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Scientific methods inform conservation efforts in the quest to preserve cultural heritage

Man standing on scaffold repairs hanging paintingDAVE YODER/NATIONAL GEOGRAPHIC CREATIVE

Alberto Felici searches for gaps in a Vasari mural that experts can probe without causing further damage.

Fifty years ago on 3 November 1966, after a long stretch of heavy rain, the Levane and La Penna dams in Valdarno, Italy, began to leak, releasing water toward the city of Florence. Fearing that the dams would burst, on 4 November, engineers discharged a massive amount of water that coursed through the city streets at an astonishing 37 miles per hour (1). The raging waters covered much of Florence, killing dozens of people, displacing thousands more, and damaging countless books and works of art. Over a million items in the Biblioteca Nazionale Centrale di Firenze alone were completely submerged.

Known collectively as the “angeli del fango” (mud angels), art conservators, scientists, and concerned citizens descended on the beleaguered city to offer assistance. But volunteers were met with daunting challenges, including sparse laboratory space and a general lack of instrumentation for assessing the damage.

In a recent interview, Robert Feller, a renowned American conservation scientist, recounted how improvised equipment was assembled on site. “I was looking for a polarizing microscope, something to see the minerals coming out of the frescoes,” he recalls (2). “I went downtown and bought two polarizing sunglasses and I made a polarizing microscope.”

When the flood hit, scientific technologies were starting to become permanent fixtures in museums and cultural institutions. In the years since, art conservation science has developed into a full-fledged discipline, using state-of-the-art instrumentation to analyze and treat works of art.

Science Meets the Hidden Profession

In 1899, Edward Waldo Forbes purchased a 15th-century panel painting by the Italian artist Girolamo di Benvenuto on behalf of the Fogg Museum at Harvard for $100. Its condition was so poor that no one else could see its potential, yet he found himself moved by it (3).

When Forbes became the director of the museum, his interest in restoring this and other paintings in the museum’s collection led him to establish a new department—the Department for Technical Studies—composed of conservators, historians, and scientists, including George Stout and Sheldon Keck. [Stout and Keck would go on to serve as “monuments men,” tasked with recovering cultural objects stolen by Nazis during World War II. In his 13 months of service in Europe, Stout alone aided in recovering tens of thousands of cultural objects (4).]

The Department for Technical Studies was dedicated to the scientific study of art and began disseminating information about its work in a new publication entitled Technical Studies in the Field of the Fine Arts. The idea of conservation as a hidden profession with carefully guarded treatment methods soon began to fade. Forbes is widely credited with laying the foundation for modern conservation science.

In the mid-20th century, scientists who worked with museums and at cultural heritage sites typically trained in biology, chemistry, physics, and engineering and were drawn to scientific aspects of art and conservation out of their own curiosity and interest. A greater awareness and appreciation of art, as well as the development of more advanced scientific instrumentation, led to a growing recognition of conservation science as a discipline unto itself. Soon, cultural institutions in North America, Great Britain, and Europe began creating or expanding their own scientific laboratories. This quickly led to collaborations with research institutions and the chemical industry, which sought to characterize existing conservation materials and develop new ones specifically for the maturing field.

When the Florence flood hit in 1966, museums and cultural institutions around the world were ready to provide assistance. Samples of accretions from frescoes were sent to the Mellon Institute of Industrial Research in Pittsburgh for x-ray diffractometry, and optical microscopy was employed extensively to inspect paintings, sculptures, and frescoes for damage.

Striking the Right Balance

Historically, conservation scientists mainly focused on paintings, where visual aesthetics were a key factor and the critical eye of a conservator often aligned with the goals of the scientist. This union led to the development of a number of new synthetic varnishes and adhesives for the conservation of paintings (5).

Cars stuck in a floodASSOCIATED PRESS

Fifty years ago, a devastating flood damaged countless works of art and cultural objects in Florence, Italy.

But conservation scientists face unique challenges—for example, the need to balance scientific rigor with museum policies that limit physical alterations to works of art. These two requirements sometimes clash, and the challenge of obtaining comprehensive data from limited samples can be incredibly difficult.

Different philosophies, protocols, or ideas about which treatments should be pursued can also arise. In postflood Florence, for example, Italian, American, and British experts reportedly disagreed on what type of processes to use to treat mold in library collections and salvaged materials (6). Experts from Harvard recommended thymol, and the United States sent large quantities to Florence for the American volunteers to use. However, experts from the British Museum recommended topane and advocated its use over thymol because “it was possible to grow mould on a thymol treated paper (1).” Yet, topane was known to be a skin irritant. One could speculate that the disagreement may have had more to do with reputation than with science.

Science in Situ

When a cultural material cannot travel to the laboratory for analysis—because it is on display, or it is too fragile to be moved, or the expense and risk associated with off-site transportation and storage are prohibitive—conservation efforts are often performed on site. Small, portable instruments now allow conservation scientists to conduct quick assessments and analyses on items in the field or on permanent display and on large sculptures and frescoes.

Launched in 2004, the Mobile Laboratory (MOLAB) was the first state-of-the-art collection of portable scientific instruments dedicated to the preservation of cultural heritage in Europe. To date, MOLAB instruments have been used for a variety of purposes on a wide range of collections—from identifying pigments on Old Master paintings to studying modern synthetic polymeric binding media. It has also been instrumental in monitoring the conservation state of various cultural objects, including Michelangelo’s David (7, 8).

Conservation Gets Personal(ized)

Risk assessment and preventive conservation methods are now a standard practice in cultural institutions and are tailored to each institution’s unique collection, location, and climate. Natural disaster recovery protocols, cultural sensitivities, and energy sustainability goals are also considered in these assessments.

