A sampling campaign was carried out in order to characterise decorative elements such as mortar, plaster and black coatings. The spaces sampled included internal and external spots, such as the Chapel of Our Lord in Gethsemane, the Porch, the Cells, the Cloister and the Church.
The characterisation of the material using x-ray diffraction, thermogravimetric analysis, a scanning electron microscope coupled with an energy dispersive x-ray detector and optical stereo microscope, was carried out at the HERCULES laboratory – University of Évora.
In terms of the mortars (internal and external), a calcareous whitewash was used as a binding agent. Like the mortars, the binding agent for the black coating is always calcitic in nature. Only two samples, recorded as exceptions, detected calcium and magnesium in the binder used in the Chapel of Our Lord in Gethsemane, revealing the likely use of dolomitic lime in this space, probably as a later intervention.
The black pigment was identified as being mainly vegetable charcoal. Analysis of the materials of the black coating did not indicate any type of functionality, certainly not of an insulating nature. However, its application, along with the volume and layout of the Convent, suggests an intention to imitate the surrounding landscape, recreating dark spaces similar to the natural cavities generated by the granite outcrops of the Sintra Hills.