Unveiling paper corrosive ink elements identity
Historical and legal documents contain indispensable information reflecting a significant part of our cultural heritage. These documents are under serious threat from natural causes of corrosive ink paper degradation. The need for the development of innovative conservation strategies has become apparent and world library and museums archivists are expressing an increasing interest in this direction. One of the most well known paper corrosives is iron gall ink. Its dark colour is due to the complex formation of ferric ion (in the form of sulphate iron complex) with tannins (plant or tree extracts). Its corrosive properties are attributed both to the degradative activity of sulphuric acid and iron ions on the support material. The catalytic action of iron ions on the hydrolysis of cellulose (paper's component) by sulphuric acid, results in the depolymerisation of cellulose and accounts for the papers' brittleness. Similar oxidative degradation is induced by other transition metals such as copper, also present in the natural raw material of iron gall ink. In order to apply the most appropriate conservation practice, the need to accurately identify the source of oxidative degradation is of key importance. To employ the best preservation method therefore requires either using preventive antioxidants radical scavengers or by neutralizing the acid. A multidisciplinary approach to improve the understanding of the ink's corrosive, underlying mechanism has been adopted. Its goal is to develop new and optimize current conservation practices has been followed. InkCor partners have been successful in the development and optimization of a simple method for performing iron and copper identification tests. By employing cutting-edge technology for elemental composition analysis researchers demonstrated the efficacy of their method. The findings give a new perspective in the evaluation and conservation of historical documents encouraging preparation of conservation plans.
