US Patent 7093340 Stick resistant ceramic coating for cookware

A method of making a stick resistant cook surface or cooking vessel having the stick resistance in which a hard substrate metal is treated by mechanical buffing/polishing and/or by electropolishing to a high luster surface finish of less than 20 microinches and then coated with a layer of a ceramic nitride, such as zirconium nitride. The electropolishing step is particularly suited for treating non-round shapes or deep drawn cooking vessels having high side walls, such as pots and pans, or square or rectangular shapes which are otherwise difficult to mechanically buff in the interior due to the side wall geometry and/or corners.