JAIC 2005, Volume 44, Number 3, Article 3 (pp. 175 to 183)
JAIC online
Journal of the American Institute for Conservation
JAIC 2005, Volume 44, Number 3, Article 3 (pp. 175 to 183)

THE EXHIBITION OF UNLACQUERED SILVER AT THE METROPOLITAN MUSEUM OF ART

PETE DANDRIDGE

ABSTRACT—The desire to inhibit the rate of tarnishing of silver objects has often led to their surfaces being coated with a lacquer or varnish; however, there are occasions when such a treatment would be inappropriate, either placing the object at risk physically or inhibiting the visual perception of its surfaces. Both concerns have been operative at the Metropolitan Museum of Art over the course of the last 25 years and have resulted in the implementation of several different approaches to the display of unlacquered silver. In each instance, these efforts were stimulated by the installation of different parts of the museum's collections, initially in the American Wing, followed by the Byzantine treasure from Attarouthi, and most recently, the medieval department's Early Christian and Byzantine silver. A common goal throughout has been to minimize the effects of gaseous pollutants on the silver by creating “clean” vitrines or storage cabinets, and then integrating into these spaces either passive or active systems to further reduce the levels of possible contaminants. The specifications for the vitrines and the techniques used for diminishing the gaseous pollutants evolved internally in conjunction with a growing body of research in preventive conservation focused on identifying both the harmful materials within exhibition and storage environments and the means by which a more benign environment might be achieved. A review of the decision-making which governed these various installations reveals a common approach which took into account a greater understanding of the dynamics of silver corrosion, and the introduction of new materials and methodologies with greater effectiveness in the adsorption of gaseous pollutants. The description of successes and failures in the implementation phase may benefit those faced with similar concerns in the exhibition of their collections.

TITRE—L'exposition de l'argent non verni au Metropolitan Museum of Art (musée d'art métropolitain). RÉSUMÉ—Le besoin de ralentir le rythme du ternissement des objets en argent a souvent eu comme conséquence l'application de vernis ou de laques sur leurs surfaces; cependant, il existe des situations pour lesquelles un tel traitement est inapproprié, soit en occasionnant un risque pour l'objet à vernir ou en diminuant la perception esthétique de ses surfaces. Ces deux préoccupations ont été en vigueur au Metropolitan Museum of Art au cours des 25 dernières années et ont conduit à la mise en application de plusieurs approches pour la présentation de l'argent non vernis. Dans chaque cas, ces efforts ont été stimulés par l'installation de différentes parties de la collection du musée, au tout début pour l'aile américaine, ensuite par le trésor byzantin d'Attarouthi et plus récemment, les pièces d'argenterie byzantines, des touts débuts de la Chrétienté et de la période médiévale. Tout au long de ce processus, l'objectif commun a été de minimiser les effets des polluants gazeux sur l'argent en créant des vitrines ou des cabinets d'entreposage “propres”, et d'y intégrer ensuite des systèmes actifs ou passifs pour réduire davantage le niveau de contaminants. Les spécifications des vitrines ainsi que les techniques utilisées pour diminuer les polluants gazeux ont progressivement évolué parallèlement avec plusieurs recherches en conservation préventive. Ces recherches avaient comme objectif, à la fois l'identification des matériaux dommageables dans les expositions et les réserves, ainsi que les moyens par lesquels un environnement plus acceptable pourrait être obtenu. Un examen du processus de décision qui a gouverné ces divers projets révèle une approche commune qui incorpore une bonne compréhension de la dynamique de la corrosion de l'argent, ainsi que l'introduction de nouveaux matériaux et des méthodologies présentant une meilleure capacité d'absorption des polluants gazeux. La description des succès et des échecs de notre mise en œuvre pourra être bénéfique pour ceux qui ont des préoccupations similaires lors de la mise en valeur de leurs collections.

