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Investigating Art Objects through Collaborative Student Research Projects in an Undergraduate Chemistry and Art Course Gary Wells† and Michael Haaf*,‡ †

Department of Art History, Ithaca College, Ithaca, New York 14850, United States Department of Chemistry, Ithaca College, Ithaca, New York 14850, United States

‡

S Supporting Information *

ABSTRACT: Inspired in part by Chemistry Collaborations, Workshops, and Community of Scholars workshops, the Chemistry and Art course offered at Ithaca College is team-taught by a chemist and an art historian, underscoring the complementary nature of the two disciplines. The course, populated primarily by nonscience majors, highlights the importance of using both historical knowledge and empirical measurements to address particular questions about a work of art. The course culminates in a collaborative student research project in which students must select a nonaccessioned art object, generate a series of questions about the object, and subsequently use available scientific tools to attempt to address these questions. Undergraduates are exposed to a variety of techniques used in the analysis of art objects, including visible and infrared spectroscopy, gas chromatography and mass spectrometry, X-ray fluorescence spectroscopy, and microscopy. The Chemistry and Art course at Ithaca College will be discussed, and two case studies from the collaborative student research projects will be summarized. KEYWORDS: Collaborative/Cooperative Learning, Inquiry-Based/Discovery Learning, First-Year Undergraduate/General, Interdisciplinary/Multidisciplinary

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INTRODUCTION The study of intersections between chemistry, art, and art history has served as the platform for courses at a number of undergraduate institutions.1−4 Chemistry and Art, an Ithaca College general chemistry course taught in the context of art and art history, is designed to provide the basis for students to investigate, through a variety of lecture and laboratory activities, the scientific basis of such topics as paints, metalworking, dyes and fabrics, polymeric materials, and art preservation and conservation. Lectures on the material history of art help to establish the context for the study of the chemical and analytical concepts presented. Inspired largely by two Chemistry Collaborations, Workshops, and Community of Scholars workshops,5,6 the course is intended to introduce nonscience majors to basic chemical concepts and laboratory techniques, through the exploration of historical working methods such as pigment and dye syntheses, surface modification of metals, and the creation and chemistry of a fresco. The Chemistry and Art course offered at Ithaca College is unusual in that it is team-taught by a chemist and an art historian, underscoring the complementary nature of the two disciplines. The course highlights the importance of using both historical knowledge and empirical measurements to address © 2013 American Chemical Society and Division of Chemical Education, Inc.

particular questions about a work of art. Throughout the semester, introductory chemistry topics such as matter, measurement, ionic and covalent compounds, solution chemistry, atomic structure, and polymer chemistry are discussed, when possible, in the context of an artist’s working materials (colorants, binders, sculpting media, etc.). In terms of art history, topics such as the history of painting and sculpture, chronology of pigments, applications of multispectral analysis, and issues in art conservation and authentication are woven in, highlighting the impact of science on both an artist’s working methods and on the analyses of art objects. The emphasis in this course is on the alignment between the development of materials and advances in science with historical styles in artwork. A more detailed course syllabus is available in the Supporting Information. Further, a significant laboratory component exposes students to a variety of modern analytical tools and tests designed to assess the composition, age, and condition of art objects. Students learn to perform elemental analyses with a hand-held X-ray fluorescence (XRF) device, collect infrared (IR) spectroscopic data on dyes and binders, use gas chromatoPublished: October 31, 2013 1616

