Aspects of weathering, that is, physical and chemical changes in stone, are briefly noted in this work. Weathering of building stone is complex. The body of literature on this topic has increased greatly in recent years, and the field is not without controversy. With a few exceptions, for example Mostafavi and Leatherbarrow (1993), the role of weathering in the enhancement of a stone structure has not been appreciated. In the past, and still today, many sacred structures have been needlessly subjected to harsh cleaning methods, including sandblasting. A dark patina on silica-cemented sandstones, for instance, adds to the historic look of structures, does not seem to do them any harm, and could conceivably act to protect their exteriors. Many sandstone churches in the Cleveland area were cleaned in the 1980s and 1990s, most notably the Old Stone Church in downtown Cleveland. A dark patina on some other rock types, especially limestones and marbles, however, often is indicative of problem areas that should be attended to.

Go to: next section / previous section /main index