TITULO—La exhibición de plata sin laca en Metropolitan Museum of Art (Museo Metropolitano de Arte). RESUMEN—El afán por inhibir la velocidad de ennegrecimiento de los objetos de plata a menudo ha llevado al recubrimiento de sus superficies con alguna laca o barniz; sin embargo, en ocasiones estos tratamientos podrían ser inapropiados, ya sea porque hacen peligrar al objeto físicamente, o porque inhiben la percepción visual de sus superficies. Ambas preocupaciones se han tomado en cuenta en el Museo Metropolitano de Arte a través de los últimos 25 años, y han resultado en la implementación de varios enfoques diferentes para la exhibición de plata sin laca. En cada instancia, estos esfuerzos fueron fomentados por la instalación de diferentes partes de las colecciones del museo, inicialmente en el American Wing (Ala Americana), seguida del tesoro bizantino de Attarouthi, y más recientemente, la plata del periodo cristiano temprano y bizantina del Departamento Medieval. Un propósito común en todos estos casos ha sido minimizar los efectos de contaminantes gaseosos en la plata mediante la creación de vitrinas “limpias” o armarios de almacenamiento, y luego integrar a estos espacios sistemas pasivos o activos para reducir aún más los niveles de los posibles contaminantes. Las especificaciones para las vitrinas y las técnicas usadas para disminuir los contaminantes gaseosos evolucionaron internamente en conjunto con un creciente aumento de investigaciones en el campo de la conservación preventiva, enfocado a identificar tanto los materiales nocivos que se encuentran dentro de los ambientes de exhibición y almacenamiento, como los medios para lograr un ambiente más benigno. Una revisión de las tomas de decisiones que rigieron estas distintas instalaciones revela un enfoque común, que tomó en cuenta un mayor entendimiento de las dinámicas de la corrosión de la plata y la introducción de nuevos materiales y metodologías con mayor efectividad en la adsorción de contaminantes gaseosos. La descripción de los éxitos y fracasos en la fase de implementación podría beneficiar a aquéllos que enfrentan preocupaciones similares en la exhibición de sus colecciones.

TÍTULO—Exposição de prataria não envernizada no Metropolitan Museum of Art (Museu Metropolitano de Arte). RESUMO—O desejo de inibir o grau de enegrecimento de objetos de prata muitas vezes levou a se cobrir suas superfícies com laca ou verniz; no entanto, há ocasiões em que este tipo de tratamento seria inadequado, seja por colocar o objeto fisicamente em perigo, ou por inibir a percepção visual de sua aparência. Ambas as preocupações foram examinadas no Metropolitan Museum of Art (Museu Metropolitano de Arte), no decorrer dos últimos 25 anos, e resultaram na implementação de diversas abordagens diferentes para a exibição de prataria não envernizada. Em cada caso, esses esforços foram estimulados pela instalação de diferentes partes das coleções do museu, inicialmente na ala americana, seguida pelo tesouro bizantino de Attarouthi e, mais recentemente, a prataria primitiva cristã e bizantina do departamento medieval. Um objetivo comum em toda parte tem sido minimizar os efeitos dos gases poluentes sobre a prata através da criação de vitrines “limpas” ou gabinetes de armazenagem, e depois integrando, dentro desses espaços, sistemas ativos ou passivos para ajudar a reduzir os níveis de possíveis contaminantes. As especificações para as vitrines e as técnicas usadas para diminuir os poluentes gasosos desenvolvidos internamente, em conjunto com um crescente aumento da pesquisa em conservação preventiva, focaram em identificar tanto os materiais nocivos dentro dos ambientes de exposição e armazenagem, como os meios pelos quais pode ser obtido um ambiente mais benigno. Uma revisão do processo de decisão que controla essas várias instalações revela uma abordagem comum que permitiu uma maior compreensão da dinâmica da corrosão da prata e a introdução de novos materiais e metodologias com maior eficácia na adsorção de poluentes gasosos. A descrição dos sucessos e fracassos na fase de implementação pode beneficiar aqueles que se defrontaram com preocupações similares na exposição de suas coleções.