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Delaware.8 Objects of study have included modern and antique paintings, metalwork, a carved wood statue from Southeast Asia, porcelain ware, and a mid-20th century African mask. The project has three fundamental goals. The first goal is to have students think clearly about a question- or hypothesisdriven approach to their analysis. The second goal of the project emphasizes the relationship of art historical and chemical research to yield a meaningful outcome. The final goal is to give students the opportunity to use advanced instrumentation to define and carry out their project, connecting theory to practice in the laboratory. Given the range of objects with which the student teams work, the guidelines for the project (see the Supporting Information) highlight the question or hypothesis that is the beginning point of the investigation. This must be answerable within the means and time available. Further, students are reminded that the clearer the question or hypothesis, the clearer the structure of their investigation. To help students in this process of clarification, an initial written description of the object of investigation, as well as a preliminary framing of the question or hypothesis, is required. These statements enable the instructors to assist teams in formulating a research strategy. After objects are selected, lab time is made available for students to carry out their analysis. Students are given access to the GC−MS instrument, XRF apparatus, UV microscope, and IR camera during this time, under instructor guidance. To ensure that the objects are protected, students are supervised to ensure appropriate handling of art objects, and they have been instructed on basic ethical issues of working with cultural artifacts before this project begins. All analytical techniques must be approved in advance by the instructors, particularly if the technique involves destructive sampling. In some cases, a discovery about the object in the course of the project will change the approach that the student teams must take in their analysis. For instance, if a poorly documented object is revealed to be of greater age or potential value in the course of the project, students may be compelled to refrain from sampling or to seek additional expert opinions to help guide their work. The project outcome is a written report that details the object and its description, the problem, question, or hypothesis being investigated, and a detailed report on all tests conducted. Included in this report are test results, relevant art historical documentation consulted, and a conclusion that proposes an answer to the initial question, support or refutation of the hypothesis, or suggestions in addressing the stated problem. Results are shared with instructors through a poster that summarizes the report, and with the entire class through an oral presentation. Presentations are peer reviewed by the other members of the class. The grade is divided between the written report, the poster, and the presentation, and the team grade is assigned to all members of the team.

graphs and mass spectrometry (GC−MS) to analyze paint binding media, and use fluorescence microscopy for close observation of paint chip cross sections. The class enrollment is set at a maximum of 24 students, and student interest in the course has routinely exceeded this capacity. The student population is quite varied, representing a diverse array of majors at all levels of their college careers. The course format is an integrated lecture and laboratory, and meets twice a week for 2.5 h lecture and lab periods. These extended class periods afford the luxury of transitioning from lecture to hands-on activities with a great deal of freedom so that the course can be driven primarily by the content and not by traditional, restrictive class meetings. The course culminates in two capstone experiences. The first is a trip to the Metropolitan Museum of Art in New York City where students learn from museum scientists about the operation of the lab, the instrumentation used in the analysis of works of art, and about the collaborative relationship between laboratory staff, conservators, and museum curators. The second experience is a two-week independent research project. Working in small groups, students define questions or hypotheses about an art object provided by the Ithaca College Handwerker Gallery and subsequently use laboratory techniques, analytical instrumentation, and historical research to address these questions as best they can. Ultimately, our goal is to compel nonscientists to think analytically about a specific problem, and to draw reasonable conclusions based on the evidence they find both in the laboratory and in the library. Ideally, this project reinforces the intersections between chemistry and art, and underscores the importance of using both scientific analyses and art historical research to address questions about an art object. Each group reports their findings in a final paper and an oral presentation to the class. Herein, the research project guidelines and parameters will be discussed, and two case studies from the class will be presented to serve as examples of student work produced.

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STUDENT RESEARCH PROJECT The culminating experience for the course is a research project that combines art historical and chemical investigation. In this project, teams made up of three students examine a work of art, carry out appropriate art historical research to understand the nature of the object, define a problem for analysis, perform the analysis, and present results in posters and written papers. The objects for study have been selected from the teaching collection of the Handwerker Gallery at Ithaca College, in consultation with the gallery’s director. In a few instances, student teams obtained an object from another source after consulting with the instructors. Selection of objects is guided not only by their suitability to the analytical nature of the project, but also by concerns about the handling and sampling of the objects themselves. Fragile, valuable, or culturally significant pieces are not considered appropriate, and those who seek to reproduce this exercise are advised to use only study collection pieces, mock-ups, or similar materials for any destructive analyses. The instructors and the gallery director work with the students in the selection process to ensure that they are trained in proper handling techniques, have a respect for the potential significance of the object, and are aware of what analytical techniques may or may not be used with the object. Students are also directed to the standards documents and conservation resources from organizations such as the American Institute for Conservation,7 and the University of

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CASE STUDIES

Case Study 1: America Mourning the Death of Washington, c. 1800−1850

The work America Mourning the Death of Washington is a 14.25 in. × 10.25 in. reverse glass image of an allegorical scene commemorating the death of George Washington in 1799 (Figure 1). In the absence of documentation on the provenance of the work, the student team was encouraged to explore physical aspects of this “mystery” work that could establish the approximate date of the image, and characterize aspects of the 1617

