NO STONE UNCLEANED Stonecleaning in Scotland Research Summary. Masonry Conservation Research Group, Robert Gordon Institute of Technology, 1992. 93pp, 36 plates, 11 figures, ISBN O 7480 0452 l. Price £8 (plus 80p p&p) from Faculty of Design, RGIT, Garthdee Road, Aberdeen AB9 2QB. Many historic stone buildings in Scotland have been cleaned in recent years but there is increasing concern that current cleaning methods may cause long-term harm. In 1988 Historic Scotland and Scottish Enterprise commissioned the Robert Gordon Institute of Technology to undertake a fundamental study of the nature of sandstone, its soiling and subsequent interaction with the various methods and materials used to clean it. Although it is based on Scottish experience, every Conservation Officer could read with this study with benefit. The report looked at the results of cleaning on 70 buildings throughout Scotland. Under laboratory conditions it compared the cleaning of soiled samples from 24 commonly used sandstones with samples of newly quarried material. Predictably, abrasive cleaning methods in the field and in the laboratory were both found to erode the face of the stone exposing other constituent minerals. The new roughened texture provided hospitable conditions for colonisation by new organisms. More surprisingly, the assumed benign chemical cleaners all had the same effect, dissolving not the dirt but the whole surface matrix of pollutant and stone. Invariably the acid or alkaline chemicals leached into the stone to a greater or lesser extent; their continuing reaction with the other mineral constituents and salts causing efflorescence or other chemical change. Where alkaline cleaner had not been properly flushed from mortar joints it attacked and broke down the pointing. None of the main techniques examined produced a uniformly satisfactory result - leaving surfaces with localised iron staining, pockets of persistent soiling below ledges, or evident physical damage. The technical shortcomings in each case were found to be accentuated by varying levels of operator CONTEXT 36 BOOKS competence and supervision and a lack of co-ordination where neighbouring buildings, especially in terraces, were being cleaned. The researchers found widespread political and public support for the value of cleaning in regenerating run-down areas and clearly expect the established momentum to continue. They conclude that planning authorities should formulate a policy framework both for standards of workmanship and to define overall objectives (eg total cleaning or removal of superficial deposits only), sometimes on a street-by-street basis. This is the weakest part of the report; m an area obviously fraught with technical difficulty local authorities need specific guidance 111 drawing up those new standards. This the consultants conspicuously fail to do; one cannot but question whether their real advice might well have been to call a moratorium on more widespread cleaning until its effects are better understood. Alan Taylor OTHERS PEOPLE'S DIRTYWASHING Stone Cleaning, and the nature, soiling and decay mechanisms of stone. Edited by R G M Webster, Donhead Publishing, 1992. 320pp, hardback ISBN I 873394 09 8. Price £30.00. Conference proceedings, by their nature, can often be something of a mixed bag. Some ideas only come alive or are only intelligible on the printed page; while others fail to inspire or illuminate without the presence of their authors or accompanying illustrations. For the reader, abstracts are clearly no substitute for being present in person. These proceedings were published ro coincide with an important international conference held in Edinburgh last April, sponsored by Heritage Scotland and Scottish Enterprise, and follows a 1988 initiative to fund research into the cleaning of sandstone by the Masonry Research Group at the Robert Gordon Institute of Technology in Aberdeen. The 31 papers are loosely grouped into six sessions covering the Broad issues; Case studies and experimental investigations; Cleaning of carbonate srone; Urban conservation issues; Chemical and microbiological studies; and Stone decay, weathering and future prospects. This gives an overall structure while allowing some selection by readers with only specialist interests. The introduction acknowledges that some overlap will be inevitable when the papers range from theoretical and philosophical concerns to practical case histories and laboratory experiments. The initial overview by lngvar Maxwell, Assistant Director of Works at Historic Scotland, begins the volume auspiciously. The rest of the contributors come from a wide variery of disciplines including social psychologists (on the public perceptions of soiled versus cleaned buildings), chemists and geologists as well as architects and planners. Conservation Officers will need to consider the relative value of specific papers to the size and cost of the volume as a whole before considering it a primary source for future reference. It is a pity that James Simpson's views on cleaning and the paper on graffiti removal by Burlin, Russell and McCaig only appear as brief abstracts given their direct relevance to most Conservation Officers' day-to-day work. It is becoming increasingly important that Conservation Officers become familiar, at least in outline, with the findings of the considerable body of current research. That being done on sandstones will be of widespread interest because the stone is so often used. While it is doubtful if any but the most important buildings will be subject to the kind of detailed chemical analysis presented here (for example on statues in Padova, Italy), lessons can be learned which will be of wider application. Donhead is to be congratulated for publishing the proceedings so quickly. It has been printed using the camera ready copy provided by the editors and contributors but this has not detracted noticeably from the presentation. Bob Kindred CONSERVATION AT LARGE Managing World Heritage Sites in Britain. Edited by Peter Burman, Jane Fawcett, Sir Bernard Feilden & Lord Kennet. 1992. 140pp. A4, spiralbound. ISBN 0 9517677 3 9. Available from ICOMOS UK, 10 Barley Mow Passage, London W4 4PH. Price £16.95 inc p&p (£14.95 to !COM OS UK members). Unless intelligent life is found in inter-stellar space, it is likely that World Heritage Sites will remain the ultimate expression of the cul rural heri rage in its architectural and archaeological form. The qualities of World Heritage Sites and the rigorous processes by which they are selected help establish a standard by which national and local standards may also be judged. The Proceedings of this symposium, held in York in November 1991, are therefore of more than passing general interest. . In introducing the background to the "1972 UNESCO Convention concerning the Protection of the World Cultural & Natural Heritage" Dr Lynde! Prott of the Physical Heritage Division of UNESCO remarked that the number of national signatories had risen to 118, making it one of the most successful international conventions; an especially significant figure when it is remembered that cultural matters are not always a high priority for governments. The development of a coherent philosophy has preoccupied the World Heritage Committee in the succeeding 19 years. The best known product of its deliberations has been the World Heritage List and despite the lengthy procedure for vetting applications (taking up to 15 months), 45 submissions were made in I991. In simple terms, nominated sites should represent a unique artistic achievement, a masterpiece of the creative genius; or have been of great cultural influence over time or over a wide area; or bear a unique or at least exceptional testimony to a civilisation which has disappeared; or be an outstanding example of a traditional human settlement (especially in the face of irreversible change); or associated with events, ideas or beliefs. Further criteria require authenticity and integrity in design, materials, workmanship or setting. These rules, Dr Prott pointed out, "prove inconvenient to those who believe that reconstruction ro portray the past is more attractive to routists than leaving the original intact". 43
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