A culturally sensitive example of such a program can be found in Luang Prabang, Laos, where conservation professionals funded by the British Library have partnered with Buddhist monks to preserve a rich archive of photographs depicting monastic life. Rather than imposing a strict climate-control system in the modest temple that houses the collection, a system was developed in which caretakers actively monitor for insects and other issues. Local craftsmen were charged with building the archival cabinetry and housing as a way to ensure sustainable construction and increase awareness of the collection in surrounding communities (9).

Art and Science: Stronger Together

Volunteers holding a paintingASSOCIATED PRESS

Mud-covered volunteers retrieve a painting from the murky Florence flood waters on 7 November 1966.

Cross-fertilization between disciplines has facilitated greater accessibility to instrumentation and expertise, prompting novel applications of existing technologies in the examination of art. An excellent example is tomography, which allows researchers to examine the internal structures of mummified remains and works of art. The fragile En-Gedi scroll, for example, was recently digitally unfurled with computerized tomography, revealing text from the first eight verses of the Book of Leviticus (10). Likewise, hyperspectral imaging, developed for military and geographic applications, was recently applied to a panel painting by the early-Renaissance artist Cosimo Tura in order to map paint binding media and identify pigments without the need for physical sampling (11). Proteomics, an invaluable tool for medicine and biology, is also currently used for species identification of modern and ancient leathers, furs, and parchments (12).

The study of traditional material has also led to improvements in scientific techniques. For example, a recent study revealed that the luminescent properties of micronized Egyptian blue pigment provide a sharper contrast between dark backgrounds and bright fingerprints than ultraviolet-based dusting powders, enabling the detection of latent fingerprints on patterned and reflective surfaces (13).

Always searching for new and novel scientific methods, conservation science has begun to employ spectroscopic mapping—especially elemental mapping with micro x-ray fluorescence (µXRF)—where advances in array detectors are enabling quick and comprehensive analysis of works of art. Elemental mapping of Edgar Degas’s Portrait of a Woman was recently completed with the help of a Maia 384 detector array and the XRF microscopy beamline at the Australian Synchrotron, for example. T he results yielded an exciting revelation: The image long known to be concealed behind the famous portrait is, in fact, a portrait of another woman (14).

Valuing Cultural Heritage

Technical studies of works of art were historically motivated by the need to confirm a piece’s authenticity or provenance or to aid in a conservator’s treatment decision. But many museums now incorporate scientific and technical analyses into public outreach, exhibition catalogs, and education programs. Programs like the BBC’s Fake or Fortune?, in which investigators team up with conservators and scientists to determine whether works of art are authentic, reinforce the idea that there is a growing interest in this field among the general public.

Days before the 1944 invasion of northern Europe, General Eisenhower released a memorandum that stated “… in the path of our advance will be found historical monuments and cultural centers which symbolize to the world all that we are fighting to preserve. It is the responsibility of every commander to protect and respect these symbols whenever possible” (15). Just over 20 years later, museums and other institutions around the world came together again when Florence’s cultural heritage was in trouble. Today, new and continuing threats, including climate change, natural disasters, and armed conflict, demand a united front when it comes to protecting and preserving rare works of art and cultural objects. As science continues to inform the field of conservation, and vice versa, we stand better prepared than ever to rise to this challenge.

References

    1. S. Waters, Waters Rising: Letters from Florence. (Legacy Press, Ann Arbor, 2016).
  1. A. Shugar, R. Ploeger, Oral interview with R. Feller and C. Tahk (2015).

  2. F. G. Bewer, A Laboratory for Art: Harvard’s Fogg Museum and the Emergence of Conservation in America, 1900–1950 (Harvard Art Museum, 2010).

  3. R. M. Edsel, Harvard Magazine (Cambridge, 2010); http://harvardmagazine.com/2010/01/monuments-men-rescuing-art-stolen-by-nazis.

  4. E. René de la RieC. W. McGlinchey, Studies in Conservation 35, 168 (1990).

  5. S. K. HeningerR. M. KingdonM. P. Gilmore, Renaissance Quarterly 20, 81(1967).

  6. C. MilianiF. RosiB. G. BrunettiA. Sgamellotti, Accounts Chem. Res. 43, 728(2010).

  7. B. Brunetti et al., Topics Curr. Chem. 374, 1 (2016).

  8. M. C. Jürgens, in Topics in Photographic Preservation, B. Bernier, C. Moore, Eds. (American Institute for Conservation of Historic & Artistic Works, Washington, DC, 2009), vol. 13, pp. 2136.

  9. W. B. Seales et al., Sci. Adv. 2, e1601247 (2016).

  10. K. A. Dooley et al., Analyst 138, 4838 (2013).

  11. S. DallongevilleN. GarnierC. RolandoC. Tokarski, Chem. Rev. 116, 2 (2015).

  12. B. ErringtonG. LawsonS. W. LewisG. D. Smith, Dyes Pigments 132, 310(2016).

  13. D. Thurrowgood et al., Sci. Rep. 6, 29594 (2016).

  14. Dwight D. Eisenhower, General, U.S. Army, “Preservation of Historical Monuments,” Memorandum for G.O.C. in Chief, 21 Army Group; Commanding General, 1st U.S. Army Group; Allied Naval Commander, Expeditionary Force and Air C-in-C, Allied Expeditionary Force. (Division, General Staff, Supreme Headquarters Allied Expeditionary Forces, Allied Operational and Occupation Headquarters, World War II, RG 331, 1944).

About the author

Department of Art Conservation, State University of New York College at Buffalo, Buffalo, NY 14222, USA.