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The student team carefully harvested two small paint chips from the edge of the painting, portions that were hidden from view in the framed presentation, for light microscopy analysis.9−11 The chips were cast in the center of a small block of polymer resin, and subsequently sanded with a circular sander until the edge of the paint chip was just exposed. Next, the edge of the chip was thoroughly polished with sand paper of increasingly fine grit (400, 600, 1200, 1800, 3600, 6000, and finally 12 000) until the surface reached a high gloss. Close observation of the cross sections of these chips under a microscope, using both visible light and UV light, revealed a resin layer between the paint and the glass support that likely served as a ground or transfer medium (Figure 3). This layer is

Figure 3. (A) Paint chip cross-section under visible light and (B) paint chip cross-section under UV light.

Figure 1. America Mourning the Death of Washington, c. 1800−1850 (14.25 in. × 10.25 in.). Collection of the Handwerker Gallery, Ithaca College, Ithaca, New York. Image used with permission.

also consistent with the yellow tint of the painting, as varnishes are known to yellow with age. A thin layer of pigment was visible on the surface of this ground layer. Finally, the students performed an analysis of the paint binder using gas chromatography and mass spectrometry. Binding media containing oils are largely composed of triglycerides. However, the native composition of an oil can vary from one plant source to another, and further, undergoes gradual changes with time. As such, the analysis of an oil’s composition can be used as a very rough measure of the age of a painting.12−14 For example, as oil paint ages, alkene functional groups (CC) in unsaturated fatty acid side chains tend to undergo oxidative cleavage to form lower molecular weight carboxylic and dicarboxylic acids. Thus, fresh linseed oil will contain a larger proportion of unsaturated fatty acid side chains, relative to saturated side chains, and virtually no measurable dicarboxylic acids. Older oil painting will contain measurably less unsaturated fatty acids and increased amounts of dicarboxylic acids, such as azeleic acid (Figure 4). The relative amounts of saturated fatty acids tend to remain constant over time, so one can compare the ratio of oleic acid to stearic acid, both 18 carbon fatty acids, in order determine a rough estimation of age of the oil. The team harvested one more chip from the edge of the painting for analysis. The paint chip was treated with commercially available “meth-prep II” reagent, a chemical cocktail containing (m-fluoromethylphenyl) trimethylammonium hydroxide, a compound designed to hydrolyze the ester linkages in triglycerides such as those present in oil-based binders, and to subsequently methylate any free organic acids to their corresponding methyl esters (Figure 5). The methyl esters of the fatty acids are much less polar than the carboxylic acids counterparts, and move more easily through a gas chromatograph column. Once the hydrolysis and methylation is complete, the reaction mixture can be safely injected into a GC−MS for analysis. In this case study, the ratio of palmitic/stearic acid present (approximately 1) was consistent with linseed oil, a common binder in oil paintings. Further, the ratio of oleic/

unusual technique. After carefully removing the painting from its frame, and closely examining the work, the students posed several initial questions to guide their subsequent research: (i) How old is the work? (ii) What is the technique and what type of medium was used? (iii) What can account for the obvious yellow tint in the work? Students used hand-held X-ray fluorescence, a nondestructive technique regularly used by art scientists and conservators to identify the constituent elements present in art objects, to analyze the paint and glass support. Without a vacuum attachment, the Bruker Tracer III−V XRF device can detect all elements more massive than silicon. Analysis of an unpainted portion of the glass at the edge of the painting revealed the presence of large amounts of lead and calcium, and lesser amounts of iron, barium, and strontium (Figure 2). As

Figure 2. XRF trace of leaded glass support for the painting America Mourning the Death of Washington.

anticipated, these elements appeared in every portion of the painting, and the results suggest that the painting was completed on leaded soda glass. Other trace elements appeared in the painted portion of the object, such as zinc. Working from the hypothesis that this painting dated from the early 19th century, based in part on the subject matter, the students found that none of the XRF results were out of character for 19th century materials. 1618

