DELAYING THE INEVITABLE: PROTECTIVE TREATMENTS FOR ARCHITECTURAL STONE

As long as there have been stone buildings and monuments, there has been a desire to conserve these structures. Since the industrial revolution, this desire has led to the testing, patenting and applying of protective agents to reduce the rate of deterioration. These protective agents have been in the form of barriers, water repellents and stone consolidants. They typically have been applied to sandstones, limestones and marbles. Often seen as a panacea for all stone deterioration, some treatments have accelerated deterioration of the monument, and some may have reduced the rate of deterioration. The appropriate selection of stone protective treatments requires a thorough understanding of the stone and exposure, and relies on the interdisciplinary work of conservators, petrographers, and chemists. The presentation will begin with a historic look at early patents for protecting stone monuments, the evolution of the treatments, laboratory and field methods used to access their efficacy and examples of installation. Recent case studies of significant monumental structures which have included laboratory evaluation of the stones as well as the protective treatments are reviewed.