The surface defects and roughness of orthodontic Ni–Ti archwires are related to the manufacturing and surface finishing processes employed. On grouping archwires according to their surface characteristics instead the commercial brand, comparisons can be made of the influence of different surface finishings upon the corrosion resistance of Ni–Ti archwires. This novel approach shows that orthodontic Ni–Ti archwires can be grouped into 5 surface patterns according to a dominant surface defect. Each pattern is derived from a given manufacturing process and shows a different response to corrosion in several media.