There may be several issues here:

1. Primary-colored aluminum rods may not be semi-finished, because undyed alumina is colorless.

2. The coating is a coating, and the oxide layer is an oxide layer. The properties are completely different.

1. Chemical composition of anodic oxide film Gamma AL2O3. In an aqueous solution at 70 degrees Celsius, the oxide film absorbs crystal water and expands to generate 1-3 parts of crystal water oxide.

2. The oxide film is an amorphous oxide.

3. The anodic oxide film is a transparent oxide, and its refractive index N is between 1.6 and 1.65.

4. The anodized film is a non-conductive body, and its specific resistance is about 10M ohm / CM or more at 1000V.

5. The hardness of the sulfuric acid anodized film is HV230.