content of chromium is too high, it will often cause the oxide film to be dull, and the color tone changes during dyeing.