A legacy of mistreatment: conceptualizing the decay of medieval sandstones in NE Ireland
Stephen Mccabe, Bernard J. Smith, Patricia A. Warke, 2010. "A legacy of mistreatment: conceptualizing the decay of medieval sandstones in NE Ireland", Natural Stone Resources for Historical Monuments, R Přikryl, Á Török
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Sandstone is commonly used as a building material in medieval monuments throughout NE Ireland. This paper explores the reasons why, and the ways in which, medieval sandstone monuments decay in the temperate Atlantic maritime environment of the north Antrim coast, using Bonamargy Friary, Ballycastle, as a case study. Monumental stone decay is placed in the context of inheritance and sensitivity to change, that is, the ability or inability of a sandstone to absorb change as a result of the past stress events it has experienced. A consideration of the combined impact of background environmental factors (such as salt accumulation, temperature cycles, frost, chemical alteration, soiling of the surface, changes in surface morphology and biological colonization) and ‘exceptional’ factors (such as lime rendering, fire, climate change, abandonment and conservation intervention) is used to formulate alternative decay pathways of the sandstones identified at the Friary. Discussion focuses on the value of identifying conceptual event sequences such as the cumulative impact of past events, individual and combined, to produce recognizable decay features seen in the present day. The possible impact of future climate change on the decay of medieval sandstone monuments is discussed.
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Natural stone is considered to be a versatile, durable and aesthetically pleasing building material. From the beginning of civilization, important structures and monuments have been built from, or based on, natural stone. Until the end of the nineteenth century, the use of local stone resources was mostly in balance with the local environment. Strict environmental legislation has resulted in the closing of many long-standing quarries in industrialized countries, which has led to a shortage of traditional stone varieties. This has caused problems for restoration practice. Cheap, imported stone from less industrialized countries has become more widely available in recent years.
Some of the issues related to built stone conservation and restoration covered by this volume are: the establishment of inventories of possible replacement stones; understanding the decay mechanism and use of preventive conservation methods for slowing down decay processes; evaluation of the properties of natural stone; and assessing the risks of using replacement stones of different qualities.