Covering paintings with protective materials : an evaluation of backing, glazing and total enclosure practices with particular reference to the Maltese context

Abstract

Cultural material can be preserved only if maintained in adequate environments. This dissertation presents possible solutions to how the relative humidity (RH) and temperature of exhibited canvas paintings can be stabilised and retained within the recommended values in order to limit conservation problems such as cracking and detachment of the paint layer from the canvas support. The stability of the RH and temperature inside the museum can be improved by several passive and active means. However, such stability is often challenging, especially if the museum is limited in resources or if the building itself can not sufficiently shelter its interior from the external climatic conditions. When there are such limitations in stabilising the RH and temperature of the entire museum space, there is the possibility of covermg paintings with protective materials to improve the paintings' microenvironment. This dissertation explains how the protective-covering practice can improve the paintings' microenvironment and explores both the advantages and limitations of different protective-covering systems. The author tested a dummy canvas painting covered with backing and glazing materials inside a typical Maltese exhibiting environment, featuring unstable RH and temperature values. It was observed that the daily RH fluctuations of the exhibiting environment were considerably stabilised inside the protective-covering system. However, the RH of the covered painting was still influenced by the museum's seasonal RH fluctuations. As a consequence, the RH of the covered painting gradually rose above 65% and was stabilised at such a high value for almost three consecutive months, possibly posing the covered painting to biodeterioration risks.