Sculpture and Monuments

Bronze sculpture is made by casting in sections and then joining these together by brazing, soldering, or pinning. As the castings are hollow, an internal armature is required to provide support to the sculpture. The surface would then be finely worked to disguise the joints and to add further detail, then coloured using a variety of chemicals to create an artificial patina. Over this a varnish, shellac, wax or oil would be applied to protect and enhance the colour.

If protective coatings are not maintained, outdoor bronzes lose their original artificial patina and surface coating, leading to slow corrosion of the bronze and the development of a naturally formed, green patina. The bronze can be returned to its original colour (usually a dark brown) or the natural patina can be retained. A natural patina can sometimes include disfiguring marks, which can make the sculptural form difficult to read, but these can be removed and the surface manipulated to a cohesive whole. We use traditional methods and chemicals to conserve or restore the patina. Similarly, structural repairs are made using the traditional construction methods, though if the original iron armature has corroded, it may be necessary to replace it with a new stainless steel armature and integral security fixings.

Small, interior bronzes are much less vulnerable, but may have suffered from improper cleaning, poor handling or inappropriate restoration in the past. We can also rectify these problems.

The production of lead sculpture reached its height in England during the 18th century. Most was cast in one piece, and sand or plaster used as a core material. The iron armature was left inside sculptures to provide support.

The original iron armature will inevitably corrode and, as it does so, the rust expands to up to ten times the volume of the original iron. So lead sculpture is particularly vulnerable to splitting and collapse as the armature is weakened. Lead itself is generally resistant to corrosion and, if unpainted, the surface will develop a protective natural patina. As a soft material, impact damage is commonly found on lead sculpture in the form of superficial dents and scratches to the surface and as such it is very vulnerable to vandalism.

The conservation of lead sculpture often necessitates removal of the original armature and core material followed by the insertion of a new stainless steel armature. This may require cutting patches and sections to allow access (take a look at our example pages for more details). This process restores the structural integrity of the piece and if performed by experienced conservators, the sculpture will retain the appropriate, aged appearance and will be structurally stable.

We actively promote good practice in the care of lead sculpture, and to this end we have produced additional information pages which we hope may be helpful to those responsible for the care of lead sculpture, to students and to practitioners. These are:

Common forms of damage on lead sculpture

Poor techniques to be avoided when conserving lead sculpture

Lead dioxide formation on lead

The process of electrotyping, or ‘electroforming’, was developed in the 1830s. It satisfied the Victorian enthusiasm for ingenuity of invention in industrial processes and was an economical way to manufacture large-scale objects. Either a positive wax model of the object, or a negative mould was placed in a copper plating tank and copper was allowed to deposit itself by electro-deposition onto the surface of the objects, until it had built up to a structural thickness. Large sculpture was made in sections using the mould deposition option. Each copper section was then cleaned and joined together by brazing or soldering. Electrotypes can be patinated similarly to bronzes, but now frequently have a natural, green patina which has developed on the copper over time. Either finish can be reproduced to disguise any repairs. On electrotype sculptures, the thin copper shell will corrode if not cared for, allowing water into the plaster core, the resulting expansion of the core and armature materials produces splits and eventual collapse. We effect repairs by reproducing any large missing or heavily damaged areas using copper sheet, and by reinforcing weak areas using copper or fibreglass resin. Usually such objects require the replacement of their original ferrous fixings with new stainless steel security fixings and if necessary an armature.

The manufacture of large-scale sculpture in zinc was only in fashion for the short period 1840 - 1900. The sculptures were cast in sections and assembled using lead soldered joints, which were additionally pinned onto structural elements such as iron straps or frames, or zinc plates, for extra strength. The majority of this monumental sculpture was intended for exterior display and was generally finished to resemble bronze or stone. To achieve the bronze effect the completed sculptures were frequently electroplated in copper. In Britain, the firm of Elkington’s were instrumental in the development of electroplating technology and often finished zinc sculpture imported from Germany, France or America. Today, zinc sculptures sited outdoors have usually lost their original surface coatings and copper plating through corrosion, exposing the grey coloured zinc. The corrosion causes a very pitted surface in the zinc, accompanied by failure of the lead solder joints which compromises the object's structural stability and leaves it vulnerable to serious fracture and ongoing corrosion. We have carried out much research in this field and developed techniques to repair structural damage and restore the corroded surface to replicate the original 'bronzed' appearance.

The production of cast-iron sculpture began during the industrial revolution in the nineteenth century, as iron casting skills were developed and new production techniques made iron a cost-effective material for sculpture and ornament. As iron rusts rapidly if unprotected, a high percentage of iron objects including sculptures were originally painted, either naturalistically or to resemble other materials such as bronze or stone, traditionally using lead-rich oil-based paints. Cast iron is a brittle material, making it susceptible to impact damage and stresses caused by expansion rusting of construction joints in the object. Cast iron can be repaired using a range of techniques such as pinning, stitching or welding. However great care is required when attempting repairs, especially if heat is involved in a process, such as welding, as localised thermal expansion can induce further cracking and subsequent structural failure. Missing or severely damaged elements can be recast and replaced. It is important that existing paint is analysed so that original paint schemes can be identified and reapplied as much iron sculpture has been over painted many times in its life.

Although we are primarily known for the conservation of metal, we also frequently conserve objects made from wood, ceramics, terracotta, plaster, wax, stone and mixed media. Please take a look at some examples.

Please see the examples below that represent a selection of conservation, maintenance and consultancy projects we have carried out on public sculpture, memorials and monuments:

We have conserved many war memorials in the course of our experience in the conservation or restoration of public sculpture. These can take the form of outdoor monuments or indoor, wall-mounted plaques of brass, bronze, often with engraved and enamelled detail, or of electrotype, marble or wood.

The plaques and lettering on these monuments bear great significance, and we are also experienced in the restoration of missing or damaged lettering of all kinds, and in the production of new memorial plaques.

The funding for such projects and is often raised by charities and veterans’ organisations. See the links page for further information on these bodies.