Towards quantified assessment of aqueous chloride extraction methods for archaeological iron: De-oxygenated treatment environments

The advantages and disadvantages of treating objects by aqueous washing methods are discussed. Chloride bearing corrosion products on iron are related to aqueous chloride extraction treatments. Alkaline sulphite; de‐aerated sodium hydroxide; de‐aerated Soxhlet; de‐aerated water; sodium sulphite and aerated water washing methods are applied to archaeological iron, measured and quantitatively compared. De‐aerated alkali was the best and most predictable chloride extractor. This is attributed to prevention of corrosion during treatment and the action of hydroxyl as a counter ion