The construction methods, problems and conservation techniques associated with lead statuary.
In the late 17th century, lead became a popular material for garden statues, fountains and ornaments. It was cheaper than bronze or carved stone, so it was used to produce multiple copies of admired sculpture from earlier periods. The surfaces of lead statues were often finely chased after casting with punches and chisels. The statues were then painted to imitate marble, stone or bronze, decorated with lifelike polychromy or gilded with gold leaf.
Due to the metal’s softness, lead statues were made in a slightly different way to other castings and the foundry did not remove the core material (gypsum) after casting. There are potentially serious inherent structural problems with lead sculptures, so they fell out of fashion after about a hundred years. Since then, many historic examples have been lost. Surviving lead statues need careful protection, and early detection of problems is critical.
Water entering the statue through a defect in the lead will soak into the core and cause the internal wrought-iron armature to rust and expand, eventually splitting the soft lead.
Poor casting techniques or impurities in the lead may produce areas of structural weakness.
Lead is vulnerable to impact damage and is frequently vandalised. Squirrels like to gnaw on lead, which can also do significant damage.
Before the late 19th century, repair techniques were limited and old repairs generally failed.
Inevitably, painted surface finishes will wear away on exposed areas of lead sculptures. However, remnants can sometimes be found in crevices, and even tiny samples can be analysed to reveal the original decorative scheme.
Over time, unpainted lead will develop a protective natural patina of whitish grey to dark grey. In recent years, lead surfaces have started to develop dark brown to purple deposits of lead dioxide. Although these are disfiguring, they are not harmful.
Typically, treatment of lead statuary involves cleaning and repair. This work requires a specialist metalwork conservator with relevant experience working on historic lead statues.
The method of cleaning will depend on the extent of the soiling, the condition of the coatings and the fragility of the metal. It may involve washing by hand (using scrubbing brushes, warm water and a gentle biodegradable detergent), low-pressure water jets or high-pressure steam. The appropriate technique and settings should be selected by a metals conservator based on trials. Abrasive cleaning should be avoided because it may damage the lead surface.
Areas of sound patina and traces of historic paint or gilding on a lead sculpture are comparatively rare. They need to be recorded and protected during cleaning.
Repair works may have to take place in the studio, and moving heavy fragile objects will require an experienced conservator.
When an armature has to be replaced the work is often invasive. However, it will secure the future of the statue and may reduce the risk of it being stolen, as the new armature is fixed to the plinth. The plaster core material is usually removed at the same time as the original wrought-iron armature. This is because the new structural armature is built in stainless steel, and the core is not required. Note that no substitute core material, such as expanding foam, should be used.
The repaired areas of the lead statue will lack their natural patina. The conservator can disguise these areas using patination chemicals and pigments that will be replaced, over time, by the formation of a natural patina.
Should lead statuary be repainted?
If the statues were originally painted to match the stonework façade of a great house, for example, it may be desirable to restore the painted surface to recreate the architect’s original aesthetic intention. Although repainting resolves the lead dioxide (purple-brown staining) problem, there is currently much academic debate about its appropriateness. Issues include:
- Historical accuracy: is there good paint analysis or other evidence of the colour of the original coating on which to base the redecoration?
- Curatorial considerations: will the freshly painted sculpture fit with historic surroundings? Interpretation may be required to inform visitors of the historical context and reasons behind the restoration of the original painted surface
- Cost implications of long-term maintenance