The disastrous copper. Comparing extraction and chelation treatments to face the threat of copper-containing inks on cellulose

Sara Zaccaron; Antje Potthast; Ute Henniges; Johannes Draxler; Thomas Prohaska; Patricia McGuiggan

doi:10.1016/j.carbpol.2018.10.075

The disastrous copper. Comparing extraction and chelation treatments to face the threat of copper-containing inks on cellulose

Carbohydr Polym. 2019 Feb 15:206:198-209. doi: 10.1016/j.carbpol.2018.10.075. Epub 2018 Oct 26.

Authors

Sara Zaccaron¹, Antje Potthast², Ute Henniges³, Johannes Draxler⁴, Thomas Prohaska⁵, Patricia McGuiggan⁶

Affiliations

¹ Johns Hopkins University, Sheridan Libraries and University Museums, Heritage Science for Conservation, 3400 North Charles Street, Baltimore, MD 21218, United States. Electronic address: sara.zaccaron@boku.ac.at.
² BOKU, University of Natural Resources and Life Sciences, Vienna, Department of Chemistry, Division of Chemistry of Renewable Resources, Muthgasse 18, A-1190 Vienna, Austria. Electronic address: antje.potthast@boku.ac.at.
³ BOKU, University of Natural Resources and Life Sciences, Vienna, Department of Chemistry, Division of Chemistry of Renewable Resources, Muthgasse 18, A-1190 Vienna, Austria. Electronic address: ute.henniges@boku.ac.at.
⁴ BOKU, University of Natural Resources and Life Sciences, Vienna, Department of Chemistry, Division of Analytical Chemistry, Konrad Lorenz-Straße 24, A-3430 Tulln an der Donau, Austria. Electronic address: j.draxler@gmx.at.
⁵ BOKU, University of Natural Resources and Life Sciences, Vienna, Department of Chemistry, Division of Analytical Chemistry, Konrad Lorenz-Straße 24, A-3430 Tulln an der Donau, Austria. Electronic address: thomas.prohaska@boku.ac.at.
⁶ Johns Hopkins University, Sheridan Libraries and University Museums, Heritage Science for Conservation, 3400 North Charles Street, Baltimore, MD 21218, United States; Johns Hopkins University, Whiting School of Engineering, Department of Materials Science and Engineering, 3400 North Charles Street, Baltimore, MD 21218, United States. Electronic address: mcguiggan@jhu.edu.

PMID: 30553313
DOI: 10.1016/j.carbpol.2018.10.075

Abstract

Iron gall inks are known to be detrimental to the permanence of historic documents. Among the transition metals present, copper is the greatest threat and an open challenge due to the lack of Cu-specific treatments. In this study, we address the inhibition of copper by comparing extraction (a newly proposed glucose-based treatment) vs. chelation (phytate-based) approaches in terms of performances in scavenging copper and slowing the degradation rate, and of possibly induced side effects. Results show that the glucose treatment partially extracts copper, but it causes long-term damages to paper, i.e. increased fragility and discoloration. The phytate protocol was found beneficial in inhibiting the catalytic activity of copper-rich inks. It limits both long-term oxidation and hydrolytic breakdown of samples without compromising the visual appearance.

Keywords: Calcium phytate; Cellulose; Copper-catalysed degradation; Iron-gall inks; Oxidation; Reducing sugars.