1 INTRODUCTION

Over the past 50 years, conservators and conservation scientists have focused increasingly on identifying materials in the museum environment that contribute to the deterioration of works of art and the mechanisms by which they work. Much of the initial research was generated by the packing industry (Packman 1957, 1960; Rance and Cole 1958; Clarke and Longhurst 1961;Arni et al. 1965; Donovan and Moynehan 1965) with conservation scientists and conservators supplementing and refining the scope to reflect the specific needs and conditions of the museum community. The susceptibility of silver and metals generally to the effects of acidic pollutants generated by the materials used in their display and storage has been a subset of that research (Thomson 1965, 1978; FitzHugh and Gettens 1971;Weyde 1972;Oddy 1975;Blackshaw and Daniels 1978, 1979; Hnatiuk 1981; Leveque 1986; Berndt 1987; Craddock 1988; Brimblecombe et al. 1992; Green and Thickett 1994; Lee and Thickett 1996; Hatchfield 2002;Tétreault 2002). As a result, the understanding of the “ideal” macroand microenvironments for the exhibition of metals has grown substantively over time; however, economic and aesthetic concerns often inhibit museums' abilities to create the model environment. Such constraints have necessitated the development and institution of a variety of less costly but effective measures that are either object or exhibition case specific. A historical overview of the different approaches taken during the past 25 years by the Metropolitan Museum of Art to the exhibition of silver is illustrative of the techniques utilized by conservators to enhance the safekeeping of silver on display or in storage.


2 THE ERA OF LACQUER

Since at least the early 1950s, the principal form of protection for decorative and archaeological silver in the collections of The Metropolitan Museum of Art from the effects of contaminants in the air has been a coating of Agateen #27, a nitrocellulose lacquer, diluted with Agateen Thinner #1 and applied as a spray or by brush over a cleaned and degreased surface. Given its physical and optical properties, a properly applied coating can be an effective barrier (De Witte 1973-74; Heller 1983; Reedy et al. 1999); however, an excessive build-up of lacquer can diminish the reflectance of a burnished silver surface or impair the viewer's ability to accurately read finely chased or engraved details. Of further concern is the potential regular process of removal and reapplication necessitated by the effective lifespan of such a coating. While many objects are in stable enough condition to be treated repeatedly, there are other, more fragile pieces whose previous conservation treatments might be reversed by the action of the solvents or whose surfaces might be too sensitive for any mechanical agitation. By eliminating the need to lacquer silver, such problems can be avoided, as can the investment in time and resources repeated conservation would require.


3 THE AMERICAN WING

During the late 1970s and through much of the 1980s, The Metropolitan Museum of Art undertook a series of capital building projects to rehouse both the Egyptian and the American Paintings, Sculpture and Decorative Arts collections, as well as to install the Rockefeller Collection of Primitive Art. Coincident with the expansions in physical spaces was a philosophical change in the way the collections were to be exhibited. Not only were the most significant objects in the collection to be rehoused, but also those pieces that had previously been inaccessible would now be made available to the general public in areas adjacent to the main galleries.

Of particular interest for this study were the two different systems established in the American Wing for displaying silver without a coating (Weintraub 1981, 1988) in response to the two approaches taken by the curators for displaying the collection. In 1981, the principal silver objects were organized thematically around the balcony overlooking the Englehard Court in freestanding vitrines fabricated by Glasbau Hahn. The bulk of the collection was then installed for study and storage in 1988 in a distinct area, The Henry R. Luce Center for the Study of American Art, within two large, floor-to-ceiling cases. In both installations, all structural elements were specified as glass and metal both for aesthetic reasons and to avoid wood and wood products and their associated acidic vapors.

