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Apollo in the Lab

Conservators apply 21st-century technology to learn more about the famed ancient bronze
August 8, 2016
Apollo the  Python-Slayer

Colleen Snyder Assistant Conservator of Objects

Apollo the Python-Slayer c. 350 bc. Attributed to Praxiteles (Greek, c. 400 bc–330 bc). Bronze, copper and stone inlay; h. 150 cm. Severance and Greta Millikin Purchase Fund 2004.30

 

Over the past nine months or so, many museum visitors have noticed and commented on the absence of our well-known ancient Greek bronze, Apollo the Python-Slayer. In his place stands a Roman white marble copy generously loaned by the World Museum, Liverpool. Since January, Apollo has resided in the objects conservation lab for an in-depth technical analysis, a collaborative project overseen by Michael Bennett, curator of Greek and Roman art, and myself. Though the bronze figure has been carefully studied previously, this continued scientific examination and analysis should help us better understand the work’s history—both ancient and modern. Many classical bronzes were melted down to reuse the material, so comparatively few large bronze sculptures like Apollo exist for study. Thus, the Cleveland Museum of Art has the rare opportunity to add to the relatively small body of knowledge about bronze casting practices for large figural bronzes during classical antiquity.

The first goal of the current study is to gain more information about the original manufacture of the figure, and we hope to be able to address, with greater certainty, these questions: Do all the parts belong together (both cast sections and repaired breaks)? Are all the parts ancient? What techniques were used in bronze manufacturing during classical antiquity and can they be identified? What is the composition of the bronze; does it vary between cast sections, and can the materials be sourced? Is it possible to reconstruct the original intended appearance of Apollo, including its patina, and the possible addition of gilding or other applied decoration? The second part of the study aims to provide further information about the history of the object after its original intended use—during archaeological burial, subsequent rediscovery, restoration, and display. What was the burial environment? How and when was the sculpture broken and damaged? How and with what materials was the sculpture reconstructed? Has it been restored more than once over time? Though it is possible that we may not be able to provide definitive answers to some of these questions, we are certain that the study will help us to understand better the complex history of this ancient masterwork.

 

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Borescopic Investigation

Borescopic Investigation Examining the modern repair material on the inside of Apollo’s head after removal of the plaster reproduction eye. Photo: Chris Bruns

 

Visual examination under magnification and with the aid of different kinds of lighting is a necessary first step for the study of any artwork. Having the sculpture off view has been invaluable for observing and recording surface details and for better documenting areas of restoration. One of the most useful nondestructive tools for this project has been a borescope, a long flexible tube with a built-in camera and fiber-optic light. This device has allowed us to see inside the sculpture. Recently, Apollo’s left eye, a modern plaster restoration, was removed to facilitate investigation of the interior. Using the borescope we can see where chaplets, or small square bronze pins, were pushed through the wax model of the head in order to hold everything in place during casting. The borescope has also let us see numerous modern repair materials, including resin and fiberglass, plaster, wire mesh, Plexiglas, foam, and even a piece of cardboard from a pair of German women’s pantyhose!

 

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Detail of Chaplet Hole

Detail of Chaplet Hole Some chaplet holes, where bronze pins were pushed through the wax model during manufacture, are visible on both the interior and exterior of Apollo. These observations are important for reconstructing how the figure was originally cast. Here is a detail seen in the hair on top of the head. Photo: Howard Agriesti

 

During previous study, Apollo was examined with x-rays. In the years since, technology has made significant advancements, including the use of computed tomography (CT) scanning for artworks. A CT scan of a bronze figure works much like it does with a human patient: the figure lies on a bed while the x-ray source moves around in a circular fashion. A sensor on the opposite side detects the x-rays that penetrate through the object. In this manner, all of the information about an object is captured and can be seen in slices. These slices allow us to view an object digitally, section by section, with much higher resolution than standard x-rays. Such information can then be represented in volumetric or three-dimensional form. The challenge is that the figure is a highly leaded bronze, which means that a high amount of energy is needed to penetrate the metal and obtain an image. Fortunately, our neighbors at Cleveland Clinic have generously offered their services. We currently are working with physicians and a physicist to see what information can be gathered.

 

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Apollo’s Hand In a CT scanner

Apollo’s Hand In a CT scanner at Cleveland Clinic. Photo: Colleen Snyder

 

While Apollo has undergone many nondestructive analyses, it is sometimes necessary to take samples in order to gain the most complete information about an object and its history. Recently, several extremely small pieces of metal were cut and embedded in resin, polished, and etched in order to look at metal composition and the layers of corrosion present. The appearance of these corrosion layers can tell us about the burial environment and provide information about additional weathering during subsequent rediscovery and display. Additional bronze samples were taken by boring small holes with a drill. These samples may tell us more about the raw materials used to make Apollo and where they came from. Though the samples are still being studied, preliminary analyses have again confirmed that the figure is composed of a highly leaded bronze that is appropriate for a sculpture cast during classical antiquity, and these new analyses have further confirmed that the work spent a long time buried in the earth, followed by sustained exposure outdoors.

One additional sample was taken that was not bronze. Just inside Apollo’s forearm are some small pieces of carbonized wood, covered by corrosion. Previous bronze analysis indicated that the sculpture may have been exposed to high heat, such as a fire, at some point in the past, and this carbonized material may hold an important key to understanding that event. A small sample is currently being carbon dated, and we may soon have an answer as to when that event occurred.

Apollo is scheduled to return to the galleries after the start of the new year, but research will be ongoing as results of testing are processed and interpreted. As the caretakers of this rare survivor of the classical tradition of making large figural bronzes, we will continue to learn from this masterpiece for generations to come.  

 

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Apollo in the Lab

Apollo in the Lab Colleen Snyder examines Apollo under the microscope in the objects conservation lab. Photo: Joan Neubecker

 

Acknowledgments The author would like to thank Cleveland Clinic and especially Dr. Andrew Godley, Dr. Gregory Videtic, and Dr. Jay Ciezki for their generosity with time, equipment, and expertise.    

 


Cleveland Art, September/October 2014