Since March 2024, an outstanding selection of lacquer objects from Japan and Korea as well as red carved lacquer works and archaeological lacquers from China have been on display at the Linden Museum. The occasion was the reopening of parts of the permanent exhibition on East Asia, for which the lacquer cabinet was also re-established.
However, before the individual objects could be placed in their final position in the display cases by the conservator in charge, important preparatory conservation measures were necessary in advance, which are explained in more detail below.
In simple terms, East Asian lacquer objects consist of the resin of the lacquer tree (rhus vernificera), which is applied in many thin layers to a carrier, e.g. made of bamboo or wood, after extensive preparation and then cured under high humidity. The varnish can be colored by adding pigments and elaborately incorporating them. For example, the addition of cinnabar gives the lacquer a red color and the addition of iron oxide gives it a black color. The surfaces of the objects are often elaborately designed. An outstanding example of this is the technique of inlay work, which is applied to the top layers of lacquer in geometric or floral shapes using thin plates of mother-of-pearl, metal foil, tortoiseshell or ivory and can be executed to absolute perfection.
If different materials are combined on an object, this means that each material used has different material properties and reacts differently to fluctuating humidity and temperature values. Strongly fluctuating climatic values in the environment can cause the varnish to expand or contract differently to the inlay work, which triggers stresses in the material and can cause irreversible damage, such as small cracks in the object. Defects or cracks on the object that extend to the wooden core also represent a point of attack.
Based on this knowledge, the climate values of the exhibition showcases had to be adjusted to the climate values in the depot before the painted objects were removed from the depot. Using a built-in device to regulate the humidity in the display cases, it was possible to gradually achieve an equalization of the values in the depot and in the display cases. A digital data logger was used to closely monitor the climate over the entire period. Once the climate curves had stabilized, the lacquer objects were moved from the depot to the display cases in the lacquer cabinet.
Many lacquer objects from the collection of the Linden Museum are packed in the depot in a customized wooden box with a lid made of kiri wood (jap. tomobako), which in turn is fitted exactly into a larger wooden box. The object in the innermost wooden box is wrapped in a silk cloth. Each wooden box is secured with a ribbon that closes the box with a so-called butterfly knot (jap. himokake). As long as the object is inside the crates, this traditional packaging ensures a stable internal climate thanks to the double crate walls, which only adapts to the external climate in the long term.
For the new presentation of the lacquer cabinet, however, it was necessary for the selected lacquer objects to leave their protective packaging. Even though the temperature and humidity values were almost identical at the time of the object installation, the lacquer objects, which have their own traditional packaging, were to be slowly acclimatized for safety’s sake. For this purpose, the objects were placed in their sealed packaging in the display cases for a longer period of time. The inner box with the object was then placed on top of the closed outer box and left in the display case for a further period of time. The inner box lid was then opened, placed on the edge of the box in an offset position and again left there for several days. The acclimatization process was completed by completely removing the lid. The lacquered objects were removed from the inner wooden crate and placed in their position inside the display case.
The entire process of climatic approximation took several weeks. Preparatory work, such as painting the inner display case surfaces in the desired color, the drying process, as well as the production and installation of display case bases, had already been completed by this time. This underlines the importance of a well-calculated schedule for the entire exhibition construction, which also involves other departments of the museum.
Following the object installation, the objects in the display cases were illuminated. In addition to fluctuating climate parameters, light is another important factor that needs to be controlled when exhibiting lacquered objects. Excessive and prolonged exposure to light can cause surfaces exposed to light to become matt and fade. Depending on which pigment was added to the lacquer for the purpose of coloring, a darkening effect of the surface can also occur.
So-called light damage can no longer be reversed and therefore always remains visible. They are particularly evident in direct contrast to surfaces that were covered by a closed lid, for example, and therefore not exposed to light. These surfaces retain their color and shine and are clearly distinguishable from the light-damaged area. The illuminance was controlled using a luxmeter and adapted to the sensitive painted objects.
In order to minimize exposure of the lacquer objects to light on the one hand, and to be able to present the lacquer collection to visitors on the other, the decision was made to install a motion detector that is activated when the visitor enters the lacquer cabinet, thereby switching on the object lighting. As soon as the motion detector no longer detects any movement within the cabinet, the lighting switches off again.
Once the object installation and illumination of the lacquered objects and display cases had been completed, the empty wooden crates were returned to their registered location in the depot. This means that each object can be assigned its individual wooden crate again when it is replaced.
The refurbishment of the lacquer cabinet is an example of the extensive knowledge conservators need to have about materials science, production techniques and scientific backgrounds in order to be able to carry out their everyday tasks responsibly and to the benefit of the objects.
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