corrosion of surgical instruments [L, corrodere, to gnaw away] , the rusting of surgical instruments or the gradual wearing away of their polished surfaces caused by oxidation and the action of contaminants. Though minimized by the use of stainless steel alloys in the fabrication of the instruments, corrosion persists as a problem, even when cleaning procedures seem more than adequate. It usually results from inadequate cleaning and drying of surgical instruments after use, sterilization with solutions that eat into the surface, overexposure to such solutions, or a faulty autoclave. Cleanliness is the single most important factor in preventing corrosion. Any foreign material, either organic or inorganic, on the surface of stainless steel is likely to promote corrosion, and microscopic examinations often reveal foreign material and chlorides from cleaning solutions scattered over the surface of cleaned and sterilized instruments. The more chromium in the stainless steel alloys of which surgical instruments are made, the more resistant the instruments are to corrosion. Carbon, which hardens such alloys, also reduces their resistance to corrosion. Most corrosion of surgical instruments is superficial and may be removed by soaking in a solution of ammonia and alcohol or by repolishing by the manufacturer.