Camadas pictóricas na conservação-restauração do patrimônio cultural edificado: o uso de tintas modernas

Abstract

Paint is the most external component of most building's coating systems. It stands out as an indispensable finishing against degradation agents climatic, mechanical, pollutants and soluble salts. The paints are part of the painting system, being constituted by resin, solvent, additive and pigment. Resins name the paint and determine its main physical, chemical and mechanical characteristics; solvents are the volatile components that provide the application; pigments are solid particles that give color and provide covering power and additives improve specific characteristics of the formulation. The criteria for the conservation of the built cultural heritage are not well defined yet, mainly regarding the treatment of the pictorial coating layers. The objective of this dissertation is to enable in-depth knowledge of identification, characterization, documentation, and analysis of the resins that constitute these pictorial layers - focusing on its physical-chemical composition and compatibility, not just as an element of color. The core of this analysis are modern paints, applied as overcoating layers in the built cultural heritage. Modern paints derive from the development of new synthetic resins throughout the 20th century, namely: nitrocellulose resin and pyroxylin; alkyd resins; acrylic resins; chlorinated rubber; vinyl resins; polyurethane resins; silicone resins; epoxy resins and hydrocarbon resins. The paints derived from these resins are widely used by the market, but not always understood in their application singularities. This dissertation combines the bibliographic review of painting systems with the exams for characterizing the layers of pictorial coating in a case study. The analyzed case study is the building of the Secretaria de Viação e Obras Publicas from the city of Belo Horizonte (Minas Gerais) designed and built between 1895 and 1897 by the Comissão Construtora da Nova Capital (C.C.N.C). The method used comprises identification of the case study, field visits, sample collection, scientific documentation by image, conducting scientific examinations, documentary and bibliographic research. The results achieved confirm the prevalence of painting as a mere aesthetic component of the conservation processes of the built cultural heritage, unrelated to the specificities of its components. This work progresses in the constitution of modern paints, as well as their interaction on the existing substrate. Also, it certifies the need for collaboration among the different areas of knowledge, highlighting the preservation of cultural heritage as interdisciplinary.