First, dye is not stained.

1, anodic oxidation film thickness is insufficient. The solution is to check whether the anodic oxidation process is standardized, to see whether the temperature, voltage, conductivity and other factors are stable. If there are abnormalities, please adjust the specifications accordingly. If there are no abnormalities, the oxidation time can be prolonged appropriately to ensure that the film thickness reaches the standard.

2. The pH value of dye solution is too high. At this time, the pH value can be adjusted to the standard value by glacial acetic acid.

3. After oxidation, the workpiece is placed in the sink for too long. Timely dyeing is advocated. If this happens, the workpiece can be dyed in an anodic oxidation tank or a nitric acid neutralization tank after proper activation.

4, the choice of dyes is inappropriate. Suitable dyes should be selected.

5, dyestuff has been decomposed or mildew, and dyes need to be replaced at this time.

6. Low oxidation temperature leads to dense membrane. The oxidation temperature can be increased appropriately.

7, poor conductivity. There may be poor conductivity of anode copper rod or cathode lead plate. Pay attention to cleaning anode copper rod and cathode lead plate to ensure good contact.