Cleaning Techniques in Conservation Practice review

This is a timely publication. Many of the contributors of the collection of papers giving guidelines as to current practice and some interesting case studies will be familiar to UK practitioners, but some will be unknown. This includes the American editors Deborah Slaton and Kyle Normandin.

Their introduction gives an overview of current orthodoxies with 'A Philosophy of Cleaning', via international practice from the USA, Canada and Australia and sets that in the context of the various Charters. The section on 'Goals and Approaches to Cleaning' is in my view exemplary and should be read by all commissioned to become involved with such works. Nicola Ashurst's introduction to the volume reminds readers of the cardinal rule that assumptions are never wise. She gives interesting details of petrographic analyses which she has commissioned over recent years to determine the nature of soiling, and the nature and condition of the stone substrate of particular buildings, and the inter-relationship between the two. The range of techniques commonly available has increased over recent years. It is salutary to remember that Nicola Ashurst's seminal two volumes on Cleaning Historic Buildings is now ten years old, and that the Historic Scotland's Stone Cleaning Guide for Practitioners is now twelve years old.

Of the case studies, that by Martin Stancliffe and the Doctors De Witte describing the cleaning of the interior of St Paul's is fascinating in itself, and in its description of the relatively new 'Arte Mundit' cleaning system eventually selected after some four years testing and consideration of the 'usual' traditional methods. The story, should, however be told as to how it came about that the circumstance arose, in the words of Martin Stancliffe: 'It was at this stage that discussions with Dr Eddie De Witte led to an evaluation of the recently formulated Arte Mundit process'!

The paper by Martin Cooper on the laser cleaning of sculpture, monuments and architectural detail finally explained to me how laser cleaning works, in a way which I can understand, which is an achievement itself. Of great interest is the description of case studies of the cleaning of exterior parts of buildings using the technique, both of exposed external sculpture, and the complete sandstone facade of the Rotterdam City Hall. The photographs of these works look absolutely striking. Sadly no details of the costs of these works are included, although it is stated that it might only be possible to clean two square metres per hour of a polluted sandstone surface, which might be only one tenth of the rate of cleaning using alternative 'traditional' techniques.

Other case studies are equally fascinating, ranging from paint systems on space rockets and a section on the hull of R.M.S. Titanic which has been recovered and is now exhibited, including the undamaged glass in three of the portholes! The detailed analysis of the sources of dirt in the huge St John the Divine Cathedral following a fire, so as to provide proof to insurers that the dirt was actually smoke and soot arising from a minor fire, rather than 'the patina of age' was carefully explained. Happily the right result was obtained! Similarly the attempts to improve the effects of the original construction defects on exposed in situ concrete at the Sydney Opera House has lessons for us all. Happily one of those involved in the original construction is still available to contribute to the design of the works of repair.

The only paper which disappointed me was that by Carlota Grossi and Peter Brimblecombe which describes the public participation exercises undertaken with visitors to the White Tower at the Tower of London. Which through questionnaires attempted to assess their perceptions and acceptability of the blackening of the building. The conclusion of the public response that 'it's not dirty; it's old' was probably inevitable in view of the questions asked of those visitors. Apparently the same questionnaires were used for similar research at Cathedrals through Europe. It might have been more interesting to compare the responses for those buildings.

The book is published as a special issue of the Journal of Architectural Conservation. The overview of the current typical techniques is exemplary. The book will be close to hand for the next cleaning project which comes my way.

Andrew D. W. Shepherd DipArch (Manc), DipCons (AA), RIBA, FRSA, IHBC

Architect and Year Master for The Architectural Association Post Graduate Building Conservation Course

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Donhead Publishing 2010