The conditions survey and materials analysis identified several types of decay mechanisms and their causes, both to be addressed during the course of emergency stabilization. Detachment of the enfoscado from the masonry dome and walls and delamination of the enlucido from the enfoscado were the most serious forms of deterioration recorded. Detachment and delamination destabilize the painting's support and are due to years of moisture intrusion through the dome and roof from the installation of later membrane roofs. Blind detachment, detected audibly by tapping the surface of the plaster, was especially problematic due to the immediate and rapid collapse that can occur without visible warning. While detached voids were large enough to accept a lime-based grout, areas of thin delamination instead required the injection of a filled acrylic emulsion adhesive for reattachment. Areas of severe delamination between later painting campaigns required temporary tissue facings to stabilize these painting fragments before plaster stabilization could proceed. After emergency stabilization in 2006, the decision was made to focus on conservation and restoration of the earliest (17th century) paintings. A number of techniques for removal of later limewash layers were tested, including dry mechanical, chemical and mechanical, and strappo techniques. Strappo techniques, using colletta or hide glue with either gauze or muslin, were also tested for the possible removal and display of fragmented vignettes from later campaigns.

 

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