1. The thickness of the film is uneven. The possible reason is that the temperature and concentration of the anodic oxidation tank are not uniform. Compressed air stirring should be carried out to solve these problems.

2, the temperature or concentration of dye solution is uneven. The mixing process is introduced.

3, dyeing speed is too fast. The bottom of the workpiece enters the dye solution first, leaving the dye solution at last, so the bottom is most easily stained. The solution is to dilute the dye and extend the dyeing time appropriately.

4, poor conductivity. It may be caused by loosening of the hangers. Attention should be paid to tighten up to avoid such problems.

5, dye is too thin, can add dye, increase the concentration.

6, dye solution temperature is too low. The dye can be heated to below 60 degrees Celsius.

7, dyestuff dissolves improper or has insoluble dye floats, this is easy to produce chromatic aberration. The solution is to improve dyestuff dissolution.