Scottish slate was historically produced from four areas across the country: Ballachulish, Easdale, Highland Border and Macduff. Its unique and distinctive appearance is a direct consequence of its geological characteristics. Most important of these is slatey cleavage which determines how easily and how finely the material can be split. Because of its generally poorly defined slatey cleavage, Scottish slate is not capable of being split into the smooth, regular, finish of slates sourced from elsewhere. This feature was turned to economic advantage by the slate workers as they cut roofing slates from quarry blocks to whatever size could be produced, and laid the resulting variable sizes of slate in diminishing courses on the roof. Scottish roofscapes thus reflect the variety in the visual and performance characteristics of Scottish slate sourced from the four producing areas, and from different quarries within the areas. However, the last comprehensive survey of the quarry sources for Scottish slate was "Wartime Pamphlet 40: Scottish Slates", published in 1944. The Scottish slate industry was in decline at the time this survey was carried out, and since the mid-1950s quarrying for slate has ceased entirely in Scotland.

Scottish slate roofs are a distinctive element of many buildings of traditional construction built until the early years of this century. and therefore make an important contribution to the integrity of the built environment. While Scottish slate is particularly well suited for use as a roofing material in Scotland and is of proven durability, some maintenance is required. involving tasks such as the replacement of lost or broken single slates or the re-roofing of a nail-sick roof. These repairs generate a demand for matching Scottish slate, a demand which must currently be met by recycled slate as newly-quarried slate is not available. This is an unsustainable situation, and erosion of the quality of Scotland’s roofscapes is resulting.

Recognising the need to revive the Scottish slate industry, in 1995. Historic Scotland commissioned the University of Dundee to study the factors affecting the demand for Scottish slate. This research has now been completed and has been published as Scottish slate: The potential for use in building repair and conservation area enhancement" Research Report. Also in 1995, University of Glasgow were commissioned to investigate the performance of Scottish slate from all the quarries listed in Pamphlet 40 for use as roofing slate and select those quarries that, from a geological point of view, are most suitable for re-opening. This work has been published in two volumes: a Research Report entitled "Methods of evaluating Slate and their application to the Scottish slate quarries" and this Technical Advice Note.

Historic Scotland has also been fortunate to be able to publish Gerald Emerton’s Research Report "The Pattern of Scottish Roofing". This report builds upon Mr Emnerton’s years of experience and his unique photographic archive of traditional roofs in Scotland Sandstone. schist and true slate. pantile and other man made roofing materials are all described in detail, as are the traditional techniques for their fixing on the roof. Released in conjunction with the Glasgow and Dundee studies, this volume ably complements them by illustrating the striking visual distinctiveness of traditional Scottish roofs.

This Technical Advice Note provides a comprehensive directory of the visual and performance characteristics of slate from all the quarries described in "Wartime Pamphlet 40". Its publication will therefore facilitate the choice of appropriate materials for the repair of listed buildings, a condition applied to the receipt of grant aid for repairs to listed buildings by the Historic Buildings Council for Scotland (HBC) since 1953. However, as newly-quarried slate is not available, all matching Scottish slate currently used to repair historic buildings has been salvaged from other traditional buildings built pre-1950. To 5uppOrt the appropriate repair of Scottish historic buildings. the HBC has called for Scottish slate to be brought back into production. This TAN also serves as an initial scoping study for those in the stone industry who have expressed an interest in re-opening slate quarries in Scotland.

Inevitably, related issues have moved on since these research projects were commissioned. In particular. in May 2000, Rhona Brankin MSP, the Deputy Minister for Culture and Sport, launched the Scottish Stone Liaison Group (SSLG). Membership of the group includes the Stone Federation GB, the British Geological Survey, the National Federation of Roofing Contractors, the Scottish Building Employers Federation. Scottish Environmental Protection Agency, the Royal Incorporation of Architects in Scotland and the Royal Institution of Chartered Surveyors in Scotland amongst others. This group was established to provide an appropriate industry-wide forum, to bring together all those with an interest in reviving the Scottish stone industry. One of its specific aims is:

‘To address the question of the availability of indigenous materials (stone and slate) required jor the maintenance of our built heritage ...‘'

This TAN, coupled with the related research reports from Glasgow and Dundee Universities and that of Gerald Emerton, will provide valuable data and evidence to assist in resolving this situation.

INGVAL MAXWELL Director, TCRE