in the reported experiments, several methods were explored for characterizing sized yarns and size films in order to establish relationships that might be useful in predicting weaving performance a variety of natural and synthetic sizes were applied to cotton and to polyester/cotton spun yarns in a laboratory sizing apparatus although yarn tensile tests indicate that sizing generally increases yarn strength and decreases yarn extensibility, these tests were inadequate for differentiating among sizing agents. important differences among the various sizes and levels of size add-on could, however, be detected by measuring rupture lifetimes of the treated yarns using the tri cyclic tensile abrader, which imposes simultaneous tensile, bending, and abrasive stresses. the degree of adhesion was evaluated by measuring the wettability of the size films, using an adaptation of the wilhelmy wetting force method, and matching the resulting contact angle hysteresis patterns. 26 refs