The vitrines around the balcony were designed to restrict the influx of outside air. The three glass panels that defined the sides and back of each vitrine were joined to one another with epoxy. The joins along each side were strengthened and warpage inhibited by overlaying the vertical edges of each panel with strips of glass similarly adhered. A gasketed sliding glass panel across the front provided access to the interior. The top and bottom edges of the glass panels slotted into metal channel associated with the metal framework for the light attic and the metal base of the vitrine. Design concerns necessitated that the interior shelves, blocks, and decks in the balcony cases be fabricated from MDO, exterior grade plywood with phenol-formaldehyde adhesive, and covered with a dyed cotton fabric. To counteract the acidic gases that might off-gas from the plywood and to provide a buffer against the influx of outside air, 3M strips of powdered, activated carbon cast out on a vinyl base were attached to the underside of all the shelves. The manufacturer changed the formulation of the strips early on to eliminate the plastic substrate and introduced Tarni-Shield with the activated charcoal embedded in a paper matrix.

The capacity of activated carbon to adsorb gaseous pollutants harmful to metals was understood early on in the packaging industry (Rance and Cole 1958). Its use was advocated by the conservation community initially as filters to be inserted into HVAC systems as a means of reducing the levels of outdoor pollutants allowed into the ambient air of the gallery (Thomson 1965, 1978; Garver 1968). The introduction of activated carbon as a passive sorbent for gaseous pollutants into the interior of vitrines appears to have first been suggested by Padfield (1966) and became the standard approach to the reduction of acidic gases in storage and display (Oddy 1975; Leveque 1986; Gilberg and Cook 1987; Craddock 1988; Druzik 1991; Weintraub and Wolf 1995; Lee and Thickett 1996).

While the Luce Center was under construction, the silver not on display was stored, unlacquered, in interior metal and glass cabinets equipped with externally mounted, positive pressure systems to supply conditioned air to the interior of the cases (Weintraub 1981) at a flow rate sufficient to restrict the intrusion of outside air. The pump was installed adjacent to the case and pushed a steady supply of ambient air through Tygon tubing into the cases. Inline canisters of silica gel and Purafil, a potassium permanganate and alumina-based material, controlled the relative humidity and adsorbed gaseous pollutants. An advantage of the Purafil over the activatedcarbon was that it was self-indicating, changing color when its saturation point was reached.

When the Luce Center was completed and the silver moved from the storage cabinets to its permanent home, the silica gel component was eliminated from the system, and larger pumps were utilized to accommodate the more generous, open spaces. The silver was displayed both on glass shelves and on formed metal shelving with a baked-on powdercoated finish. Brush gaskets adhered to the edges of the adjoining glass panels allowed the pressure to equalize.

In evaluating the two systems, an obvious appeal of the use of a passive approach was its lack of dependence on a mechanical system, but it placed a premium on the relative exclusion of outside air, the creation of an interior vitrine environment that was non-reactive, and the regeneration or replacement of the adsorbent prior to its saturation point. Depending on the surface area of the sorbent and the presence of other surfaces that might scavenge pollutants, the exhibition silver can act as a sink for hydrogen sulfide (Parmar and Grosjean 1989, 1991; Druzik 1991) such that tarnishing may eventually initiate. The experience in the American Wing seems to bear this out in that the silver has shown visual indications of sulfide tarnish, albeit at a slower rate than if no adsorbent were present.

Several factors have inhibited the success of the positive pressure system. The constant cycling of the pumps, and their sizing relative to the resistance of the tubing surface and the sorbent, necessitated their replacement every two years. Of equal concern was that the noise generated by the pumps was considered to compromise the visitor's experience. Since there was no alternative space for the pumps' installation, their use has been discontinued and a system of passive adsorption with canisters of activated carbon substituted; however, the size of the cases, the relatively minimal surface area of the sorbent, and the ease with which ambient air can enter the display area have all limited the protection afforded the silver.


