Aluminium oxide coloring color surface flower

Flowers are mostly found in large-area aluminium products for several reasons:
①The pretreatment of the product is not clean by alkali cleaning, and the original oxide film on the surface of the substrate is not removed cleanly.
②The pre-treatment of the product has not carried out light emitting treatment, or has not carried out oxidation for a long time
③ dyeing temperature, low concentration.
④ There is oil stain on the surface of the dyeing tank. Shake a few times while dyeing
⑤ The oxide film of the reworked product is not removed cleanly
⑥ The oxide film is polluted. Before dyeing, the product should be kept clean and should not come into contact with other things.
⑦ Oxidation time, temperature and concentration are out of the normal process.