Professional paper
https://doi.org/10.17018/portal.2021.11
Stabilization of iron-gall ink using the phytate treatment
Jelena Duh
orcid.org/0000-0002-9334-2290
; National and University Library in Zagreb, Depratment for Preservation and Storage
Abstract
In Western civilization, iron-gall ink was the most commonly used writing medium from the early Middle Ages to the late 19th century. Due to the high acidity of the ink, the surface on which the ink is used rapidly degrades. In the case of paper, corrosion of iron-gall ink accelerates the process of hydrolytic decomposition of cellulose from paper fibres, while acidic hydrolysis products further stimulate oxidation reactions. As a result, the paper darkens, becomes brittle, eventually cracks, and completely disintegrates. There is no universally accepted solution for this conservation problem, which threatens a significant portion of the world’s written heritage. Most heritage institutions dealing with manuscripts written on paper with iron-gall ink focus on preventive conservation which can significantly slow down the decay process. However, targeted individual conservation and restoration interventions should be used for manuscripts that are already in an advanced stage of disintegration, since methods of preventive protection will not stop their disintegration. In the 1990s, the Netherlands Institute for Cultural Heritage proposed a method of conserving manuscripts written on paper with iron-gall ink using the phytate treatment. The process consisted of complexing unwanted Fe2+ into water-soluble Fe3+ ions by immersing the manuscript in a calcium phytate solution, and then rinsing off the water-soluble products by immersion in a solution of calcium bicarbonate, which also left an alkaline reserve in the manuscript. The procedure has been extensively researched, both on laboratory-prepared samples and on original manuscripts, and it is considered the most effective method of preserving severely damaged manuscripts. Due to its invasiveness, limitations and possibly significant side effects, this method is certainly not the first choice for conservator-restorers working on manuscripts, but it is an important part of the comprehensive protection of manuscript heritage. This paper presents, in addition to a theoretical base for the phytate treatment, the practical aspect of manuscript conservation using this method on three manuscripts that have undergone the conservation process at the Preservation and Storage Department of the National and University Library in Zagreb. Due to the specific state of preservation of each of the three selected manuscripts, the course of conservation and restoration research, the work on the manuscripts, and the decision-making process on the most adequate materials and methods of intervention, was not the same. The research and conservation carried out reaffirmed that the necessary precondition for achieving the best results is basing decisions on quality conservation research, good information about the possibilities of conservation methods, and adapting the method to each individual manuscript.
Keywords
phytate treatment; calcium bicarbonate; calcium phytate; conservation; restoration; paper; manuscript; stabilization; iron gall ink
Hrčak ID:
270799
URI
Publication date:
27.12.2021.
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