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New life for Peter Pan and Wendy - the art and science of bronze conservation in Dunedin

Gary Blackman - 3/12/02

Peter Pan
Bronze sculpture of Peter Pan at Dunedin Botanic Garden by British sculptor Cecil Thomas, 1964
While working on Cecil Thomas's bronze Peter Pan sculpture in the Dunedin Botanic Garden, conservator Francois Leurquin was asked about his work by two young women visitors from Denmark and France. They had seen a photograph of the statue in a brochure and had come to Dunedin on their way to Australia especially to see it, much as New Zealanders visit Copenhagen to see the Little Mermaid. Francois was very happy to answer their questions and to tell them about the two sculptures on the lawns near the duck pond at the Botanic Garden.

The two charming statues of Peter Pan and of Wendy and friends were the work of British sculptor Cecil Thomas. Standing about 2 and 3 metres high, they were created in the 1960s, and generously given by Dunedin philanthropist Harold Richmond for the enjoyment of children who love to touch and caress the bronze surfaces and to search out the tiny people and animals hiding in the hollows of the tree trunk bases. Over the years favourite parts have become bright from repeated touching.

Wendy
Bronze of Wendy and friends at Dunedin Botanic Garden by Cecil Thomas, 1967
Inevitably, time and exposure to the atmosphere and human mishandling takes its toll of bronze sculptures and discolours and corrodes or otherwise damages the original patinated bronze surfaces. Such changes are to be expected and fortunately they can be mostly reversed as part of their care. In Dunedin the skilled work required has been carried out over the last three years by resident conservator Francois Leurquin.

Squirrel
Detail of squirrel at base of Peter Pan sculpture
I decided to ask Francois about his work which first attracted public attention when he started on the restoration of the large and much-photographed bronze sculpture of Robbie Burns overlooking the Octagon in Dunedin. For several months the scaffolding and screens intrigued both the Dunedin public and visitors who converge on the nearby visitor centre. More than once Francois was amused to be told by British tourists that they had included Dunedin on their itinerary in order to see the statue of Robbie Burns not knowing that several copies of the same sculpture can be seen in the UK.

I arranged to meet Francois in November during a lunch break from his almost completed work of restoring woodwork in the historic Dunedin Courthouse. I asked him about the skills and knowledge he brings to his work on outdoor bronze sculpture.

Fairy
Detail of fairy on base of Wendy sculpture
He began with a definition of bronze: "a durable alloy of copper and tin with an addition of small amounts of lead and zinc". It lends itself to casting, for example by the lost wax process, which produces a hollow form and allows more than one copy to be made of any sculpture. Left to age naturally outdoors, bronze often takes on the green colours of the various compounds of copper formed by exposure to the atmosphere. Because this texture and colour do not suit traditional bronze work, sculptors generally have the surfaces of their work chemically treated by patination, an artificial aging process that can be controlled to give the colour and quality of surface patina desired by the sculptor to enhance the appearance of the work. Once outdoors however, the aging process continues slowly, not always with pleasing results. Pollutants in the atmosphere and the attentions of birds and humans cause discolouration, encrustation and corrosion.

The process for conserving and restoring bronze
Faced with conserving and restoring bronze, Francois Leurquin follows a number of well-defined steps. Initially he assesses the condition of the object and outlines for his client what must be done to reverse the undesirable effects of the sculpture's life outdoors and to make good any defects or physical damage. Before starting he has scaffolding and screening erected with an electrical supply and secure on-site storage.

The first conservation step is to clean the surface of dirt and loose accumulations with water and detergent applied under high pressure. He can then see the nature and extent of corrosion and accumulated corrosion products. He may take samples for chemical analysis to identify the products formed by exposure to the atmosphere. The four usual agents of deterioration in the air apart from oxygen and water are sulphur dioxide, hydrogen sulphide, ozone and nitrogen dioxide. In Dunedin, the main corrosion product is a sulphate derivative of copper known as brochantite. This accounts for the green colour that commonly develops on bronze in a sulphurous atmosphere. It is porous, takes up water and because it is soluble, it leads to ongoing selective loss of the copper from the alloy.

The second step is to remove the layers of corrosion products without damaging the metal's smooth surface. This is again done with water under pressure but with the addition of washed beach sand. This sounds drastic but by controlling the pressure and angle of the jet, the relatively coarse grains with rounded edges can remove 90% of the accretions without damaging the metal. A soft’ abrasive and a final chemical treatment removes the remaining products of corrosion.

The third step is to repatinate the cleaned surfaces by applying heat and chemical solutions to achieve the colour of natural aging in the absence of corrosion. After discussion with city council and Historic Places Trust representatives it was decided that Robbie Burns should be given a classical bronze patina’ of dark green on a dark brown background equivalent to a century of aging.

Finally, the whole surface is protected with a microcrystalline wax containing a corrosion inhibitor. The statue should now look like a well-maintained monument of its age, and certainly not like a new penny.

Francois Leurquin's career
As his name suggests, Francois Leurquin is French, though born in Africa. He trained at the Sorbonne in Paris, came to Auckland in 1990, and the following year joined the staff of the Otago Museum as conservator. After eight years he successfully set up on his own as a freelance conservator and consultant. So far he has found most of his work in Dunedin and in the South Island, but he has also had jobs in the North Island and in the Pacific as far afield as Vanuatu, Tahiti and Noumea. A very visible part of his work in Dunedin has been the restoration of several public sculptures. He is an enthusiastic ambassador for public art and its proper care.

Photos for this article were taken by Gary Blackman.

Gary is a retired scientist with an interest in local history and photography. A retrospective exhibition of his photography is to be shown at the Dunedin Public Art Gallery from June 2003.






 
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