------------------;L 14 Terracotta tile are to be set aside unopened for later use a suitable storage area is to be provided to prevent any third-party damage. Upon unwrapping, any units thought not acceptable are to be advised to the manufacturer in writing. Units will be replaced free of charge if they have not been damaged subsequently, provided that the blocks have not been filled with concrete or installed on the building. 6.2 Filling: The hollow cellular voids of the blocks are generally expected to be filled with concrete. Unless the concrete fill is expected to add structural strength, it is recommended that a weak mix be used. A proprietary 'Light-A' concrete is satisfactory under normal conditions. Where an improvement in structural strength has been iclentifiecl, compliance with the specification of the structural engineer is advised. It is not recommended that blocks be used as permanent shuttering for cast in-situ structural concrete elements. 6.3 Installation: units are to be wetted prior to installation allowing 24 hours for the fill to cure. Units should be gauged horizontally and vertically to ensure that joints can accommodate manufacturing tolerances. Where necessary, units are to be cut on site to ensure a satisfactory fit and this is part of the installation contractor's responsibility. 6. 4 Check-outs: These are sections of block which are required to maintain the shape during firing but which have to be removed by the fixing contractor prior to installation. 6.5 Fixings: Generally in stainless steel, to provide bearing and restraint. Any structural design requirements are the responsibility of the supplier or the structural engineer. Any existing ferrous metals are to be treated to prevent possible damage to the terracotta due to corrosion. 6.6Cteaning down: Units are to be washed down during installation. Chemical cleaning compounds are to be avoiclecl unless professional advice on their use has been sought. Compounds containing hydrofluoric acid are known to damage terracotta and must not be used. 7 MAINTENANCE 7.l Visual inspection: Should be carried out on a regular basis and any failure of joints rectified. Associated works such as flashings, lead dressing, asphalt roofing should be checked for signs of deterioration. Any weep holes incorporated in the units should be melded clean to prevent water retention in the fabric of the building. 7.2 Cleaning: Specialist advice should always be sought before undertaking any cleaning work. The avoidance of damage to the terracotta should be the primary consideration. If possible compounds containing hydrofluoric acids should be avoided. 8 SUMMARY The selection of clay and glazes is often dictated by the choice of colour and finish required, particularly with restoration work. It is therefore not always possible to commit ourselves to achieving specific physical properties or tolerances. The manufacturer should be able to submit test results under the criteria defined above through its technical services department. Any requirement for testing should be advised to the manufacturer prior to submission of any quotation so that costs can be included and the manufacturing programme formulated accordingly. G Hollis, Commercial Manager, Ibstock Hathernware Ltd VICTORIANMOSAICS: CONSERVATIONAND REPAIR This article was presented to an audience, mainly made up of people who work within the practical sphere of conservation, at the 1995 symposium for the Conservation a/Architectural Ceramics organised jointly by English Heritage and United Kingdom Institute for Conservation. Its interest for Conservation Officers may lie in that it highlights some of the difficulties present in the restoration of mosaic floors. Because of their function, mosaic floors are usually to be found within public buildings in areas of heavy tread. New tesserae are no longer manufactured, and so replacements are generally made up by cutting whole new tiles of the correct colour into the size and shape required. This is, of course, labour intensive and therefore a fairly expensive process. It is hoped that the following cases will go some way towards helping Conservation Officers appreciate the time scales, and therefore the costs, involved in restoration of these sometimes plain, but sometimes wonderfully complex patterned floors. This is an overview of the treatment programmes undertaken on three separate Victorian ceramic mosaics, which encompass different purposes, situations and functions. The first, the Alliance Assurance Mosaic Roundel, was restored for museum display purposes. Reduction in weight and reversibility were requirements for this project. The second, the Entrance Hall Floor of the Jackfield Tile Museum, was repairedin situ, and is the main public entrance to the Museum. The requirement here was to consolidate a badly crumbling floor, replace badly damaged or missing areas to a condition able to cope with a growing number of visitors walking over the floor every day. The third, the entrance porch of St John the Baptist Church, Whittington, also in frequent use and badly damaged, was a holding operation until funds became available for complete restoration. Victorian ceramic mosaics are to be found in many of our public buildings, including banks, commercial buildings and offices, shops hotels and public houses. Many of them have been in constant use for over a hundred years and some of them, not surprisingly, are now in need of care and attention if they are to survive. REVERSIBLE MUSEUM DISPLAY. The Alliance Assurance Company mosaic (Fig 1) measures approximately 97 cm in diameter. It dates from 1892, CONTEXT 52
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