Technical Case Study
Extract from the Conservation Report for Vertumnus, Pomona & Putto by Rupert Harris Conservation
Vital Maintenance
Lead statues will gradually collapse if not maintained. The works at Queluz were cast with an internal armature in place, surrounded by a plaster core. Due to exposure to the elements over time, water penetrates the lead surface through any small cracks or holes into the core. This rusts the internal iron armature and ultimately leads to a splitting of the lead and the collapse of what is effectively the skeleton of the sculpture. Splits in the surface of the leads can be exploited by plants which grow and cause further damage. The restoration works involve replacing all iron armatures with stainless steel, and rectifying the damage caused by time and past ‘repairs’ to the lead itself.
On first inspection the figure group of Vertumnus, Pomona & Putto was in poor condition, suffering from severe iron corrosion and rust jacking, which had lead to splitting and cracking in the lead. There had been some past attempts at repair using mortar fill, but these had not been successful.
The following areas of damage were identified, and these can also be seen on the diagram below.
Cracked, stained and vegetated
After restoration
The figure of Vertumnus:
Severe wide crack down spine to waist
Severe cracks at base of next
Severe cracks at left ankle and right ankle, heel and lower leg
Two large round holes, one in right forearm, and the other in left front shoulder
Cracks, holes and splits in fabric around waist and at joint with body
The figure of Pomona:
Large hole behind left knee
Cracks in back of right hand and right shoulder area
Severe cracks in base beneath both feet and around the back of the rock she is seated on
Severe cracks and loss of material where her left foot rests on the base
The Putto:
Severe cracks and breakdown of material between top of legs
The surface was covered with a significant amount of disfiguring brown staining and pustulated layers of original, degraded paint, particularly in recessed areas.
Twelve point plan
The following repairs were carried out:
The stone base was temporarily removed to allow the repairs to take place.
The figure of Vertumnus was removed from the group and this figure’s legs and arms removed to allow for the core and old iron armature to be removed. A section was also cut in the back.
The figures of Pomona and the Putto were also cut where necessary to allow removal of the core and old iron armature.
All the figures were pressure washed with water, both inside and out.
A new stainless steel armature was then constructed inside all sections of the figure group.
The figures were then reassembled , arm and leg sections with stainelss steel armatures were fed back into the correct position and the stainless steel armature welded together internally, through the opening in the back of Vertumnus and via the underside.
All joints and cracks in the leadwork were lead burned, and these repairs worked back using hand tools.
The surface of the repairs is then worked with hand tools and punches to replace the original detail and surface texture.
Stainless steel security fixings were then fitted into the base of the sculpture.
Due to the disfiguring level of brown staining on the sculpture, it was necessary to removed this before attaching it to its limestone base and subsequently its plinth within the garden. The cleaning was undertaken using a poultice in the form of a thixotrophic gel, comprised of fine grade fumed silica and a 1:20 solution of hydrochloric acid. This poultice was applied for a period of between 30 minutes and 1 hour, at which time it was washed off using low pressure water and a fresh poultice applied where necessary. This process was repeated until the areas of brown staining had been fully removed. Once this had been achieved, the sculptures were washed with a neutralising solution of 2% sodium hydroxide in water. This was followed by thoroughly washing all the surfaces of the sculpture several times to ensure removal of all chemical traces.
The sculpture group was than patinated using a dilute potassium polysulphide solution with a buffered acid base to produce a light chemical patina over the entire surface. This process is designed to provide a thin, unified patina, which in exposure to normal environments will develop into a naturally formed patina.
A bespoke open steel case was made and the sculpture carefully packed into it with padding and slings where necessary. The sculpture was then transported to the Palace of Queluz where it was reinstated on its plinth in the gardens.
Project partners and conservators
National Palace of Queluz, WMF-Portugal, Portuguese Government and IPPAR
Conservators – Rupert Harris, Tony Martin, Melvin Rodda and Jackie Rumsey of Rupert Harris Conservation
Transportation of sculptures – MTec International Ltd
Students - Marta Raposo, Maria Furtado, Valeria Vieir and Rodrigo Pires
Specialists - Dr Virginia Costa; lead research
