a method of anodizing a coil comprised of wire having a copper core and a layer of a metal formed on the core is disclosed . the metal has electrically insulating characteristics when anodized . two variations of the method are provided . in the first variation the metal - clad wire is partially anodized prior to being wound on a spool to form a coil . once the partially anodized wire is wound onto a spool the coiled wire is anodized to complete anodization . the anodized coiled wire may be rinsed to remove residual electrolytic material . in the second variation the metal - clad wire is wound on a spool to form a coil . the coiled wire is then anodized . the method of the disclosed invention reduces or entirely eliminates the presence of micro cracks in the oxide layer . the resulting coil may be used in motors , electromagnets , generators , alternators and subsystems for the same .