There are many ways to remove the oxide from nitinol, including acid etching, mechanical polishing, grinding, and electropolishing. Acid etching leaves the surface rough and mottled, which is good for adhering coatings. Mechanical polishing, which is specific to wire, leaves the surface with a bright, smooth,  sanded appearance. This type of polishing is good when the wire needs to look similar to stainless steel. Centerless grinding is capable of holding very tight tolerances on discrete lengths of wire or tube. Electropolishing is typically used when nitinol will be implanted and is done as the last step in the process. This process creates a mirror-smooth surface and creates a biostable oxide. Some suppliers of nitinol have developed proprietary processes to remove the oxides that do not require the use of harsh acids but yield similar results.