For stainless steel: background, passivation, pickling, degreasing, electropolishing, grinding, mechanical cleaning, sand blasting, blackening, barrel finishing
For carbon steel: galvanization, painting, black oxide, hot dip galvanizing, shot blasting, carburizing, nitriding, high-frequency quenching
For copper/brass: polishing
For aluminum: anodizing, painting, powder coating, chrome plating, nickel plating, etching, electrophoresis, wiredrawing, sand blasting, polishing,
For magnesium:  anodizing, electroplating, electrophoresis, PVD, passivation, painting
For zinc: chrome plating, electro polishing, nickel plating.