Iron discs have been oxidised at 890 ℃ on one side only, with the other side protected by an inert gas. The scale-metal adhesion was very good. Initially, scale-metal adhesion was maintained by the scale relaxing towards the metal but after a time which depended upon the initial metal thickness, oxide relaxation ceased and the inert face moved towards the scale-metal interface. When the face which was normally inert was covered with a non-growing oxide layer, the scale-metal adhesion deteriorated. The results show that vacancies which were produced by oxidation were annihilated within the metal, that the inert face played a part and that the scale-metal interface is not a good sink for vacancies.