[en] A previously formulated model for nuclear abrasion in ion-ion collisions where nucleons in both projectile and target can be excited is expanded. Describing the state of excitation by an effective channel unitarity is rigorously imposed and the results are compared with those of a heuristic treatment of unitarity by Hufner, Schafer and Schurmann. Corrections to the latter theory which grow up to a factor 2 with the number of abraded nucleons are found. (author)