ABSTRACT

The prehistoric rock art and its surroundings consist of an important heritage to be registered, studied and preserved. This research is fruit from the necessity to amplify the knowledge above the paintings composition, with the objective to realize, with maximum security, preservation interventions. This doctoral thesis collects the results obtained by an experimental study devoted to characterize the physical-chemical behavior of a few organic substances, probably used by prehistoric humans, as binders on the rock paintings and the behavior of fixative products applied in the conservation. For the realization of the assays paintings simulations have been prepared with five pigments (red and yellow from iron oxide, white from kaolin, black from manganese oxide and charcoal from wood) and eleven naturals organic substances (jatob‡ and pine resin, pequi and baba¨u oil, copa’ba balsam, gum arabic, pork fat, blood, urine, egg and water), and dried pigments. The dyes prepared with these products were applied on the limestone specimens. Four paints fixatives were also assayed: Paraloid B72, Primal AC33, Estel 1000 and lime water. The simulations have been observed to determine the variations of structure, morphology, color, adherence to the rock substrate and the resistance, before and after the accelerated ageing assays (UV radiation, temperature and humidity, and saturated atmosphere with SO2). Analyses were concluded by FTIR, Py-GC/MS, SEM/EDX, VMP, Visible Spectrophotometry, Micro-chemical Analyses and Optic Microscopy. The results obtained in the experiments of lab have been compared with real samples, extracted from the rock paintings of the Parque Nacional Cavernas do Perua¨u, Minas Gerais, Brazil, and make evident the presence of organic materials from animal source used at the dyes composition. In relation to fixative product the Paraloid B72, presented good results concerning the application, fixation the paint layer and stability thorough to the accelerate ageing.