A simple washing procedure has been developed for stabilization of corroding aluminum-copper alloys. The use of an ammonia-ammonium sulphate buffer at pH 9.6 in aerated deionized water effectively removes cemented copper metal and copper corrosion products from the surface of the object while also removing aggressive chloride ions. This treatment has been used to stabilize a Duralumin sea-plane float which was actively corroding after 46 years' exposure to a marine environment.