AIC's 53rd Annual Meeting

Conservators have employed numerous techniques and chemicals to remove discoloration and staining from paper objects. While ammonium and sodium citrates have long been utilized as cleaning agents by other conservation specialties, they have been gaining traction in paper conservation. Citrates show particular promise for removing metallic impurities and staining while preserving the integrity of both media and cellulosic supports. However, additional
research and practical knowledge are needed to fully understand their safe application.

This panel brings together presentations that explore recently published analytical research, treatment case studies, and theoretical considerations regarding the use of citrates in the treatment of works on paper. Three short presentations will be followed by ample time for questions and discussion of emergent approaches to treatment using citrates. The collaborative dialogue will serve as a springboard for identifying critical gaps in current knowledge and generating innovative research directions to advance our understanding of citrate applications in paper conservation.

The effects of ammonium citrate on calcium and iron levels in a 19th century rag ledger paper
Crystal Maitland, Senior Conservator of Paper at the Winterthur Museum, Garden & Library, Affiliated Professor for the Winterthur/University of Delaware (WUDPAC) program
Theresa J. Smith, Associate Professor of Paper Conservation in the Patricia H. and Richard E. Garman Art Conservation Department at SUNY Buffalo State University
Maeve Moriarty, Senior Conservation Scientist, Canadian Conservation Institute
Ute Henniges, Academic Staff Member, Stuttgart State Academy of Art and Design
Irene Brückle, Professor and Head of the Program Conservation of Works of Art on Paper, Archival and Library Materials program at the Stuttgart State Academy of Art and Design

Highlighting the inorganic analysis of work recently published in JAIC,* this talk will examine data gathered into the effects of immersion treatments with solutions of ammonium citrate (pH 5.5; pH 8.5) and citric acid (pH 1.8) on the calcium and iron levels and distribution in a 19th century ledger paper, both with and without a secondary calcium bicarbonate deacidification step. As ammonium citrates are chelating agents capable of binding both calcium and iron ions we used X-ray diffraction (XRD), scanning electron microscopy/energy dispersive X-ray spectrometry (SEM-EDX), scanning X-ray fluorescence (XRF) and inductively coupled plasma mass spectrometry (ICP-MS) to examine how the distribution of calcium and iron changed with treatment. Despite the brightening effects measured in the paper, in our data we saw very little change in iron levels for any of the treatments tested. The three chelating solutions removed significantly more calcium than the other wash solutions; some calcium was reinstated by the calcium bicarbonate treatment step. There was no statistically significant variation in either the calcium or iron levels achieved by changing the pH of the citric acid or citrate solutions.
* Venus, Philine, Ute Henniges, Irene Brückle, Crystal Maitland, Theresa J. Smith, Maeve Moriarty, Kamila Bladek, Diogenes Vedoy, and Antje Potthast. 2025. “Testing Ammonium Citrates for Enhanced Washing of Paper.” Journal of the American Institute for Conservation, March, 1–20. doi:10.1080/01971360.2025.2464337.

A citrate retrospective
Madison Brockman, Paper Conservator, Los Angeles Art Conservation

Madison Brockman will present treatment case studies featuring citrates used with gels, in combination with oxidative and reductive bleaches, and citrates used in an overall aqueous treatment solution. Madison will present some successes and limitations when treating different kinds of discoloration on paper and media types, considerations when sourcing and disposing of citrates in private practice, and other tips and tricks for practical use. This presentation will also briefly touch on an accelerated aging study previously published in the WAAC newsletter and an informal exploration of the effects of citrates on friable media.

Why do citrates work?
Sarah Bertalan, Conservator of Works on Paper, New York NY

Citrate treatments succeed because they address the unstable inorganic content of modern papers. The additives in papers are well known, however, paper conservators tend not to consider them when discussing condition and treatment. The pigment and mineral additives in modern papers react when exposed to high or fluctuating humidity, daylight and changing pH. These reactions noticeably alter the appearance of works of art. This brief presentation focuses on the use of inorganic additives in modern paper manufacture and their behavior over time.