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Additional historical information was found for this image when students discovered that a nearly identical version was auctioned in 2008, indicating that the image may have been widespread.15 Numerous allegorical representations of George Washington appeared shortly after his death in 1799. However, the team’s research failed to identify the fact that this was a transfer of a print image to glass, a technique more commonly found in the mid-19th century, underscoring the notion that errors can be made in the absence of a more complete background in the material history of art. On the basis of the analyses, the materials used were consistent with an early to mid-19th century origin. The varnish layer was most likely used as part of the transfer process, and the tangible remnants of the print’s paper backing (normally peeled away from the transferred ink image) were misinterpreted as a secondary accumulation. On the basis of the art historical evidence and the scientific analyses performed, the student team was able to specifically respond to the original questions about this work. They concluded that the object was certainly more than 100 years old, and may have been created in the early to-mid 19th century. The colorants were conventional paint pigments, and the binding medium was oil, in keeping with the time period that the students established for the work. They also established that an organic varnish material interposed between the glass and the image was the likely source of the visible yellowing of colors. While the student team did not accurately identify the transfer print origin of the image, they did accurately characterize many aspects of an otherwise undocumented “mystery” object. Case Study 2: Volt, 1969; Artist, Theodore Singer

In another case study, a student team selected an undocumented large format painting from the teaching collection of the Handwerker Gallery. Volt, by artist Theodore Singer, was dated 1969, and is 66 in. × 96 in. (Figure 6). Other

Figure 4. GC trace of fresh linseed oil (top) and GC trace of linseed oil, ∼40 years old (bottom).

Figure 6. Volt, by Theodore Singer, 1969, 66 in. × 96 in. Collection of the Handwerker Gallery, Ithaca College, Ithaca, New York. Image used with permission.

documentation on media and provenance for this painting was absent. The painting had apparently been damaged while in storage and presented two immediate problems for the student team. One was to identify the painting medium. The other was to assess the surface damage and propose a hypothetical course of action for either cleaning or restoration, or both. Upon close examination of the painting, the student team observed a white, crystalline solid localized at various places on the surface. This material formed as a result of water damage

Figure 5. Basic hydrolysis and methylation of fatty acids in binder.

stearic acid (virtually zero) is consistent with a painting that is over a century old.12 1619

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art may not be sufficient to resolve all questions about the origin and nature of that work.

sustained when there was a leak in the painting storage facility. In this project, the students posed the following questions: (i) What pigments were used in this painting? (ii) What is the composition of the material formed on the surface as a result of the water damage? (iii) How might one go about cleaning the painting in a hypothetical restoration scenario? In this case, the student team learned the most about their object via the use of the hand-held XRF technique, and they analyzed over a dozen spots on the canvas. On the basis of their analyses, titanium and trace amounts of zinc were present in every test area in the painting, likely due to a ground layer containing titanium white, and perhaps due to the use of some titanium white to lighten other constituent colors. Analysis of the red paint revealed the presence of cadmium and selenium, consistent with cadmium red (CdSe), a common pigment commercially available since 1919. XRF analysis of the blue stripes on the painting revealed the presence of nickel, which indicates that nickel phthalocyanine (which exhibits a color congruent with the blue in the painting) may have been used as a component in the blue pigment. However, the analysis showed that the blue stripe also showed peaks for cadmium and selenium, indicating that the blue stripes were probably painted on top of the red. This overpainting was confirmed visually on the surface of the painting. The students were able to carefully isolate a small portion (50 mg) of the crystalline solid formed on the painting surface for testing. The students noted that the solid was fairly soluble in water, and, when mixed with a solution of silver nitrate, formed a precipitate. This evidence suggests the contaminant is a halogenated salt. Once again, XRF analysis provided more definitive evidence, indicating that the primary elements present were cadmium and chlorine. Based on its high solubility and element content, the students concluded that the salt is most likely cadmium(II) chloride. The students hypothesized, but were not able to confirm, that the cadmium chloride formed from an anion exchange between the selenide in the pigment and chloride ions present in the water that leaked onto the canvas. They used UV light to explore the surface of the painting and observed virtually no fluorescence, suggesting that the artist most likely did not apply a protective varnish layer on the surface, potentially making the painting more susceptible to water damage. The very high solubility of cadmium chloride in water suggests the best way to clean the painting would simply be to gently treat the surface with an appropriate absorbent material and distilled water. However, the team did not have time to review the available standards for such cleaning processes and thus did not assess the viability of their hypothetical scenario against other cleaning techniques. The students were unable to determine the nature of the binding medium for this painting. While the students speculated, based on the date and visual characteristics of the surface, that the paint was an acrylic polymer, they were not permitted to sample directly from the painting, and instrumentation to determine the structure of the binder in a nondestructive way was not available, so that question remained unanswered. Preliminary research did not uncover information about the artist, and the students were unable to make any meaningful comparisons to related works. The absence of documentation and the status of the painting as an unaccessioned teaching collection object limited the student team’s ability to draw solid conclusions about many aspects of this work, demonstrating that the scientific analysis of a work of

