This is the overarching question that HSLL researchers Jernej Markelj, Ida Kraševec and Matija Strlič, together with Josep Grau-Bove (Institute for Sustainable Heritage, University College London) and Evy Vereecken (KU Leuven and Royal Institute for Cultural Heritage), have investigated in a novel study published in the renowned journal npj Heritage Science under the title “A simple generalized mass transfer model for evaluation of the environmental performance of archival boxes”. The authors present a new approach to describing microenvironments in enclosures. Specifically, the researchers were concerned with prediction of the relative humidity damping capacity in boxes with different constructions and board types. By introducing a new “box preservation” index called the Humidity Attenuation (HA) index, the researchers were able to distil complex termohygrometric processes into a single value. The HA index describes the ability of enclosures to attenuate the relative humidity from outside. It ranges from 0 to 100, with lower numbers indicating a lower damping capacity and therefore poorer performance of the box. This numerical scale enables comparisons to be made between heterogeneous groups of boxes, such as ranking storage suitability of boxes made of cellulosic fibres (paper, corrugated and non-corrugated board, and textile), plastic boards, or coated with synthetic coatings. The results show that at low ventilation rates, moisture transport occurs mainly through the wall (except for plastic boxes – where the flow through holes and slits are important). The results also show that boxes filled with paper or stacked on top of each other buffer moisture better. The absorption and permeability part of the diffusion flow in boxes made from cellulosic fibres is quantitatively similar, but has an opposite effect in improving storage performance.

Researchers have also developed an online app (available at https://hsll.shinyapps.io/ha_index_pub/) that will hopefully help curators and conservators evaluate their own enclosures used in museums and thus support their decision-making for preventive conservation actions.

This work will provide a more realistic assessment of the suitability of museum enclosure microenvironments with respect to relative humidity moderation.

The article is available at: https://rdcu.be/ezAZb