Environmental evaluation of the holdings at the CCHS-CSIC Tomás Navarro Tomás Library

Abstract

The most innovative procedure for preventive conservation of library holdings, especially those of historical interest, lies in the evaluation of environmental parameters witch have a negative effect on the conservation of such materials. The application of sensors permits for full, accurate and secure monitoring of environmental conditions and allows for the prediction of chemical-physical mechanisms of degradation, as well as of the most suitable procedures for controlling them. The sensors used in the present study were prepared by the sol-gel method and change colour when variations in the evaluated parameters occur. All of the sensors are reversible, reusable and can be regenerated. Temperature, relative humidity, illumination and acidity were the parameters evaluated. In the first stage, conventional apparatus were used to determine the critical ranges of variation for such parameters. Subsequently optical sensors sensitive in such ranges were designed and prepared. These sensors were calibrated and distributed throughout the rooms containing the holdings (approximately 3.200 square meters). The optical response of the sensors (change of colour) was recorded by visible spectrophotometry during the spring and summer of 2009. The use of sensors has the following advantages: low cost, no need for wires or apparatus during exposure, small size, reversibility, and short response time. The resulting data have revealed the environmental conditions of the conservation of the holdings, including environmental acidity, a parameter that could not be evaluated previously through conventional procedures.