2 The colorless oxide film anodized by sulfuric acid does not allow: other mottled colors, or surface blooming, blackening, dark lines, etc. due to poor surface preparation, or defects caused by poor sealing. The oxidized anodized film of sulfuric acid should be orange-yellow after being blocked by potassium dichromate. It is not allowed to have a white and light color due to poor sealing. The colored oxide film should be brightly colored and meet the requirements of the dyeing sample. Do not allow: bright spots, dark spots, uneven color.
3 Oxalic acid anodized film has different thickness depending on the type of current used, and the surface is yellow-green to dark brown.
4 The chromic acid anodized film generally consists of gray to grayish black, and is not allowed to have: yellow spots, white spots, redness and blackening of the local film layer.