Jana Kolar 1,2 , Alenka Možir 2 , Matija Strlič 3 , Gerrit de Bruin 4 , Boris Pihlar 2 , Ted Steemers 4 published by STABILISATION OF IRON GALL INK: AQUEOUS TREATMENT WITH MAGNESIUM PHYTATE 19 FULL PAPER 1. Morana RTD d.o.o., Oslica 1b, 1295, Ivančna Gorica, Slovenia 2. University of Ljubljana, Faculty of Chemistry and Chemical Technology, Ljubljana, Aškerčeva 5, 1000 Ljubljana, Slovenia 3. University College London, Centre for Sustainable Heritage, The Bartlett School of Graduate Studies, Gower Street (Torrington Place site), London WC1E 6BT, UK 4. Nationaal Archief, The Hague, Prins Willem Alexanderhof 20, 2509 LM The Hague, The Netherlands corresponding author: jana.kolar@morana-rtd.com received: 14.12.2007 accepted: 31.12.2007 key words: Paper degradation, oxidation, conserva- tion, antioxidant, iron gall ink, aqueous treatment e-PS, 2007, 4, 19-24 ISSN: 1581-9280 web edition ISSN: 1854-3928 print edition www.Morana-rtd.com © by M O R A N A RTD d.o.o. Corrosive iron ions and acids in iron gall inks lead to enhanced degradation of paper. Several conservation prac- tices have been used to stabilise endangered documents in the past centuries. The most effective aqueous stabilisa- tion method developed to date is the so called “Calcium phytate” method. In this contribution we demonstrate that a treatment using magnesium phytate is equally effective, while additionally exhibiting several advantages. Due to the higher solubility of magnesium phytate compared to calci- um phytate, it is not required to add an aqueous solution of ammonia, which poses several health risks. It is also shown that in order to optimise the efficiency of treatment, the pH of magnesium or calcium phytate solu- tion should be adjusted to 5.8-6.0. 1 Introduction Cellulose is one of nature’s more durable organic materials if stored at suitable conditions. This has been attested by numerous archaeo- logical textiles, which endured the test of time for more than two mil- lennia. Yet certain compounds, such as acids and transition metal ions, which are present in historical iron gall inks, dramatically reduce its stability, resulting in the loss of its mechanical properties. Unfortunately, iron gall ink, the most widely used ink from the Middle ages up to the 20 th century, contains both corrosive transition metals and acids, and may thus inflict severe damage to paper. 1 For several centuries, iron gall ink induced decay, referred to as ink corrosion, has been acknowledged as one of the major threats to the written cultural heritage. As early as 1765, the English chemist William Lewis published a treatise on the stability of iron gall inks and in 1898, the first conference was held the city of Sankt Gallen in Switzerland. 2 Several conservation practices have been used to stabilise endan- gered documents through the centuries. 3,4 The most effective aque- M O R A N A RTD d.o.o. e-PRESERVATIONScience