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 89 MASONRY 3.2 Production of both architectural ornament and free-standing sculptural elements mainly took place in established workshops where moulds, probably either in wood or plaster, were used. Some items may have been sculpted directly in the cement material, but such items are likely to be rare. Many of the larger sculptural elements were cast in multiple pieces and later assembled using various armatures. Armatures were also incorporated into cast ornaments during the casting process, mainly to provide initial strength. Austin, for example, is known to have used ferrous armatures wrapped in sheet zinc or similar non-ferrous metal within cast elements, and to have used sandstone armatures to join separately cast elements together. Tile or brick was also often incorporated into casts, probably to restrict any possible shrinkage, provide some minor strengthening and save cement. Often casts were made in hollow sections. This was particularly the case for items that appear bulky but are effectively relatively thin walled, such as pedestals and bases. In such cases the interior is often lined with tile creasing (in effect courses or layers of clay tiles) bedded in Roman cement even if the exterior is in early Portland cement. This technique allowed for easier site handling of objects and a reduction in material costs. There is no evidence that Pulhamite artificial rockworks were ever pre-cast and placed, all examples seen by the author have been built in situ. Although cement-based wood imitations, such as rustic wood bridge hand rails, may well have been composed of pre-cast cement materials (examples can be seen at Antwerp Zoo but their origin is unknown). It is important to realise that the production of objects in a series of casts allowed for some discreet adjustments to the assemblage of casts. For example, Austin’s Eagles could be posed with their heads looking in either direction according to which type of head was selected. This allowed the production of matching pairs for gateways or other features. Similarly, the dolphins produced by the same firm could appear in various combinations and assemblies. Similar use of moulds can also be seen in Coade stone products. Many of the artificial stone manufacturers produced very similar ornaments, making it difficult to reliably attribute a design shown in a catalogue to a particular manufacturer. PRELIMINARY ANALYSIS AND INVESTIGATION Close inspection of the object or landscape scheme will aid an initial understanding of its construction, materials and form. If a series of objects is to be inspected then a survey sheet defining the critical aspects of the inspection is a very good aid, along with a detailed photographic survey. Simple techniques like wet brushing of the surface to reveal the original colour and texture of the surface are also strongly advised, especially in the case of items beneath trees where there is a substantial build-up of organic growth. Although some defects will be obvious, the first inspection often gives only a limited understanding of the object’s condition. This is particularly true where it is half- buried by soil, as is often the case, or where a feature projects from a wall, restricting full investigation and raising questions about the nature of the fixing. Invasive investigations are often not welcomed at the initial stages. In addition, the person investigating may be confronted with a wide range of materials, from natural stones (including tufa or imported materials) to binders, aggregates and pigments. Careful inspections will invariably include a range of materials analysis. Sometimes it is useful to inspect objects on site alongside a consultant geologist because this often helps provide immediate insight into the range of materials. For identifying mortars and binders, a full petrographic analysis is the best approach, and this can be supported by scanning electron microscope (SEM) work where necessary. The knowledge of the analyst is a critical factor as the analysis of early cement binders is a complex area. However, there are a number of indicators which can help to identify the type of binder used. These include the presence and nature of un- hydrated cement grains and the chemical analysis of these grains by SEM spot analysis. Pigments in the mortar are best identified by a pigment specialist, while stone aggregates are best identified by a geologist using petrography or simple observation. DEFECTS AND CONSERVATION Understanding the material composition and the method of construction is clearly critical to the development of a good conservation policy. However, understanding the historical significance of the item and its producer is equally important. In the recent past too many items have been replaced with modern reproductions without any assessment of their historic significance. Not only do many of these items reflect important technological developments in the use of early cements and casting techniques which were to influence 20th-century concrete development, but some workshops also used well-established sculptors and designers to develop their ornament. Historic and original items of artificial stone may therefore have considerable value both as works of art and as original antiques, which would be lost if they were replaced with modern reproductions. As well as helping to understand the colour and form of the surface, cleaning is sometimes required for a full condition assessment. However, the process may remove the patina of age which is part of an object’s significance, and may also cause irreparable damage to the substrate itself. Each assessment for cleaning must be made following trials on the specific object but the options are likely to include non-abrasive techniques such as wet brushing (water and a suitable non-abrasive brush), dry brushing, or super-heated steam cleaning (such as Therma Tec and Doff). Pulhamite Artificial Rockwork at Madeira Walk, Ramsgate in 1901 – the feature no longer survives (Copyright The Francis Frith Collection) Pulhamite rockwork on the edge of a three-acre lake constructed in 1880 at St Stephen's Green, Dublin (Photo: Simon Swann)