Advances in Storing and Monitoring Mercury-tin Amalgam Mirrors

ABSTRACT

Tin-mercury amalgam mirrors are ubiquitous amongst historical collections worldwide. They present potential human health risks as they degrade, releasing liquid mercury and mercury vapor. Over the last decade, care of degrading mirrors at Winterthur Museum, Garden & Library has evolved to their present storage: removing dripping mirrors from exhibition and into a limited-access storage space. Using a Jerome Mercury sensor, various methods for storage were evaluated for the buildup of mercury vapor. Mercury vapor accumulated within a plastic bag surrounding a dripping mirror, informing an open-design tray storage solution. While these trays catch drips at the source, they are open to ambient air to allow small volumes of vapor to dissipate. Updated practices for mirror storage, monitoring, and maintenance prioritize staff safety and object preservation.

RÉSUMÉ

Les miroirs « au mercure » (amalgame étain-mercure) sont omniprésents dans les collections historiques du monde entier. Ils présentent des risques potentiels pour la santé humaine lorsqu'ils se dégradent, libérant du mercure liquide et de la vapeur de mercure. Au cours de la dernière décennie, l'entretien des miroirs en cours de dégradation au Winterthur Museum, Garden & Library a évolué vers leur mode de stockage actuel, qui consiste à retirer des espaces d'exposition les miroirs qui suintent et à les placer dans un espace de stockage à accès limité. À l'aide d'un détecteur de mercure Jerome, différentes méthodes de stockage ont été évaluées au regard de l'accumulation de vapeur de mercure. L'accumulation de vapeur de mercure dans un sac en plastique enveloppant un miroir suintant a inspiré la conception d'un support de stockage ouvert. Bien que ces plateaux récupèrent les gouttes à la source, ils sont ouverts à l'air ambiant pour permettre à de petits volumes de vapeur de se dissiper. Ces nouvelles pratiques de stockage, de surveillance et d'entretien des miroirs donnent la priorité à la sécurité du personnel et à la préservation des objets. Traduit par Stéphanie Auffret.

RESUMO

Espelhos de amálgama de estanho-mercúrio são onipresentes entre as coleções históricas em todo o mundo. Eles apresentam riscos potenciais à saúde humana à medida que se degradam, liberando mercúrio líquido e vapor de mercúrio. Ao longo da última década, o cuidado com os espelhos degradados no Winterthur Museum, Garden & Library evoluiu para o armazenamento atual: removendo da exposição os espelhos que estavam “pingando” e colocando-os em um espaço de armazenamento com acesso limitado. Usando um sensor Jerome Mercury, vários métodos de armazenamento foram avaliados para o acúmulo de vapor de mercúrio. Vapor de mercúrio acumulado dentro de um saco plástico ao redor de um espelho pingando, forma uma solução que é armazenada por uma bandeja em ambiente aberto. Enquanto essas bandejas pegam gotas na fonte, elas ficam abertas ao ar ambiente para permitir que pequenos volumes de vapor se dissipem. Práticas atualizadas de armazenamento, monitoramento e manutenção de espelhos priorizam a segurança da equipe e a preservação de objetos. Traduzido por Beatriz Haspo.

RESUMEN

Los espejos de amalgama de estaño y mercurio son omnipresentes en las colecciones históricas de todo el mundo. Presentan riesgos potenciales para la salud humana a medida que se degradan y liberan mercurio líquido y vapor de mercurio. Durante la última década, el cuidado de los espejos degradados en el Winterthur Museum, Garden & Library ha evolucionado hasta su almacenamiento actual: se retiraron de la exhibición los espejos que gotean y se colocaron en un espacio de almacenamiento de acceso limitado. Usando un sensor Jerome Mercury, se evaluaron varios métodos de almacenamiento para la acumulación de vapor de mercurio. El vapor de mercurio se acumuló dentro de una bolsa de plástico que rodeaba el espejo que goteaba, informando así una solución de almacenamiento de bandeja de diseño abierto. Si bien estas bandejas atrapan las gotas en la fuente, están abiertas al aire del ambiente para permitir que se disipen pequeños volúmenes de vapor. Las prácticas actualizadas para el almacenamiento, monitoreo y mantenimiento de los espejos dan prioridad a la seguridad del personal y la preservación de los objetos. Traducción: Amparo Rueda.

KEYWORDS:

• Mercury
• amalgam mirrors
• looking glasses
• tin amalgam
• mercury vapor
• spill cleanup
• safety
• storage tray solution

Acknowledgements

The authors thank and ascknowledge Brandon Calitree for performing mercury measurements using the Jerome sensor, Bruno Pouliot for initiating the mirror monitoring program at Winterthur, and Kerith Koss Schrager for the valuable feedback on the content of this communication.

Disclosure statement

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

Notes

1 In a silvered-glass mirror, the reflective surface is a thin layer of metallic silver, deposited via the reduction of a silver nitrate solution. It is usually coated to avoid oxidation.

2 Text included in Collections Management Software when tin was detected using XRF: “Analysis suggests this object may contain mercury. Nitrile gloves and disposable lab coats should be used during handling. The object should be transported in display position, e.g., hanging, as lying flat could activate mercury movement. The transport cart should be covered with polyethylene to capture any mercury droplets that fall during movement. After movement is completed, the transport cart and new installation area should be checked with the raking light of a flashlight in a low light environment to detect potential spills on surfaces below (mercury droplets appear spherical in shape and will glisten in raking light). If droplets are detected on the transport vehicle, work surface or floor below the display area, notify conservation so that the spill can be collected. Do not attempt to clean up the spill on your own and do not vacuum the contaminated area.”

3 The Mercury Spill Control Station used by Winterthur Museum, Garden & Library was manufactured by Lab Safety Supply of Janesville, Wisconsin. The kit is no longer available for purchase in the United States due to a lack of SDS for the Mercury Amalgam powder supplied in the kit. A major benefit to this particular kit is the vacuum pump which is successful in capturing mercury droplets still on the object (see Figure 1) or those that have already fallen to surfaces below. Since the Lab Safety Supply Station is no longer available, the PIG Mercury Spill Vacuum Kit would be recommended. The kit comes with six vials for capturing loose mercury, so those vials are the expendable kit components that would need replacing, however it is unclear from the PIG website if replacements can be purchased.

Additional information

Notes on contributors

Marie Desrochers

Marie Desrochers, MS currently serves as the preservation outreach coordinator for the State of Utah's Division of Arts and Museums. Address: 617 E South Temple, Salt Lake City, UT 84102 USA. Email: [email protected].

William Donnelly

William Donnelly, MA is currently associate preventive conservator at Winterthur Museum, and affiliated assistant professor in the Department of Art Conservation, University of Delaware. Address: Winterthur Museum, Garden & Library, 5105 Kennett Pike, Winterthur, DE 19635 USA. Email: [email protected].

Melissa King

Melissa King, MS currently serves as the senior conservation liaison at Conserv, a preventive conservation technology company. Address: 114 Forest Street Westbrook, ME 04092 USA. Email: [email protected].

Rosie Grayburn

Rosie Grayburn, PhD is currently scientist and head of the Scientific Research and Analysis laboratory at Winterthur Museum, and affiliated associate professor in the Department of Art Conservation, University of Delaware. Address: as for Donnelly. Email: [email protected].