in this case the pads 26 28 are formed of a hydrophilic material such as expanded polyethylene this material directly contacts the moist tissue such as the vessel 20 and withdraws moisture from the tissue leaving a dryer surface and a resulting higher coefficient of friction between the tissue or vessel 20 and the pads 26 28 with a higher coefficient of friction slippage of the clip 10 on the vessel 20 is substantially inhibited without an increase in the occlusive force applied by the jaws 16 18 these hydrophilic properties can also be achieved by coating the pads 26 28 with a hydrophilic material although the foregoing embodiments providing increased traction have been disclosed primarily with respect to clips and clamps it will be apparent that many other embodiments of the invention can be equally advantageous as in the case of a retractor 57 illustrated in fig1 and a spreader 59 illustrated in fig1 as was the case with the occlusion instruments such as the clip 10 the retractor 57 of fig1 includes opposing jaws 16 a and 16 b with jaw surfaces 22 a and 24 a which face each other these surfaces 22 a 24 a can be provided with pads 26 a 28 a or otherwise coated or structured in accordance with any of the foregoing embodiments referring now to fig1 it will be noted that the spreader 59 also includes opposing.