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CONCLUSION The student outcomes from this course have been quite positive, and student evaluations indicated that 100% of students agreed or strongly agreed that they learned a lot in the class. Students seem to appreciate the coordination of chemistry topics with relevant art historical material. In fact, it is this contextualizing of topics that brings reluctant students, who might otherwise not consider the study of chemistry, into the course. A few students have been sufficiently inspired by their experience in this course to pursue graduate study in art conservation. The course continues to evolve with each offeringthe current direction is to integrate more chemistry majors into the course as team leaders. As an experiment in cross-disciplinary teaching, the course has attracted considerable attention at Ithaca College. As the case studies indicate, students have an opportunity to apply creative thinking to realworld problems through the lens of chemistry and art history. This project was well received by the students, and comments on student statements reveal that they appreciated the opportunity to apply the concepts and techniques that they learned throughout the semester. Some students were uncomfortable with the open-ended nature of the project, and were disappointed that they were not able to find more concrete answers to some of the questions that they had, given the short time frame available to them. Further, by the end of the project, some groups ended up generating even more questions than they started with! However, these feelings are not uncommon in research, and experience with uncertainty can be beneficial. The successful execution of the group research projects is proof that students, regardless of their major, can acquire the fundamental tools required to actively engage in this activity over the course of only one semester.

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ASSOCIATED CONTENT

S Supporting Information *

Ithaca College Chemistry and Art course syllabus; project guidelines for the collaborative student research projects. This material is available via the Internet at http://pubs.acs.org.

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AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS We thank the National Science Foundation for their generous support of the Chemistry Collaborations, Workshops, and Community of Scholars workshop on Chemistry and Art, and the Ithaca College Educational Grant Initiative for financial support.

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REFERENCES

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(4) Uffelman, E. S. J. Chem. Educ. 2007, 84, 1617−1624 and references therein. (5) Hill, P. S.; Henchman, M. National Science Foundation Chemistry and Art Workshop, Millersville University, Millersville, PA, May 28−June 2, 2006. (6) Hill, P. S.; Norbutus, A.; LaGalante, A.; Bower, N. NSF Chemistry Collaborations, Workshops and Communities of Scholars Advanced Workshop on Chemistry in Art, Villanova University, Villanova, PA, June 2−7, 2010. (7) American Institute for Conservation of Historic and Artistic Works, Core Documents. http://www.conservation-us.org/index. cfm?fuseaction=page.viewpage&pageid=526 (accessed Oct 2013). (8) University of Delaware Library, Art Conservation Sources, http://guides.lib.udel.edu/content.php?pid=163635&sid=2016339 (accessed Oct 2013). (9) Khandekar, N. Rev. Conserv. 2003, 4, 52−64. (10) Derrick, M.; Souza, L.; Kieslich, T.; Florsheim, H.; Stulik, D. J. Am. Inst. Conserv. 1994, 33, 227−245. (11) Dredge, P.; Wuhrer, R.; Phillips, M. R. Microsc. Microanal. 2003, 9, 139−143. (12) Colombini, M. P.; Modugno, F.; Fuoco, R.; Tognazzi, A. Microchem. J. 2002, 73, 175−185, DOI: 10.1016/S0026-265X(02) 00062-0. (13) Blasko, J.; Kubinec, R.; Husova, B.; Prikryl, P.; Pacakova, V.; Stulik, K.; Hradilova, J. J. Sep. Sci. 2008, 31, 1067−1073, DOI: 10.1002/jssc.200700449. (14) Mills, J. S.; White, R. The Organic Chemistry of Museum Objects, 2nd ed.; Butterworth-Heinemann: London, 1994. (15) Cowan’s Auctions, Cincinnati, OH, October 17 and 18, 2008. Documented at http://www.cowanauctions.com/auctions/item. aspx?ItemId=63950 (accessed Oct 2013).

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