Author(s)

P. Stepien, R. Kozlowski & M. Tokarz

Abstract

Gypstop - colloidal silica for protective coating of porous building materials: practical experience at the Wawel Castle, Cracow, Poland P. Stepien," R. Kozlowski^ M. Tokarz^ ^ RK Developments, 30015 Cracow, Poland * Eka Nobel AB, 445 80 Bohus, Sweden ABSTRACT The GypStop process involves the impregnation of porous building materials with water based silica materials to produce a protective layer of silica inside the pore system of the treated material. During the last two years the method has been employed in practical conservation projects on porous limestone and plaster at the Wawel Castle, Cracow, Poland. Our observations have shown that GypStop is very effective in protecting carbonatic porous materials against corrosion from acidic air pollutants. It also considerably reduces deposition of dirt and dust. The GypStop products were also successfully used to produce thin semi-transparent coatings on the surface of the stone or plaster. The GypStop treatment was effec

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