Flashings should not be next to a dissimilar metal. For instance, if you put copper roofing next to an aluminum fascia with no protection, you'll get corrosion because of the galvanic action between the two materials, and premature failure will result. In addition, steel anchors must be primed to eliminate possible corrosion. The Pretreatment chemicals for both the anodizing and painting process are so harsh they can destroy non-aluminum parts. Distinguish what situations are appropriate for anodizing or painting.
Some powder coatings are hard enough for entrances, but anodizing is always safe.
Determine that the metal assembly to be finished has adequate drainage holes to prevent entrapment of the chemical solutions used for pretreatment. If they leak out later, the chemicals can damage the metal's finish. Inks and dyes in packaging materials are another potential cause of staining. Don't send door hardware or accessories to a finisher. To paint or anodize doors, the finisher must strip the hardware from the doors-most likely at an additional charge.