The Maya site of Calakmul: “in situ” preservation of wall paintings and limestone by using nanotechnologies

Mexican cultural heritage, one of the richest in the world, is an essential source of iconographic and historical information about Mesoamerican civilizations. The influence of European schools of conservation is undeniable in the formation of Mexican conservation, which ‘imported’ most of the European conventional technologies, such as acrylic and vinyl polymers as organic consolidants, for the conservators of cultural heritage. Unfortunately, the unfavourable Mexican climate increased the rates of polymer degradation, and dramatic degradation effects, such as the severe flaking of surfaces and paint detachment, became apparent in a very short time. One possible conservation option used by some Mexican conservators was detachment of the paintings. A different approach, the subject of this contribution, is the use, instead of polymers, of physico-chemically compatible materials for conservation treatments, which ensure durable results. The paper highlights innovative methods based on nanotechnologies that have been tested for the in situ consolidation of paintings and limestone in La Antigua Ciudad Maya de Calakmul in Campeche, Mexico, designated a United Nations Educational, Scientific and Cultural Organisation (UNESCO) World Heritage Site since 2002.