STONE WEATHERING AND DECAY

The ICOMOS-ISCS Illustrated glossary on stone deterioration patterns

Glossaire illustré sur les formes d’altération de la Pierre”  2008

This is a welcome international addition to the current cascade of books and other publications concerned with weathering and stone decay. The atlas, which is comprehensive and attractively produced, is also available as a free download from the website and should, as its preface states, go a considerable way towards the setting up of a common language amongst those interested in describing stone decay patterns and  in communicating them to co-workers in the field of stone conservation and repair. 

Describing stone decay patterns has always been bedevilled by the subjective rather than objective description of stone decay patterns and an easily accessible, well illustrated atlas of the major features, following on from the work of Bernd Fitzner and co-workers at Aachen University, was long overdue.

At the risk of being considered overcritical about a publication which is of high quality and well worth using, I would suggest that perhaps in any future edition a number of useful additions could be made. As one of the major conservation concerns at present is how buildings and monuments will be affected by climate change, it is perhaps surprising how little information, except what can be gleaned from the images and their captions, is given regarding the climatic setting of the stone decay patterns observed – tropical, temperate, desert etc. 

Also the locality of the stone would have been useful  - inner city, rural or isolated monument etc, as well as perhaps the age of the building or monument as an aid to determining over what period of time a particular stone decay pattern might have developed: did it take 2, 20, 200 or 2000 years to develop. 

As a geologist I would also have preferred a little more detailed information on the lithologies of the stones illustrated. The different stone types covered are simply described, with occasional rare exceptions, as sandstone, limestone, marble, granite etc. It would have been useful to know whether some of the decay characteristics illustrated can be related to either mineralogical composition and / or geological age.

Geoscientists, chemists and conservationists continue to study stone weathering and decay with an ever increasing armoury of new, advanced technologies without as yet it seems coming up with definitive answers for many aspects of the problem. 

This new ICOMOS atlas at least holds up the promise that the descriptive language used to communicate this work has now been rationalised and might therefore lead to more breakthroughs in the understanding and ultimately the control of the decay of our stone heritage.

Graham Lott 2009