Application of pH sensors for preventive preservation in storerooms at the Museo Nacional de Ciencias Naturales (Madrid)

Environmental monitoring is essential for the proper preservation of natural materials in museums, both in exhibition halls and storerooms. Deterioration and degradation of natural materials occur when deviations from neutral pH conditions take place as a consequence of pollution, visitors, non-professional interventions, unsuitable storage conditions, catastrophes, or vandalism. Simple techniques to measure the extent of acidic or alkaline gasses in the museum atmosphere are therefore important, especially in storerooms where objects are placed for long periods. Sol-gel pH sensors have been synthesized and applied for monitoring storerooms of the Museo Nacional de Ciencias Naturales of Madrid (Spain). pH monitoring was carried out for one year under different meteorological seasons. Most of the storage systems monitored maintained a neutral pH, while some of them were slightly acidic. These acidic conditions could favour chemical deterioration on organic structures of naturalized animals, and cause acidic corrosion in minerals and inorganic parts of the objects.