We have measured the concentration dependence of the transmission conduction electron spin resonance linewidth of copper doped with Li, Zn, Ga, Ge, As, Ni, and Ti. In each case, we find a linear concentration dependence which allows us to determine a spin-flip cross-section, σsf, for each impurity. These cross-sections, together with those deduced from linewidth data previously published for other impurities (both magnetic and not), form a useful body of results and allow one to test spin-flip scattering models. We find an overall agreement of our values for σsf for transition metal impurities with estimates based on the Friedel virtual bound state model, including a spin-orbit interaction. For specific impurities (Zn, Ga, Ge, and As) we find that σ sf is determined by the charge contrast between the impurity and the copper host as was noted earlier from similar studies based on Li and Na by Asik, Ball, and Slichter. A particular situation is present with Li as an impurity in copper, interpreted as a « spin-orbit hole », which, together with the other results, confirm that the spin-orbit difference between the impurity and the host is the relevant spin-orbit parameter for σsf