1, wash water is not clean, should strengthen the water wash.

2, the water used for washing is too dirty and easy to pollute the film. At this time, water should be replaced to ensure the quality of washing.

3, oxide film is polluted by smoke, acid and alkali fog in the air. Strengthening water washing, timely dyeing and timely transfer can greatly reduce this symptom.

4, oxide film is contaminated by oil and sweat. Protection must be strengthened and hands can not be used to touch the appearance of the workpiece.

5. There are insoluble impurities in the dye solution, which are contaminated by oil and destroy normal dyeing. At this time, the dye solution should be filtered or replaced.

6, the workpiece gap, deep hole in the residual acid outflow, for this kind of workpiece to strengthen water washing.

7. When the dye solution is contaminated by Cl-and pitting corrosion occurs on the dyeing workpiece, dyes must be replaced at this time, and attention should be paid to avoiding the introduction of impurity ions in the operation process.