4 THE ATTAROUTHI TREASURE

In 1986, the museum acquired the Attarouthi Treasure, a group of sixth-century, Byzantine, partial gilt, silver, repoussé objects including chalices, censers, and a Eucharistic dove in such a state of preservation that they came close to representing the original surface quality intended by the goldsmiths (Dandridge 2000). As documents of the visual aesthetic current at the time, it was important to present them to the public and scholars in as unblemished a state as possible. Further, the fragility of the gilded surfaces in discrete areas on the chalices had necessitated localized consolidation with Paraloid B-72, an ethyl methacrylate and methyl acrylate copolymer, precluding their being lacquered and subsequently cleaned without potential disruption and loss of the reattached gold leaf.

In preparing the specifications for a vitrine to house the treasure, elements of both design schemes utilized in the American Wing were adopted while incorporating several new products and introducing an active, recirculating, filtration system. Hahn fabricated the vitrine with the display area a box of glass and metal with a volume of sixty-four cubic feet, supported by a wooden base, with light supplied externally from an attic overlaying the glass top. Apart from the front panel that provided access to the interior, all glass-to-glass and glass-to-metal joins were secured via aluminum channel with inset silicone gasketing. As supplied, the contact between the front panel and the glass sides was not gasketed, and due to the size of the glass, the panel exhibited a slight bow. To provide a gasket and to close the space created by the bow, a bead of clear, neutral cure silicone caulk was run into the gaps down either side of the panel. Once cured, each bead was sliced through its center to allow the door to be opened and closed. Interior decks and blocks were made from extruded, high-density polyethylene foam, a product utilized in the packaging industry and suggested by Blackshaw and Daniels (1978) as a material appropriate for the storage of objects. A distinct advantage of the material as supplied by Sentinel Foam Products was that it was produced in plank form in a variety of densities. The 9PCF weight was selected since it could be shaped with woodworking tools, joined mechanically with screws, and allowed for fabric coverings to be attached with staples, eliminating any need for glue. Depending on the thickness of the material, it can distort under the strain of stretched fabric; however, this characteristic can be offset by attaching the foam to more rigid materials such as aluminum channel, L-bracket, metal sheeting, or Plexiglas. In this instance, the full two-inch depth of the material could be accommodated for the backing board and required no auxiliary support. The interior label copy was adhered with wheat starch paste to eight-ply acid-free ragboard. All materials had either been approved for permanent exhibition by the Getty Conservation Institute (1989) or by means of the Oddy test (1975) at The Metropolitan Museum of Art.

Two different approaches were investigated to actively condition the air within the vitrine, the reduction of the relative humidity to levels sufficiently low to inhibit the production of silver sulfide, and the elimination of hydrogen sulfide and other acidic vapors with an adsorbent. Michalski (1982, 1985) and Toogood and Wilson (1985) had designed modules that constantly reconditioned the air within a vitrine to a predetermined relative humidity. While successful, both systems contained multiple mechanical elements and required an adjacent space for installation not available in the Byzantine gallery. Given the inert quality of all of the vitrine materials and an ambient relative humidity of 40–50% in the galleries, it seemed more appropriate and practical to implement the second approach and focus on purging the atmosphere within the vitrine of those organic acids known to be most deleterious to silver.

The research undertaken by Parmar and Grosjean (1989, Parmar and Grosjean 1991) to study the effectiveness of sorbents in removing atmospheric pollutants from the exhibition environment quantified for the first time the relative capacity of a variety of sorbents including Purafil and activated carbon to successfully adsorb hydrogen sulfide in both the passive and active mode. For adapting an active system of filtration within a vitrine, they suggested using a fish tank pump in conjunction with a canister of activated carbon. Their system was adapted and a fish tank pump was installed in the base to constantly circulate the air in the display area through Tygon tubing and an in-line canister filled with 200 grams of activated carbon. A 12-20 mesh size was selected for the sorbent to maximize the surface area for adsorption, and at the same time minimize both the drag on the flow of air through the canister and the migration of dust into the exhibition space. A loose packing of cotton wool in the supply side of the filter served as a catch for any particulates. The tubing was inserted through holes drilled in the aluminum base of the bonnet with the voids around the tubing filled with a neutral cure silicone caulk. The minimal noise and vibration of the pump were dampened by the plywood surround of the base and by setting it into a foam box.

