After completion of conservation treatment in 2005, the Getty Conservation Institute and the Dunhuang Academy began discussions on presentation and interpretation of the cave to the public and an appropriate visitation policy.

A viewing platform inside a cave filled with detailed wall paintings

The raised platform with lighting and interpretive panels in the cave. © Dunhuang Academy

Lighting

In consultation with lighting engineers in the United States and China, the project team developed and installed lighting for the cave. The final installation comprised several low-voltage LED sources to illuminate the walls and ceiling of the main chamber. Simultaneous research was undertaken on the light sensitivity of colorants present in the cave, along with long-term monitoring of the stability of the wall painting pigments and colorants using International Organization for Standardization (ISO) blue scales textile fading cards and a lux data logger. This research impacted decisions on safe and acceptable light levels in other caves at the site.

Platform Concept and Design

Existing physical barriers to prevent visitors from touching the paintings consisted of heavy glass screens in aluminum framing with wheeled bases. Cave 85 has a large floor area, which enabled a different solution: a viewing platform that would raise the visitor above the floor level. The optimal height of the platform was determined to be 1.3 meters above floor level. This results in a loss of much of the lower painting register yet allows for the statuary group to be seen unimpeded from the doorway and corridor. The steel structure of the platform and its steps rests on the cave floor; the surface is carpeted wood. The railings, which incorporate a tempered glass panel, define a platform space of 7.18 by 4.88 meters. The platform also serves to carry the LED lighting system and interpretive panels, which were mounted in the four corners.

Interpretation

Multiple objectives may be served by opening the cave to visitors. Foremost was the desire of the Dunhuang Academy to convey a conservation message, detailing what goes into the work by creating a special experience. Visitors to the site generally recognize the fragility of the art, with an awareness of the impacts of burgeoning tourism in China to cultural sites, but they have only a rudimentary understanding of deterioration processes and their mitigation by a systematic conservation, management, and monitoring program.

Panels

To this end, five interpretive panels were created for the cave: four on the platform and one in the entry corridor. They focus on conservation issues and therefore supplement the Dunhuang Academy guides’ regular tours, which are principally related to history and iconography (although the guides are increasingly being provided with conservation information to incorporate into their tours). The guides were asked for input on both content and location of the panels.

Visitation Management

The results of a multiyear study by the two institutions on establishing a sustainable visitor carrying capacity for the Mogao Grottoes served as the basis for the visitor policy for Cave 85. Restricted visiting conditions were established including: carbon dioxide levels not to exceed 1,500 ppm (which relates to visitor comfort, health and safety) and RH not to exceed 62% (applicable to caves at risk from salt-induced deterioration). RH is influenced mainly by intrusion of outside air through open doors and not by visitors’ exhalations. Thus, during high humidity Cave 85 must remain closed to visitors. Humidity control through management practices is essential for safe and sustainable visitation of the cave.

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