Lecce stone belongs to the group of Miocene limestone and is distributed in many areas of
the Salento peninsula. The great part of the historical buildings, both religious and civil, in
this area have been constructed with this porous and soft material.
In the past, various methods and recipes have been used to protect the surfaces and ensure
their longevity. However, these ancient "recipes" are unidentified, because these techniques
were known only by the artisans who used them [2].
For this purpose, selected religious and civil buildings in the territory of the province of
Lecce, made of Lecce stone, not yet restored and possibly treated with some of these
unknown recipes because of their good conservation state, were studied and the presence
of surface treatments was investigated.
Samples were analysed by Py/GC-MS with and without thermally assisted hydrolysis and
methylation using tetramethylammonium hydroxide (TMAH). The results of the analyses
showed that these buildings have been protected with different natural products. Moreover,
for the first time, chemical biomarkers demonstrating the use of prickly pear leaves (Opuntia
ficus indica [3]) as protective surface finishes have been identified
