Six derusting methods were tested on a large number of drills from a sunken ship recovered from a drained area in Northeast Holland. Methods included: citric acid, sulfuric acid, orthophosphoric acid, thioglycolic acid, sodium hydroxide and sodium gluconate, and rainwater. Treatment was by immersion with daily removal, inspection, and brushing until completely derusted. The last two methods yielded best results. 3 surface treatments were tried for subsequent preservation.