Transportation Environment Assessment
The rise in loans of cultural heritage artifacts between institutions has increased their exposure to the transportation environment. Though the duration of travel for a loaned artifact is usually brief and the artifact is buffered from the exterior environment by its packing case, the potential exists for exposure of the artifact to temperature and relative humidity conditions far exceeding the range designated by loan agreements, or episodes of shock and vibration among the greatest encountered in an artifact's lifetime. These environmental conditions may cause physical responses such as material expansion or contraction or impact from an extreme force that can damage an artifact (Michalski 1991). Further, an object's sensitivity to physical forces can vary depending on the temperature and moisture content of the constituted materials.
An object's transient period between venues represents an extension of the museum environment. The case in which an object is housed provides the primary buffer against exposure to extreme environments during transport. The permeability of materials used to construct the case and the method of case construction (i.e., tightness of seams, quality of gaskets) can reduce the rate of air exchange into the case and potentially limit the impact of the outside air on the interior environment of the case (Richard 1991). The use of packing material with low thermal conductivity can also slow changes in interior temperature. While the exterior case structure provides physical protection for the object, the use of isolation materials can reduce vibration and dissipate shock experienced by the object. (Marcon 1991).
Art packing and transportation has previously been an area of study, highlighted by the seminal Art in Transit conference in 1991, and this work has been instrumental in raising the level of packing worldwide. With the continued development of packing techniques and sensor technology, particularly with respect to shock and vibration, it is an opportune time to reassess the performance of packing cases currently in use.
In Situ Study: J. Paul Getty Museum
Though the majority of museums depend on assistance from outside consultants to pack museum artifacts for transport, large museums typically have experienced preparations staff with access to a range of suitable packing materials. The Preparations department at the J. Paul Getty Museum (JPGM) has earned a reputation for employing high-quality cases for the transport of loaned artifacts. They regularly use a double crate packing technique, particularly for three-dimensional pieces and panel paintings. This technique essentially houses an object inside an interior box that is then enclosed within an exterior box.
Within the transit case and at its base, Getty preparators also employ a range of cushioning foams common in the packing industry, as well as custom-designed Sorbothane rings that protect an artifact by absorbing shock and isolating and dampening vibration. The determination of how much isolation material to use within a case is typically based on the dimensions and weight of the object and the physical properties of specific cushioning materials reported by the manufacturer. However, verification of a material's ability to mitigate shock and vibration when in use is rarely conducted.
Therefore, an assessment of the environmental performance of these cases was developed.
Developing an Assessment Protocol
Working alongside the Preparations team, and conservation departments at the JPGM, the project team has conducted numerous in situ studies examining exterior and interior temperature, relative humidity, shock, and vibration conditions for a range of packing cases used by the JPGM to transport artifacts.
Many institutions monitor temperature and relative humidity inside packing crates during transportation of objects. What is unique about this research is that shock and vibration were logged simultaneously using accelerometers to examine dynamic forces when an artifact is in transit. There is the potential for exposure to extreme shock and vibration events during this transient period.
In the context of cultural heritage, accelerometers have been employed to examine shock and vibration of a structure subject to dynamic loads. These loads may include a range of activities, such as visitation, concerts, construction, or earthquakes. Recently, several examples of shock and vibration monitoring have been conducted by museums undergoing renovation, as there was concern about how construction activities would impact existing collections. (Johnson et al, 2013; Smyth et al, 2016). Deploying these sensors to crated objects in transit is allowing the project team to assess the effectiveness of a crate's construction in absorbing shock and isolating and dampening vibration.
Monitoring multiple packaged artifacts or mockups during the same transit also provides an opportunity to directly compare case performances when subject to identical environmental input conditions. While the bulk of monitoring occurs during ground or air transits, special attention is given to the so-called "first mile/last mile" transitions, as handling of packaged artifacts at either venue or at intermediate junctions is often thought to pose added risk of damage.
The environmental assessment protocol developed for this project will be made available to the field, allowing other cultural heritage institutions, to use it to assess their transit cases, particularly those which are commercially available.
Page updated: August 2017