Caravaggio in Focus

Following a year of study, The Crucifixion of Saint Andrew, painted by Michelangelo Merisi da Caravaggio, will undergo a comprehensive conservation treatment—and for the first time in the museum’s history, part of the work will be done in public.

The museum has a long tradition of the highest care of its world-renowned collection to ensure optimal preservation and conservation standards. The conservation department, which traditionally conducts its work behind closed doors, invites visitors to view the process. Beginning in June, after months of preparation, a fully equipped paintings conservation lab in the museum’s Focus Gallery adjacent to Gallery One will allow visitors to experience the first phase of conserving one of the most important paintings in the museum’s collection. The public will witness firsthand the planning, scientific research, equipment, insight, skills, and experience required for a large and particularly complex conservation project.

The exhibition will be supplemented with high-resolution technical photography, including infrared imaging, digitized X-rays, and photomicroscopy, to document the materials and techniques used to create the painting. These technical images, which provide insight into the painting’s construction, also illustrate how the painting has been compromised aesthetically by its long history.

Conservation science and imaging have advanced exponentially since the painting entered the collection in 1976. As scientific instruments and analytical equipment innovate with greater spectral sensitivity, more detail can be discovered about the original materials and techniques used by the artist, as well as conservation materials used in prior treatments. The emerging field of technical art history combines this scientific evidence with historical accounts and artistic trends to deepen our knowledge of how artworks were created.

As a part of the newly established Keithley Institute, a partnership between the art history department at Case Western Reserve University and the Cleveland Museum of Art, a PhD program joining art history theory with object-based study will allow students to work with the conservation department to study Caravaggio’s masterpiece from a technical viewpoint. In order to achieve a holistic understanding of the painting, the conservation department will display this aspect of art history to the public as well. 

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Beneath the Surface: Construction and Condition

When we look at a painting in the galleries, how its condition or a previous restoration might affect our understanding of it is rarely immediately apparent. Even experienced conservators, who can identify most of these complexities, often marvel when looking at a work through a microscope or reading an X-ray. What lies beneath the surface can be revelatory, and Caravaggio’s Crucifixion of Saint Andrew is no exception.

X-raying a painting is one of the best of methods of visualizing its internal construction. The first X-rays of the Caravaggio, made even before the painting entered the collection, revealed a repeating diamond-weave canvas used as the original support (shown above). While the use of patterned tablecloths is unique, they are not that uncommon in Italian and Spanish paintings from the 16th and 17th centuries. The overall X-ray also reveals fairly sizable tears and multiple canvas inserts with a different weave structure to fill holes in the original canvas.

In addition, the X-rays uncover delicate lines or incisions cut into the ground layer. Even though some debate continues over the exact purpose of these incisions, most scholars agree they were initial guides to position Caravaggio’s figures, or possibly to reposition his models. The incisions in our painting appear on the X-rays as faint white lines in areas painted over with a lead white pigment.

A few of these incisions in the area of drapery of the figure standing on the ladder were discovered when Caravaggio’s painting first entered the collection. During this most recent examination, however, many more incisions have been found by using the museum’s new Osiris infrared camera, including a very precise line that follows an early alteration (pentimento) in the first placement of the old woman’s arm.

Aesthetic Problems Associated with the Varnish and Paint Layers

A thorough examination by Ross Merrill at the time of the acquisition raised questions about materials used in a prior restoration before The Crucifixion of Saint Andrew entered the CMA collection. Merrill, the museum’s paintings conservator at the time, voiced concern with areas of cloudiness in the varnish and possible blanching in the paint. Blanching is a condition that imparts a bleached-out appearance over a painting’s surface. Merrill suspected that reversing this problem would require a complete retreatment of the painting, which was never considered until now.

In 2013 the Caravaggio was taken to the paintings conservation lab for a preliminary investigation to determine the exact cause of the blanching and investigate the painting’s overall condition, including its structural stability. The investigation linked the blanching to surface coatings used in earlier restorations that had blocked proper varnish saturation of the paint surface. In addition, an interim varnish, as part of a multi-layered structure from a 1974 treatment, was contributing to the poor saturation and creating stress fractures and traction cracking over the surface. Traction cracking occurs when two incompatible coatings with different properties are placed over top of each other.

In order to fully appreciate Caravaggio’s masterwork, all previous conservation efforts will be removed to reveal the original paint surface. This includes the complete removal of aged varnish layers and discolored retouching, exposing old tears and canvas inserts used to repair holes and losses to the canvas.

Conservation in the Focus Gallery 

The first step, after the technical examination, is to remove all of the visually disruptive varnishes and retouching from the painting’s surface. The public is invited to witness this process, a rare look into the normally secluded world of conservation. After the exhibition, the conservation will continue in the paintings lab until the work is completed in late 2015. The painting has significant potential for improvement, and the treatment is expected to be transformative. Caravaggio’s The Crucifixion of Saint Andrew is scheduled to return to the galleries in time for the museum’s centennial in January 2016.  

Cleveland Art, May/June 2014