Answer:

anodize

Answer	Crossword Clue
ANODIZE	Put on a protective coat, as with metal
ANODIZE	Enhance by coating, as metal
ANODIZE	Subject to electrolytic action

ANODIZE	Coat metal
ANODIZE	Coat electrolytically
ANODIZE	Coat by electrolytic action
ANODIZE	One way to coat a metal