Since there is no visual indication of when activated carbon has reached its saturation point, an alternate means of evaluating conditions within the vitrine needed to be found. No active or passive monitors were available for detecting hydrogen sulfide at the levels that might affect silver. Blackshaw and Daniels' (1979) analysis of the relative rates of corrosion of different silver alloys indicated that polished blanks of sterling silver were more reactive than pure silver as well as comparable alloys worked in a more traditional manner. Two polished blanks of sterling silver were placed on the deck adjacent to the ports for air supply and return with one half of each blank brush coated with two applications of Agateen #27 diluted in Agateen Thinner #1. An arbitrary time frame of one year was scheduled for the replacement of the sorbent. The condition of the silver surfaces was monitored on a regular basis and over the course of the next nine years no visual change was perceptible either on the blanks or on the surfaces of the objects. While no data log was recorded for the relative humidity levels within the vitrine, periodic measurements in the gallery confirmed the expected range in ambient conditions of relative humidity, broken only by slight fluctuations at points of seasonal transition.


5 THE MARY AND MICHAEL JAHARIS GALLERY

In 2000 the medieval department's Early Christian, Byzantine, and Migration period collections were reinstalled in the newly designed Mary and Michael Jaharis Gallery. The changes in the exhibition space necessitated the fabrication of entirely new vitrines. Given the richness of the museum's collection of Early Christian and Byzantine silver and silver gilt archaeological objects and their variable states of preservation, it was an opportune moment to evaluate the system utilized for the Attarouthi Treasure and to consider expanding it to all of the vitrines exhibiting silver objects.

A principal goal underlying the new design for the Jaharis gallery was to open up and accentuate the shallow arches articulating the walls of the galleries. The vitrines, similarly sized to the original Attarouthi display, were suspended within the arches and projected slightly forward and to the sides, and were fabricated from aluminum sheet, 3/8 in. thick, with U-channel welded on for the insertion of the glass sides and top. Mechanical attachment was utilized for all metal-to-metal joins. Prior to assembly, 3/4 in. extruded polyethylene planks were attached to all interior metal surfaces with an epoxy adhesive and then fabric covered. Where increased strength was required for the mounting of heavy objects from the back panel, vertical aluminum posts were secured down the length of the reverse. All metal-to-metal joins were sealed with silicone, and glass-to-metal joins were gasketed. The angled support for the label copy across the front of the vitrine was powdercoated aluminum with the label copy itself adhered with 3M double-sided, laminating adhesive #465 to a thin sheet of Sintra Material, a rigid, closed-cell, polyvinyl chloride board. All of the materials used were tested in-house by the modified Oddy test (Bamberger et al. 1999).

When the original vitrine displaying the Attarouthi Treasure was deinstalled prior to the objects' incorporation into the Jaharis gallery, the pump's rubber diaphragm was found to have deteriorated, significantly reducing its effectiveness. An online search of small, special-purpose pumps, built to a higher material and operational standard, led to the selection of a miniature brushless pump in a sealed housing produced by Brailsford, incorporating diaphragms made either of Viton, a fluoroelastomer, or EPDM, an ethylene propylene diene monomer, both of which the manufacturer suggested replacing on a yearly basis due to possible fatigue. In discussions with Brailsford, Viton was chosen given its slightly greater stability; however, there is the potential for some minimal off-gassing from the diaphragm. That potential risk was acceptable given that the air within the display area of the vitrine is circulated within a relatively closed system. Any possible contaminants that might be given off by the pump's diaphragm, or diffuse into the air within the vitrine from the gallery will be filtered immediately in the case of the Viton or will be diluted by the conditioned air in the display area and eventually scrubbed by circulating through the filter. Indeed, the system had effectively mitigated any pollutants generated by the deteriorated rubber diaphragm in the initial installation. While the pumps are described as quiet, their installation in vitrines comprised only of glass and metal necessitated further reduction of the vibration to reduce the noise to acceptable levels. To add dampening mass, the pumps were attached to a thick plate of Plexiglas to adsorb vibration, and small feet of high density polyethylene were adhered to the bottom of the plate to reduce the surface area in contact with the vitrine.

