Performance and Durability of Paints for the Conservation of Historic Façades

Abstract

This paper analyzes the performance of various types of paints available in the Brazilian market, including PVA, matte acrylic, silicate, and lime paints within the context of their applicability to the conservation of historic building facades. Considering distinct suppliers and application methods, this study highlights the importance of tailoring paint selection to the preservation requirements of historic edifices, taking into account local preservation norms and the material characteristics of the buildings’ original construction. The paints were evaluated based on water vapor permeability, washability, and adhesion. Furthermore, the paints’ color variation with exposure to accelerated artificial aging was assessed. For testing purposes, specimens produced from cellular concrete slabs were used as substrates, which were coated with the paints under study. Based on the results, it was observed that, regarding the diffusion of water vapor, the silicate and lime paints presented the highest permeability values, and the acrylic and PVA paints had the lowest. Concerning washability, the silicate and lime paints showed the greatest wear. The adhesion tests revealed that, except for lime paint, detachment often occurred at the substrate. As for the accelerated aging test, lime paint exhibited the most significant color variation, losing its pigmentation considerably over time. With the results of this research and considering the main preservation requirements of historic coatings, silicate-based paints may be considered the most suitable.

Aging of a Poly(vinyl acetate)-Based White Glue and Its Durability in Contemporary Artworks

“…More recently, the assessment of the conservation conditions of design objects made of extruded PVAC-based resin filaments and exposed to decades of natural aging showed the formation of aromatic and unsaturated fluorophores [ 11 ], related to the presence of plasticizer and the extensive deacetylation of the bulk polymer, respectively. Many studies also concerned the degradability of vinyl acetate-based adhesive used in works of art, for canvas lining, and other conservation practice applications such as consolidation of wall painting, wood, glass, paper, or metal [ 12 , 13 , 14 , 15 , 16 ] In general, the copolymeric nature of the main component in most commercial adhesives, e.g., copolymer of ethylene, (meth)acrylates, or other esters with vinyl acetate, does not modify the process of degradation, eventually accelerating its effects [ 12 ]. The main degradation route is still characterized by the loss of acetyl groups, while the less extended processes resulting from the competition between depolymerization and cross-linking have the effect of strongly affecting the adhesive solubility and removability.…”