Determination of weathering and conservation of sculptured stone by use of the laser method

摘要

Weathering and deterioration of sculptured stone and masonry is a natural process which stars at the same moment the stone is quarried and exposed to exogenous conditions. This process of natural decay has, however, been accelerated due to the emission of different man-made pollutants, domestic and industrial, local and global. The ISOLASER project is based on the laser microprobe technique for determining the depth of natural and induced weathering and the effect of conservation measures of cultural objects of carbonaceous sandstone and marble/limestone. The purpose of the project is to determine the depth of weathering and depth of penetration of conservation agents in unweathered calcite-cemented stone and the weathering profile in linseed oil-treated stone after accelerated weathering cycles in a climatic chamber. The analytical results show that even after such a short period as five weeks of exposure the effect of SO(sub 2), NO(sub 2) and elevated humidity on Gotland sandstone can be easily observed in a change of the (delta)(sup 13)C values in the outermost 2 mm of the stone. Treating the sample with linseed oil has a preserving effect on the rock and hinders the deteriorating effect of SO(sub 2) and NO(sub 2). The oil treatment even preserves the signature of previously incorporated organic carbon. Compilation of a questionnaire representing a broad field within natural sciences in cultural heritage research in Europe, shows an overwhelming positive approach to the project as such. The questioned researchers consider the laser method particularly useful as a complementary method in other investigations and states that the method can without doubt give new dimensions to the analysis of important cultural objects. 2 refs., 6 figs. (Atomindex citation 28:044646)