Acceptable temperatures for storing collections in a working environment range from 65-70° Farenheit with levels of relative humidity in the range of 45-50%. These conditions can be most evenly maintained in inside rooms, away from heat sources such as heating pipes and radiators, windows and exterior walls. Monitoring conditions in your storage areas in a systematic manner over time will give you insight into how well your building adjusts to seasonal climatic conditions and can highlight problem areas. This is best monitored with the use of a recording hygrothermograph. Some options in hygrothermographs include: pen & ink graphing; built-in or portable digital meters that output to computer software; electronic instant readout type available from a household electronics store. Your physical plant manager may also be able to provide you with data regarding your rooms' air handling systems and point out solutions for problem areas.
Drier conditions will reduce the flexibility of materials resulting in: difficulty opening books and and unrolling papers; shrinkage and separation of adhered materials; increased cracking of brittle paper, wood, and paint. More humid conditions will increase the potential for mold outbreaks and increase the rate of acid hydrolysis of paper and plastics. Be aware that photographic materials benefit from cooler, drier conditions than exist in a working environment. If the photographic or other collections are not accessed often, consider creating or sharing in an alternate storage space where the temperatures can be held at lower temperatures and relative humidity and more tightly controlled. Materials which are accessed from cold storage should be allowed to come to equilibrium with the climate of the working environment before they are used.
