Using a PH-adjusted Semi-rigid Agarose Gel with Ion Exchange Resin for Poultice Desalination: Preliminary Experimentation and Case Studies

ABSTRACT

Many highly unstable, actively crumbling and/or spalling objects cannot withstand desalination by repeated immersion in water baths. Alternative poultice treatments can be more difficult to monitor and less effective at removing soluble salts. Historically, objects too fragile to undergo desalination have been stored in climate-controlled enclosures, which can present maintenance challenges and often prevent examination or display. This paper presents a review of recent gel-based desalination approaches and brief experiments on an innovative method to remove soluble salts from extremely fragile porous materials using a pH-adjusted agarose gel mixed with an ion exchange resin. A pilot application led to experimental modifications and the development of the treatment protocol used in this case study. Process and results are described along with suggestions for further research.

RÉSUMÉ

De nombreux objets instables présentant des pertes de cohésion et des soulèvements ne peuvent supporter un traitement de dessalement par immersion répétée en bains aqueux. Des traitements alternatifs par compresses peuvent être plus difficiles à contrôler et moins efficaces pour le retrait des sels solubles. Historiquement, les objets trop fragiles pour subir un dessalement ont été conservés dans des enceintes au climat contrôlé, qui peuvent être compliquées d'entretien et souvent empêcher l'examen ou l'exposition des pièces. Cet article présente une revue des approches récentes de dessalement par gel, et de courtes expériences sur une méthode innovante pour le retrait des sels solubles de matériaux poreux extrêmement fragiles, grâce à l'utilisation d'un gel d'agarose au pH ajusté, associé à une résine échangeuse d'ion. Une application pilote a mené à des modifications expérimentales et au développement du protocole de traitement utilisé dans cette étude de cas. Le processus et les résultats sont décrits, ainsi que des suggestions de recherches supplémentaires. Traduit par Claire Cuyaubère.

RESUMO

Muitos objetos altamente instáveis, ativamente desmoronando e/ou fragmentando não podem resistir à dessalinização por imersão repetida em banhos de água. Tratamentos alternativos de cataplasma podem ser mais difíceis de monitorar e menos eficazes na remoção de sais solúveis. Historicamente, objetos frágeis demais para serem submetidos à dessalinização são armazenados em recintos climatizados, o que pode apresentar desafios de manutenção e, muitas vezes, impedir o exame ou a exibição. Este artigo apresenta uma revisão das recentes abordagens de dessalinização à base de gel e breves experimentos sobre um método inovador para remover sais solúveis de materiais porosos extremamente frágeis usando um gel de agarose com pH ajustado misturado com uma resina de troca iônica. Uma aplicação piloto levou a modificações experimentais e ao desenvolvimento do protocolo de tratamento utilizado neste estudo de caso. O processo e os resultados são descritos juntamente com sugestões para novas pesquisas. Traduzido por Francisco Vieira.

RESUMEN

Muchos objetos muy inestables, que se desmoronan y/o desconchan activamente, no resisten la desalinización mediante inmersión repetida en baños de agua. Los tratamientos alternativos con cataplasmas pueden ser más difíciles de controlar y menos eficaces para eliminar las sales solubles. Históricamente, los objetos demasiado frágiles para someterse a la desalinización se han almacenado en recintos de clima controlado, lo que puede plantear problemas de mantenimiento e impedir a menudo su examen o exposición. Este artículo presenta una revisión de los enfoques recientes de desalinización basada en gel y breves experimentos sobre un método innovador para eliminar sales solubles de materiales porosos extremadamente frágiles utilizando un gel de agarosa con pH ajustado mezclado con una resina de intercambio iónico. Una aplicación piloto condujo a modificaciones experimentales y al desarrollo del protocolo de tratamiento utilizado en este estudio de caso. Se describen el proceso y los resultados, junto con sugerencias para futuras investigaciones. Traducción y revisión: Ramón Sánchez y Vera de la Cruz; revisión final: Amparo Rueda e Irene Delaveris.

KEYWORDS:

• Conservation
• poultice desalination
• agarose
• ion exchange resin
• archaeological objects
• limestone
• ceramics
• soluble salts

Acknowledgements

Thank you to the Southeast Regional Conservation Association, and indirectly, the University of Delaware Art Conservation Department, for respectively organizing and supporting the 2018 Annual Meeting Workshop, which promoted the invaluable exchange of ideas that shaped our approach for this project. Particular thanks to Bill Size, Emeritus Professor of environmental sciences at Emory University, for his ongoing assistance with geology-related analysis and interpretation, and to John Bacsa, Facilities Director of the Crystallography Lab at Emory University, for his help with XRD analysis. Thanks to Melinda Hartwig, curator of ancient Egyptian, Nubian, and Near Eastern art at the Carlos Museum for her curatorial guidance, and to the Exhibition Design Department at the Carlos Museum for their assistance with making trays in planning for and moving of the stela. Thanks to Stephanie Watkins of Watkins Conservation Services, LLC, for offering practical advice and correspondence. Many thanks to Carlos Museum conservation team members Kaitlyn Wright, Advanced Mellon Fellow in Object Conservation; Elena Bowen, former graduate intern; Clara Gonzalez, pre-program intern; and Anna Connolly, undergraduate intern; all of whom provided feedback and an extra set of hands whenever needed. We are especially indebted to the Andrew W. Mellon Foundation whose generous funding made this project possible.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Andrew W. Mellon Foundation.

Notes on contributors

Brittany Dolph Dinneen

Brittany Dolph Dinneen is assistant conservator of objects at the Michael C. Carlos Museum, Emory University and a Professional Associate of AIC. She has previously worked at the National Museum of African Art, National Museum of American History, and the Kelsey Museum of Archaeology. Additionally, she has carried out archaeological conservation work for projects in Jordan, Azerbaijan, and Greece, where she is currently a senior team member of the American Excavations Samothrace. She received her master’s degree from the UCLA/Getty Program in Conservation of Cultural Heritage, following a bachelor’s degree in anthropology with a focus on archaeology. Address: Michael C. Carlos Museum, Emory University, 571 South Kilgo Circle, Atlanta, GA 30322, USA. Email: [email protected].

Jessica Betz Abel

Jessica Betz Abel is a trained objects and architecture conservator specializing in the treatment, reconstruction, and installation of monumental objects. Jessica was previously a conservator at the Penn Museum of Art and Archaeology working on the reinstallation of the Ancient Egyptian and Nubian Galleries. She has also worked as a conservator at the Museum of Modern Art, the Smithsonian Museum Conservation Institute, the Hirshhorn Museum and Sculpture Garden, and the Carlos Museum. Additionally, she has conducted archaeological conservation work in Turkey and Greece. Jessica holds a master's degree in Conservation from Columbia University as well bachelor's degrees in Art History and Studio Art. Jessica joined the V&A in September of 2023 as the Conservation Operations Manager. Address: Victoria & Albert Museum, Cromwell Road, London SW7 2RL, UK. Email: [email protected].

Renée Stein

Renée Stein is chief conservator at the Michael C. Carlos Museum at Emory University where she oversees the treatment, preventive care, and technical analysis of the Museum’s diverse collections. Stein is also Associate Teaching Professor in the Art History Department and teaches courses on conservation and technical study. She received a Master of Science specializing in objects conservation from the Winterthur  – University of Delaware Program in Art Conservation. She is a Fellow of the American Institute for Conservation of Historic and Artistic Works and has been recognized with the Sheldon and Caroline Keck Award for outstanding mentoring. Address: Michael C. Carlos Museum, 571 S Kilgo Circle, Atlanta, GA 30322, USA. Email: [email protected].