Monitoring the Dracula exhibition space with HOBO data loggers

Stoker's notes, including chapter outlines, character lists and documentation of his research and reading about vampires and other demons, are the inspiration for the museum's "Dracula and Friends" exhibit, which runs from late September through early November as part of the museum's annual Dracula Festival.

Kathy Haas, assistant curator at the Rosenbach, explains that to avoid the risk of damage and to best preserve Stoker's notes and all of the Rosenbach's rare books, manuscripts and objects, the museum must maintain specific humidity, temperature and light levels. She explains, "Because our objects are delicate, we try to keep things as stable as possible," and the museum typically limits the duration of exhibitions to four months to avoid excessive light exposure.

To expertly monitor the indoor environment, the museum's curators install HOBO data loggers in each exhibition gallery, storage room and occasionally in display cases that contain objects on loan. Data loggers are also placed in shipping crates for loaned objects to ensure that temperature and humidity levels remain stable during transportation. Because these devices are small and portable, the HOBO loggers can be placed unobtrusively without interfering with the visitor experience.

Haas notes that with "thousands of books and manuscripts on paper", the relative humidity level at the Rosenbach is of great importance. If the humidity is too high, paper can absorb moisture, mold can develop and book bindings can warp.

To avoid these potential problems, HOBO data loggers are used to measure and record the relative humidity every ten minutes. The goal is to maintain around 50% RH, and if conditions deviate too much, staff take action to correct the environment. Curators also track humidity levels over time to identify long-term fluctuations in humidity, which can also damage museum exhibits.

Temperature can also significantly affect museum exhibits. Temperature changes can cause pieces to expand and contract and become damaged; warm temperatures also accelerate the chemical processes of deterioration. Haas notes that "what is ideal for objects is not always ideal for people," and therefore they must balance the comfort of visitors with the temperatures that the museum exhibits and furniture require.

Because the two buildings that house the Rosenbach Museum & Library are historic, maintaining the required environmental conditions can be a challenge. Fortunately, by using HOBO data loggers to monitor these conditions, museum staff can make the necessary changes to correct or mitigate conditions that fall outside of the acceptable range. Additionally, the Rosenbach uses its temperature and humidity data when completing standardized facility report forms that all museums require prior to approving loans. Some of the data loggers are also equipped with light intensity sensors so that the Rosenbach's curators can ensure that sensitive objects are not exposed to more light than is recommended.

With precise monitoring of humidity, temperature and light intensity by HOBO data loggers and the Rosenbach Museum & Library staff, all of its rare treasures, including the working notes for "Dracula," should be well preserved for years to come.

Thanks to the precise monitoring of humidity, temperature and light intensity by the HOBO data loggers and the Rosenbach Museum & Library staff, all of its rare treasures, including the working notes for Dracula, should be well preserved well into the future.