Iron Gall Ink Corrosion on Parchment. Preliminary Evaluation of Treatment Methods Using Aqueous Solutions

Abstract Ink corrosion on parchment is a phenomenon that, unlike its counterpart on paper, has so far been little researched. The same applies to the options for conservation treatment. In order to provide a guide for conservation practice as well as further research, five water-based treatment methods were examined: calcium phytate with pH 5.3 or 3.0, a 0.5% (w/w) solution type B gelatine, a 1% (w/w) solution of phytic acid at pH 2.2 and calcium phytate in combination with gelatine. These were tested on 70 specimens cut from on piece of buffed vellum and 36 specimens from an early modern deed on parchment that showed signs of ink degradation. After treatment and accelerated ageing, the samples were examined with colorimetry and ATR-FTIR spectroscopy and tested with bathophenanthroline for free iron ions. None of the tested treatment methods achieved a fully reliable inhibition of ink corrosion, but apart from a moisture-catalysed acceleration of degradation reactions, no adverse effects were observed either. Results from ATR-FTIR suggest that oxidation plays a more important role in damage related to ink corrosion of parchment than hydrolysis.