Continuing research on adsorbents for gaseous pollutants has been limited. A study by Bradley 1989 at the British Museum led to the introduction of zinc oxide pellets as passive scavengers in their vitrines displaying silver. Several conservation-specific materials, Scavengel and MicroChamber were produced that incorporated different sorbents into plastic or paper matrices with a significant component of each being activated carbon. While these materials were considered, the proven ability of activated carbon to adsorb gaseous pollutants, the efficiency of a filter containing only sorbent, and the successful implementation of the system in the initial Attarouthi installation led to the continued use of activated carbon in the circulating filtration systems incorporated into the vitrines for the Jaharis gallery.

The need to be able to monitor the levels of contaminants within museums and vitrines had stimulated the development of both passive and active techniques for the detection of formaldehyde and other pollutants (Grzywacz and Stulik 1991; Landry et al. 1991; Martin and Blades 1994; Grzywacz and Tennent 1994); however, a means for the detection of hydrogen sulfide had not yet been addressed and led to the reintroduction of polished sterling silver blanks into the vitrines as visual indicators. The diaphragms and charcoal are changed on a yearly basis with pump failure monitored regularly in passing through the gallery. To date, the silver has shown no indication of tarnishing.


6 CONCLUSION

The need to display silver objects without having to lacquer them has led to the fabrication of a group of sealed vitrines from materials selected to create a benign interior environment. The inclusion of an active filtration system in the design provides a significant degree of protection against pollutants from external sources and from any which might be offgassing from the vitrine materials. The system has functioned successfully for fifteen years in the instance of the Attarouthi Treasure. What is not clear is whether a passive system of adsorption utilizing either activated charcoal or another of the sorbents now being tested (Ankersmit et al. 2000) would be equally successful given the relatively inert environment of the vitrine. Recent developments in accurately recording the dose of hydrogen sulfide or carbonyl sulfide within a closed space (Ankersmit et al. 2000) may help to clarify the question. Certainly, the minimal cost of an active filtration system provides a measure of assurance, as well as providing a potential means for exhibiting unlacquered silver in vitrines built more economically and to different standards.


ACKNOWLEDGEMENTS

The author would like to acknowledge the generosity of the Getty Conservation Institute for making available the results of their material testing; the efforts of Tom Vinton, Principal Departmental Technician in the Medieval department for his assistance in the maintenance of the filtering systems; and the support of Helen Evans, Curator, Department of Medieval Art, Frances Safford, Associate Curator, Department of American Decorative Arts, George Wheeler, Research Chemist, Department of Scientific Research, and Lawrence Becker, Sherman Fairchild Conservator in Charge, Sherman Fairchild Center for Objects Conservation.



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AUTHOR INFORMATION

PETE DANDRIDGE is Conservator in the Sherman Fairchild Center for Objects Conservation, where he began working in 1979. He received his MA in conservation and a certificate of advanced studies from the Cooperstown Graduate Program in the Conservation of Historic and Artistic Works of Art. Since 1984, he has had primary responsibility for the ivories, enamels, and metalwork in the collections of the Department of Medieval Art and The Cloisters. He has published and lectured on Byzantine ivories, the gilding of silver in Byzantium, Early Christian and Migration Period jewelry, Limoges enamels, medieval aquamanilli, and related subjects. Address: Sherman Fairchild Center for Objects Conservation, The Metropolitan Museum of Art, 1000 Fifth Ave., NewYork, NY 10028; pete.dandridge@metmuseum.org

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