Drawing and surface oxidation is independent of the drawing to do before oxidation; oxidation method is also certainly not with natural oxidation, surface natural oxide obtained should be called the quality defects, the oxide film and oxide film composition, the appearance of special treatment are different.
Another point is that coloring is not oxidation post-treatment. It is carried out at the same time of oxidation. There are usually several following coloring methods: coloring anodic oxide film, anodic oxide film of aluminum, dyed by dyes.
The anodic oxidation film of spontaneous color is a specific aluminum material, which is formed on the basis of some suitable electrolyte (usually organic acid), and produces an anodic oxide film spontaneously from the alloy itself under the action of electrolysis.
The coloring of an anodic oxide film that is coloured by electrodeposition of metal or metal oxide through the void of an oxide film.