Measuring effectiveness of washing methods for corrosion control of archaeological iron: problems and challenges

The individual chloride content of 116 archaeological iron nails from Romano British and Medieval sites in Wales is reported. The meaning and value of chloride concentration recorded as weight of chloride in object/object weight is discussed in relation to reporting the effectiveness of washing methods designed to remove chloride from archaeological iron. This is theoretically compared to the concentration value weight of chloride in object/metal surface area of object and the difficulty of quantitatively determining the success of washing methods as stability enhancers is discussed. It is concluded that assessing the impact of residual chloride on post-treatment corrosion of archaeological objects has the potential to offer the most significant guide to treatment success. Keywords: Iron, Archaeology, Corrosion, Chloride, Treatment, Washing, Assessmen