An Insight into the Limits and Possibilities of the Biological, Chemical, and Mechanical Performance of GluePaste Lined Paintings

Glue paste has been the most widely used lining adhesive in the Southern European tradition. This research was devoted to studying the mechanical performance and failure mechanisms of mock-up linings made with selected simplified glue-paste recipes when subjected to changing environments as a function of the materials and application techniques used. For this purpose, different qualities of wheat and rye flours were tested, mixed with selected animal glues in different proportions. The elimination of additives from the recipes studied provided coherence and clearer evaluation of results. Two representative lining canvases were selected, and linings were carried out following the Italian tradition. The lined mock-ups were subjected to RH cycles, and the impact on the mechanical, chemical, and biological properties of the lined paintings was reported, with special attention given to the effects of the degree of milling, the cereal protein content of the flours, and the weave density of the lining fabrics.