AIC's 53rd Annual Meeting

Conservators have employed numerous techniques and chemicals to remove discoloration and staining from paper objects. While other conservation specialties have utilized ammonium and sodium citrates as stain removers for decades, these are now beginning to see more widespread use in paper conservation. Citrates have shown promise as a tool to remove metallic impurities and staining while preserving the integrity of media and cellulose, however more information is desired. This panel brings together presentations addressing analytical research and theoretical considerations concerning the treatment of works on paper using citrates.

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.

The effects of ammonium citrate on calcium and iron levels in a 19^th century rag ledger paper
Crystal Maitland, Theresa J. Smith, Maeve Moriarty, Ute Henniges and Irene Brückle
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 19^th century leger 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.