By Foekje Boersma

In teaching preventive conservation, real-life examples are of great value. They expose students to the range of issues that must be considered when developing preventive conservation and management strategies for museum collections, buildings, and other cultural sites. The stakeholders involved in the decision making bring different kinds of expertise, experiences, and arguments to the table—all of which have to be borne in mind if preventive conservation strategies are to be successful and sustainable. There is not just a single approach to preventive conservation.

The Getty Conservation Institute's Education and Science departments are collaborating on a series of didactic case studies designed to illustrate the interrelated issues affecting the practice of preventive conservation and the decision-making process. The cases, describing actual museum situations, will present various scenarios for decision making and for balancing the requirements of the collection and the building with the mission, values, and operations of the museum. The case studies will be made available on the GCI's Web site, as well as on CD/DVD and in print format, and they will be applicable to classroom use in academic programs in conservation, museum studies, and architecture, as well as mechanical engineering and environmental studies. They will provide an important opportunity for students to explore the complexities involved in weighing options and making decisions, while exposing them to other professionals' areas of expertise. Experts already working in heritage preservation may also use the case studies as a source of information and reflection. The case studies can thus contribute to greater interdisciplinarity in the care and management of buildings, collections, and sites.

A Hidden Treasure in Amsterdam

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The first of the GCI case studies, currently in progress, deals with preventive conservation in the context of a rather remarkable historic house museum. In the old city center of Amsterdam lies Museum Ons' Lieve Heer op Solder (Our Lord in the Attic Museum), a house museum with an unusual name and history. On the outside it appears to be an ordinary seventeenth-century Amsterdam canal house. Inside it holds an unusual surprise—a Catholic church in its attic.

The property, located on a canal in Amsterdam's red-light district, dates to the early seventeenth century and is made up of three contiguous houses, connected at the upper stories. It is a typical Amsterdam merchant's house, characterized by top floors designed to serve as storage space for commodities.

Jan Hartman, a German Catholic who moved to Amsterdam to make his fortune in trade, bought the property in 1661. Extensive work on the house between 1661 and 1663 included not only the installation of a splendid, luxurious parlor (the Sael), but also a clandestine Catholic church, seating approximately one hundred fifty people and built in the attics of the contiguous houses.

Why create a Catholic church in the attic of a merchant's house in Amsterdam, and why did it have to be used clandestinely?

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In the sixteenth century, the Catholic Spanish Hapsburg royalty ruled the Low Countries, where Protestants, primarily Calvinists, formed a significant minority. The harsh measures installed by the Spanish kings caused increasing grievances, and in 1581, seven northern Dutch provinces declared their independence from the Spanish throne.

The same year, the new Dutch Republic officially forbade the open practice of the Catholic Mass. However, many Dutch Catholics remained faithful to the Catholic Church, and private churches were not unusual in the northern Netherlands in the seventeenth century. (The church in the attic, one of a number of such house churches in Amsterdam, is the only one still in use today.) Because of the religious tolerance at the time, clandestine churches were permitted, but they were not allowed to be recognizable from the street. Creation of the church, Ons' Lieve Heer op Solder, required major modification to the interior of the building—the structural floor beams carrying the fifth and sixth floors were cut in the middle to create an open space in the center and galleries along each side.

The hidden church was in use from about 1663 until 1887, when its much larger nearby successor, Saint Nicolas Church, was dedicated. That year, a group of Amsterdam Catholics who had formed the Amstelkring Foundation bought the building to save it from demolition. Museum Ons' Lieve Heer op Solder (formerly also known as Amstelkring) was opened to the public the following year.

Today this attractive merchant's house is still open to the public, and, apart from the church, several period rooms can be visited as rare surviving examples of their time. Since 1951, when Mass was reinstated at the church by a group of Amsterdam Catholic artists, the site has also been in use for weddings, baptisms, lectures, concerts, and special events.

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Research at the Site

The mission of the Our Lord in the Attic Museum—like that of many historic house museums—requires that preservation be balanced with access. Allowing visitation causes stress on the building and its collection—for example, the wear and tear on original wooden floors and stairs caused by visitor movement through the building, as well as the increased risks of unintentional damage to and theft of objects, which are on open display in the period rooms. Increasing visitor levels (ninety-two thousand in 2006) have challenged conservation efforts and also threaten visitor enjoyment, since rooms, hallways, and stairs in the building are relatively small and readily feel cramped.

