Chapel of Bones in Évora (Portugal): Study of the plasters characteristics and state of conservation.

Abstract

The Chapel of Bones, which belongs to S. Francisco Church, probably dated from the end of the sixteenth century is one of the best known monuments in Évora – Portugal. This Chapel is very special because all plasters are composed by human bones agglomerated with a lime based mortar. The plasters and setting mortar, by their antiquity, durability, compositions and application techniques, have themselves a considerable historical value. Due to detachment of the plasters from the internal surface of the chapel walls, an intervention aiming at their restoration was planned. Samples of the plasters were extracted and laboratory tests were carried out. In this article, the main results obtained in the physicochemical characterization of the mortars from Chapel of Bones are presented; the diagnosis methodology applied for the evaluation of the state of conservation of the plasters is described and the recommendations made for the repair mortars are briefly referred. The results obtained indicate that the mortars are generally in good condition and the defects are mainly related with the bones alteration. The compositions of mortars are very distinct: the plasters are composed by dolomitic air lime with siliceous aggregates and the setting mortars are earth-based.