J.CAC VOLUME 39 (2014)
The Treatment of Archaeological Papers Affected by Iron Corrosion Using Calcium Phytate
The calcium phytate/calcium bicarbonate treatment method developed for delaying iron gall ink corrosion on paper was applied to the paper components of two archaeological artifacts: a soup tin label that was unearthed from the site of a storehouse built on Dealy Island by British sailors searching for the lost Franklin Expedition, and a pocket watch that was retrieved from the waters of the St. Lawrence River after the wreck of the RMS Empress of Ireland. The soup tin label showed highly three-dimensional rust accretions and staining with both stained and unstained areas of the paper testing positive for free iron(II) and iron(III) ions. The pocket watch label showed significant yellow-orange coloured staining throughout the remains of the primary paper support and also tested positive for both iron(II) and iron(III) ions. Although neither artifact was inscribed with iron gall ink, the calcium phytate/calcium bicarbonate treatment was applied to each of them to combat the degradation of paper that results from iron(II)-catalysed oxidation and acid-catalysed hydrolysis of cellulose, while at the same time maintaining the visual cues to the archaeological context of the two objects. The treatment decision-making process and treatment steps are discussed.
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