Mission Statement

The aim of the Scottish Stone Liaison Group is to enhance availability, promote utilisation and advance knowledge and skills in design, specification and use of indigenous Scottish stone in existing and new build projects.


Natural Stone Institute

Issue No. 5 Summer 2003

Improving materials testing and technical information in the UK roofing slate industry

The University of Paisley has been successful in the Department of Trade and Industry’s 2002 Partners in Industry (PII) Open Competition. The partners in the project are University of Paisley, Scottish Stone Liaison Group, Historic Scotland, Terry Hughes, Slate Consultant, University of Dundee, Alfred McAlpine Slate Ltd, Burlington (Slate) and The Delabole Slate Company. The project is planned to start in September 2003 and will run for two years.

The aim of the research is to improve the prospects and competitive position of the UK roofing slate industry by the development and adoption of innovative methods of materials assessment for new and recycled roofing slates. This will demonstrate the quality and longevity of UK slate in comparison with imported slate in both new building applications and built-heritage conservation.

The project will build on the work which has been carried out at the University of Paisley on the weathering of slates. This research started in 1995 when Historic Scotland commissioned Dr Joan Walsh, then at the University of Glasgow, to assess the resources of Scottish slate. In order to assess the properties of Scottish slate it was necessary to compare them with those of fresh slates from producing quarries. As there were no producing quarries in Scotland, these were obtained from elsewhere in the U.K. as well as imported material. An important aspect of the research was assessing the useful life of the slates. The limitations of the different national standards for testing slates for durability were recognised, and alternative testing methods were developed. These tests provided a procedure for assessing the relative durability of different slates, both local and imported, making it possible to demonstrate scientifically the longevity of British slates when compared with imported alternatives.

As the name suggests, a key feature of the PII scheme is partnership with industry. All the principal UK slate producing companies; McAlpines, Burlington and Delabole, are supporting the project by supplying slates for testing, by providing data on the results of tests by traditional methods and information on performance under natural weathering conditions. Historic Scotland, who have initiated and supported the research from the beginning, will provide data on the performance of slates on historic buildings. The University of Dundee will provide expertise on the supply and demand for slates, while the Scottish Stone Liaison Group will be actively involved in the dissemination of results.

The project will be a run by a steering committee which will include Terry Hughes, Slate consultant, and representatives of the University of Paisley, Scottish Stone Liaison Group, Historic Scotland, the University of Dundee and the Burlington (Slate) company.

One beneficial outcome of the project will be the funding of a weathering chamber, which will allow the experimental weathering of slates. The University of Paisley is often commissioned to assess the durability of slates intended for use on historic buildings and in conservation areas. In addition, fresh samples have recently been obtained of slate from the Ballachulish area and Macduff slate from the Hill of Foudland. Testing the slates for durability involves subjecting them to lengthy experimental weathering regimes, which will be considerably accelerated by the use of an automatic weathering chamber, enabling results to be obtained in a shorter time frame.

Dr Joan Walsh