Sustainable Preservation of Photographs in a Hot and Humid Climate: Dry Cabinets and Metal–Organic Framework Paper Composites

In a project to preserve photographic archives in Southeast Asia, the authors sought to develop sustainable solutions with low environmental impact, avoiding air conditioning and using locally available materials. Dry cabinets were tested and implemented to store a glass plate negative collection that was rehoused in envelopes and boxes made locally. The project took just over a year to complete, and two years of monitoring environmental conditions have shown that relative humidity can be stabilized at low levels. However, the dry cabinets are airtight to limit the introduction of moisture and dust, preventing air exchange. In order to avoid the build-up of degradation by-products released by the stored materials, and in particular off-gassing of acetic acid from the cellulose acetate-based photographs, the use of an adsorbent is necessary. To achieve this, a cellulose-based composite with particles of a porous hybrid inorganic/ organic solid, denoted as a metal–organic framework (MOF), at a very high loading over 70% by weight and shaped as a sheet of paper, has been prepared and tested. This special paper maintains acetic acid-free air in the cabinets and also helps to reduce the energy consumption by reducing the need for cool storage. This MOF paper composite traps small carboxylic acids and was found to be an appropriate solution for maintaining clean air in the dry cabinets or any other confined space or enclosure. Additionally, it can also be designed to trap other noxious pollutants such as hydrogen sulfide or formaldehyde, by choosing other MOFs.