Using Mobile Spectroscopic Instruments to Characterize Historic Fabrics

Mobile spectroscopic instrumentation, using techniques such as Raman spectroscopy, X-ray fluorescence spectrometry (XRF), Fourier transform infrared spectroscopy (FT-IR), and laser-induced breakdown spectroscopy (LIBS), has been applied in archaeometry research. Mobile spectroscopic techniques are proving useful, as nondestructive methods for examining components of cultural heritage objects-such as fibers, pigments, dyes, and inks-for quantitative and qualitative results. Mary Kate Donais of Saint Anselm College, in Manchester, New Hampshire, uses mobile instruments in analytical archaeometry studies, and has conducted a recent study on the spectroscopic characterization of historic fabrics from a turn-of-the-19^th century New England mill belonging to the Amoskeag Manufacturing Company, also in Manchester, and one of the largest textile producers in the world at its prime. We recently spoke to Donais about this work.

You have written a review on the growing importance of mobile spectroscopic instrumentation in archaeometry research (1). How did you become interested in this field?

I was approached by David George, a professor of classics on our campus, to collaborate on a laboratory experience for his course in classical archaeology. This project led to my participation at our college’s field archaeology school in Italy. Portable instrumentation fits well within field work, especially in archaeology, when removal of samples is challenging. I’ve been using portable spectroscopy ever since.

How did the specific opportunity to examine these century-old fabric samples come about?

I attended an exhibit opening featuring locally made quilts at our local history museum. I spoke to the co-curator on the exhibit about our work with cultural heritage and portable spectroscopy, and she was intrigued. The museum’s director overhead our conversation, and mentioned the fabric sample books in the museum’s collections. We were all hooked!

What was the goal of this particular examination, and in general the study of other cultural heritage objects?

Having access to both the handwritten dye recipes and the corresponding fabrics was a perfect coming together of history and chemistry. The first part of the project involved a history student examining the recipes, and doing the archival research to make some sense of them from a historic perspective. The next step was to examine the fabrics using spectroscopy to try to connect the chemical information to the written word. The terms used for dye production at the turn of the century are not those used today. So, verifying things through spectral information was our main goal. In general, my goal for any study of cultural heritage objects is to learn more about the object, and the people associated with the object, through its chemistry.

Did you go into the process with any hypotheses about what you would discover with these samples? What did you actually discover?

Having no previous experience with fabric dyes and fabric production processes, we really had no specific hypotheses about the samples. We are confident in our ability to collect spectroscopic information, so we thought we could learn at least a little bit about the dye chemistry.

Were there any potential challenges or concerns with using Raman spectroscopy in the examination? How did you develop the analytical and sampling techniques that you used?

Raman can damage more delicate materials, including natural fibers, if the laser power is too high. So, yes, we were concerned about using Raman to examine the fabrics. We were able to find some fabric scraps from the same time period to explore different instrument settings, and to make sure we didn’t cause any burn holes. As it turned out, however, we were not able to detect any Raman signal for the dyes. This is likely due to their low concentrations. Portable XRF was much easier to use, and produced much more encouraging results. The biggest challenge with the XRF was its instrument window size, which allowed us to only examine certain fabrics with larger single-dye areas in the patterns.

What conclusions were you able to draw from these findings?

We have identified some specific fabric colors that have similar elemental profiles.  

What are your next steps in this work?

We need to follow up with a more careful examination of the dye recipes, and spend more time trying to link the spectroscopic information to the turn of the century terms and documented dye processes. Also, we had some success with FT-IR microscopic analysis of a few of the dyes. While not a portable technique, the results are encouraging, and worth further efforts.

You have also studied pigments found on fresco at various sites in Italy (2), as well as Roman glass studies (3). How did the challenge of these Raman studies differ from the New England study?

Each different sample type has given our research team the opportunity to learn about a new cultural heritage material, and how best to approach its characterization. Each has had its own unique challenges. The fresco data were collected in a field laboratory, which had a lower level of control compared to a typical science laboratory. To better understand the Roman glasses, we needed access to instrumentation such as a micro-Raman spectrometer not available in our college’s laboratories. Collaboration with Peter Vandenabeele’s group at Gent University solved that situation.

References

• P. Vandenabeele and M.K. Donais, Appl. Spectrosc. 70(1), 27–41 (2016).

• M.K. Donais, D. George, B. Duncan, S.M Wojtas, A.M and Daigle, Anal. Methods 3(5), 1061–1071 (2011).

• M.K. Donais, J. Van Pevenage, A. Sparks, M. Redente, D.B. George, L. Moens, L. Vincze, and P. Vandenabeele, Appl. Phys. A122(12) 1050 (2016).

Mary Kate Donais earned her BS in Chemistry from Bucknell University and PhD in Analytical Chemistry from

the University of Massachusetts, Amherst. Following positions in both a federal lab and industry, she joined the faculty at Saint Anselm College in 1999, where she is currently a professor in the Chemistry Department. Dr. Donais’ research is focused in spectroscopy and portable instrumentation, especially applications in the fields of archaeology and cultural heritage analysis. Her scholarship efforts include 17 peer-reviewed journal articles, numerous conference presentations, one book chapter, and one co-authored book. The vast majority of this research was conducted by the 35 undergraduate students she has advised in her 20+ years in academics. She is actively involved with the Society for Applied Spectroscopy (SAS), the Federation of Analytical Chemistry and Spectroscopy Societies, and the Society for Archaeological Sciences. Dr. Donais is a fellow of the SAS and the Royal Society of Chemistry. She is currently serving as Program Chair for the 2020 SciX Conference in Sparks, Nevada.