BCD 2017

T H E B U I L D I N G C O N S E R VAT I O N D I R E C T O R Y 2 0 1 7 91 MASONRY 3.2 • Historic & Listed Building Repair • Accredited Conservation • Award Winning Traditional Plasterwork SKILLINGTONS SKILLINGTON WORKSHOP LTD. TEL: +44 (0)1476 565671 WWW.SKILLINGTONS.CO.UK FIND US ON FACEBOOK Facebook “f” Logo CMYK / .ai Facebook “f” Logo CMYK / .ai Conservation of the Venetian glass mosaics at St. George’s Church, Woolwich. BCD_04-15_ 86x124.indd 1 22/04/2015 1 RUPERT HARRIS CONSERVATION LTD CONSERVATORS OF FINE METALWORK, HISTORIC AND MODERN SCULPTURE www.rupertharris.com 020 7515 2020 mail@rupertharris.com Appointed Advisor to the National Trust since 1982. Accredited Member of ICON Image: John Cheere’s lead Medici lions returned to Stowe House SCULPTURE referred to require much less pigment content to achieve the same colour of mortar. As with all mortar matching, it is essential to match the cured and dried mortar trials with the dry mortar of the historic item before a selection is made. Fresh, damp mortars will appear more deeply coloured than dry, cured mortars. Pulhamite is renowned for its durability but has often been extensively restored. Unfortunately, much of this has been in the form of applying Gunite (a spray-applied modern Portland cement mortar) or by other such ‘over-coating’ techniques which do not take into consideration the importance of the historic surface. Such techniques often provide a covering of up to 50mm additional material that not only obliterates the original surface but also changes the form and outline of the rockwork. Undoing such misguided treatments can prove costly. The preferred approach is localised consolidation and careful matching to localised areas of lost surface coating, but not covering over the original surface. Conservators frequently underestimate the weather exposure of free-standing items in parks and on wall-tops or artificial rockwork that is permanently exposed to water and damp. Free-standing objects in parks are also exposed to snow coverings which thaw and re-freeze, damaging their fabric. Objects permanently in water or in damp areas have greater potential to absorb salts and are subject to winter freeze- thaw. Both in the design of mortars for repair and in the longer term planning for the conservation of the object these factors need to be taken into consideration. Further Information HL Childe, Manufacture and Uses of Concrete Products and Cast Stone , Concrete Series No 11, Concrete Publications Ltd, London, 1927 J Davis, Antique Garden Ornament , Antique Collectors Club, Woodbridge, 1998 English Heritage, Durability Guaranteed: Pulhamite Rockwork , 2008 (http://bc-url.com/pulhamite) AJ Francis, The Cement Industry 1796–1914: A History , David and Charles, Newton Abbot, 1977 C Hitching, Rock Landscapes: The Pulham Legacy , Garden Art Press, Woodbridge, 2012 BL Hurst, ‘Concrete and the structural use of cements in England before 1890’, Proceedings of the Institution of Civil Engineers: Structures and Buildings , Vol 116/3, 1996 W Papworth (ed), The Dictionary of Architecture , Architectural Publications Society, London, 1853–1892 SIMON SWANN is an accredited stone conservator with a longstanding interest in early cements and Pulhamite Rockwork. He is director of Simon Swann Associates Ltd (see page 92), a specialist conservation workshop working on sculpture and ornament in stone, terracotta and mortar based materials. He would like to acknowledge the help of many colleagues, clients, architects and grant-supporting bodies such as the Heritage Lottery Fund and Historic England, who have contributed to our knowledge of artificial stone through supporting analysis, investigations and conservation. Detail of the base of the dolphin tazza fountain showing mortar repairs to match the original surface finish and texture (Photo: Simon Swann)