γ-γ coincidence methods have been applied to obtain absolute flank and crater wear volumes from irradiated high speed steel (HSS) tools using 60Co as the radiotracer. Consistent absolute results can be obtained irrespective of the exact counting geometry offered by a given chip sample. Flank wear volumes obtained by the γ-γ counting method have been compared in a series of orthogonal cutting tests with results deduced from microscope measurements on the clearance face of the radioactive tools. © 1977.