J.CAC VOLUME 25 (2000)
Evaluation of Storage Solutions for Archaeological Iron
This study, carried out between 1983 and 1985, focusses on the evaluation of six solutions for their effectiveness as storage solutions for archaeological iron. These are aqueous solutions of sodium carbonate (1%), sodium hydroxide (1%), alkaline sulfite (0.5 M sodium hydroxide and 0.5 M sodium sulfite), and ethylenediamine (2%), seawater (synthetic) and deionized water. Groups of about 30 wrought iron nails from either a land or a marine site plus a pure iron coupon were stored for one year at room temperature in each of the six solutions; the dissolved oxygen and chloride ion concentrations in the solutions were monitored regularly. After one year in the storage solutions, 75% of the nails were treated (by ethylenediamine (5%, 60°C), alkaline sulfite (60°C), or hot washing) and the remaining 25% were assessed for susceptibility to corrosion by exposing their cross-section to open air at about 50% relative humidity. Alkaline sulfite and sodium hydroxide solutions were the most effective solutions for storing archaeological iron and are recommended. The sodium carbonate solution was less effective. The ethylenediamine solution, synthetic seawater and deionized water are not recommended because of the probability of iron corrosion during storage.
Download: JCAC25 Costain