One issue is the control of the indoor environment for visitor comfort and for the safekeeping of the collection and the building. In summer months—and especially during events in the church—indoor temperatures rise, and visitors feel uncomfortable and sometimes dizzy. In winter, severe condensation often occurs on the inside of the windows. Museum staff is interested in knowing more about how the indoor climate affects the collection and the building, and in learning if improvements can be made.

Visitor movement is also an issue. The routing through the building requires visitors to climb up and down steep and narrow stairs, which are common in this type of canal house. In view of the large visitor numbers, the museum is concerned about visitor safety and wear and tear on the building elements.

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In a collaborative project, the GCI and the Netherlands Institute for Cultural Heritage (ICN)—working with the museum's director Judikje Kiers and her staff—are studying the impact of visitors on the indoor environment of the building, on its interiors, and on its collections. As part of this work, options for management of the indoor environment are also being researched, in which visitor comfort is balanced with safe conditions for the preservation of the building and its contents.

The museum aims to keep alive the cultural and religious heritage of Catholic Amsterdam through care of the building and its associated collection. In addition, it wants to be a hospitable and inspiring meeting place where visitors can reflect upon and share their own religious and spiritual experiences. The museum's director recognizes that the Our Lord in the Attic Museum has an important role to play in current discussions of religious understanding and tolerance. For this reason, visits to this unique cultural site will likely increase in coming years, making it all the more necessary to determine a conservation and visitor management policy that supports the interpretive goals of the museum.

The underlying research of the GCI-ICN museum project encompasses investigation of present and past indoor climate conditions and research on the effect of current visitor levels and use on the indoor environment. Recent climate data were analyzed, and the rate of ventilation was established (with the assistance of the Technical University Eindhoven in the Netherlands); this information provided insights into the performance of the building. Using available historic meteorological records and informed estimates of visitor comfort levels in the past, the project team was able to approximate the indoor climate in the period before central heating was installed.

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In addition, an interdisciplinary team consisting of the museum's curators, the facility manager, an architect, two conservators, and two conservation scientists carried out a condition assessment in order to document the current condition of the building, its interior, and the collection, together with their susceptibility to agents of deterioration related to visitor levels. This assessment gave the team a better understanding of the performance of the building and of the type and extent of visitor-induced damage. It was, for example, found that the church has a relatively high air exchange rate, that the amount of wear and tear on the original wooden floors and stairs may indicate the original route of the churchgoers, and that there may be a correlation between damage in the building and the period when central heating was first installed (no measures were in place at that time to compensate for the related decrease in relative humidity during the winter).

Research into museum visitation and church attendance resulted in an approximate determination of the number of people that had gone through this building since the church was built. The total number of church visitors prior to 1887 is estimated at several million. Since the site became a museum, two million more people have visited the site, with annual visitor numbers steadily increasing. This information will be linked to the indoor climate and condition assessments.

Combined with an assessment of the museum's organizational environment (its mission, functions, resources, and institutional activities), the research generated a wealth of information, important for making informed decisions about building, collection, and visitor management.

The Case Study

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Information from the project's research will be used in the case study, which will address issues such as acceptable indoor climate limits for the building, the collection, and the visitors; visitor impact on the indoor environment; and the relationship between the number of visitors and mechanical damage to the collection and the building. The case study will also raise important questions: What is acceptable damage? Can—or should—a maximum visitor number or carrying capacity be established for the museum? What do the different experts mean when referring to protection, conservation, restoration, repair, and maintenance of both a building and its collection? How does the museum decide which action is appropriate? And finally, how does the public react to the message of the museum?

This particular preventive conservation case study, as mentioned, will be made available to academic programs through the GCI's Web site, as well as in CD/DVD and print format. It will also bring together information from literature, research, and practical experience in the field of historic house museum management. It will assist Our Lord in the Attic Museum and similar museums to determine manageable levels of visitation and use. Furthermore, it is intended to contribute to a better understanding between the different stakeholders involved in preserving a historic house museum: museum staff, architects, architectural conservators, collections conservators, conservation scientists, building and environmental engineers, visitors, local officials, and residents. Apart from the preservation of the tangible heritage, this case study will reflect on the importance of preserving intangible heritage by discussing the use of the church in its original function. Finally, it will concretely illustrate the decision-making process that can help create sustainable solutions to the problems of heritage management.

Foekje Boersma is a project specialist with GCI Education.