54 Resistance to corrosion test54.1 After being tested as described in this section, ferrous parts, including enclosures, of three devicesshall not show evidence of corrosion.54.2 All grease is to be removed from the parts to be tested, by immersion in either ethyl acetate, acetone, or methylethyl ketone for 10 minutes. The parts are then to be immersed for 10 minutes in a 10 percent solution of ammonium chloride in water at a temperature of 20 ±5°C (68 ±9°F).54.3 Without drying, but after shaking off any excess drops by hand, the parts are then to be placed for 10 minutes in a chamber containing moisture-saturated air at a temperature of 20 ±5 °C (68 ±9°F).54.4 The parts are then to be dried for 10 minutes in a heating cabinet at a temperature of 100 ±5°C (212±9°F), and their surfaces shall not show any signs of rust.54.5 Traces of rust on sharp edges and yellowish film removable by rubbing are to be ignored.54.6 Small helical springs and the like, and inaccessible parts exposed to abrasion, are to be considered protected against corrosion by a coating of grease. Such parts are to be tested only when the effectiveness of the grease film is in doubt, and the test is then made without previous removal of the grease.