7. Stone Conservation

Since antiquity, replacement and repair of damaged stone has been practised to delay the deterioration of buildings and monuments. Today, the aim of stone conservation is the preservation of these historic and/or artistic objects for future generations in the state in which we have received them. The approach that has been taken to address this challenge has direct links to the emergence of chemistry in the 19th century. Chemicals such as water glass, fluorosilicates and ethyl silicate were tested as consolidants for stone shortly after their synthesis in the laboratory. After World War II, organic compounds, such as acrylic and epoxi resins found their way into conservation practice. This chapter deals with all the steps required in a conservation intervention, such as the problems presented by cleaning as well as those of desalination. It includes a review of conservation materials, such as consolidants, water repellents and biocides. Silicon organic compounds are given special attention since they are the main chemicals used in the formulation of both consolidants and water repellents. The requirements for the various mortars that may be needed, including renders, as well as that of other finishes such as paints and antigraffiti coatings are also discussed.