Prékopa Ágnes (szerk.): Ars Decorativa 31. (Budapest, 2017)
Kornélia HAJTÓ: Restoration Options for Architectural Ceramics
Keim has developed a system of paints based on a calcium silicate binder with inorganic pigments. This sets up chemical bonds with the base, which also contains silicate components (rendering, ceramic, concrete or stone). Other paints have been developed with a two-component system (acryl polyurethane and epoxy) to provide durability against the weather. The pigments are bound in a layer of polymerized synthetic resin. The best means of achieving a match with glossy glazed surfaces is to use two- component varnishes such as IMPA 2K. These can also approach the original colour of the glaze through the incorporation of pigments into the varnish. Surface protection When building owners have exterior surfaces and architectural elements restored, they want the result to be as durable as possible. This demands protection against the threats posed by the weather and today’s atmospheric pollution. Since the presence of water and dampness accelerates nearly all the processes that lead to crumbling, disintegration and deterioration, an almost universal aim is to make the finished surfaces hydrophobic. Restoration product manufacturers such as Remmers offer products (Funcosil SNL) that can render treated surfaces completely water-repellent for some time. This also inhibits the deposition of atmospheric contaminants and makes the surface easier to clean. Funcosil is a solution of siloxane oligomer that permeates into the pores of the building element, where it reacts with atmospheric moisture to form polysiloxane. According to the data sheet, the active ingredient forms a macromolecular layer on the walls of capillaries and pores and does not obstruct the diffusion of water vapour. The surface thus retains its vapour permeability, allowing it to breathe, but does not absorb moisture from the external environment. Before applying a hydrophobic coating to the surface of a historic building, it is important to ascertain the absence of salt transport in the element and to eliminate 7. Fracture of roof ridge element along the nail used to fasten it 103
