Smithsonian's Museum Conservation Institute Research Experiences for Undergraduates in Archaeological and Museum Conservation Science
2012 Project Summaries
Project Title: Advanced imaging for daguerreotypes
Intern: Allison Rabent, Rochester Institute of Technology
Advisors: Melvin Wachowiak and Edward Vicenzi
This project focused on using advanced imaging to examine the condition of historic daguerreotypes. One of the earliest forms of photography, daguerreotypes were made using polished plates of silver-coated copper and were housed in small cases for protection. Many daguerreotypes found today suffer from the effects of corrosion, biological growth, and damage from past cleaning or re-housing. This project utilized photography, axial specular photography, brightfield microscopy, high magnification mosaic imaging, SEM/EDS and Raman analysis, and other techniques to study and document the daguerreotype surface. The information obtained can now be used for the care and conservation of daguerreotypes in both private and museum collections.
Project Title: Sample re-use between micro X-Ray diffraction and Fourier Transform Infrared Spectroscopy
Intern: Emily Rundlet, Colgate University
Advisors: Jennifer Giaccai and Nicole Little
Because MCI routinely works with subject matter that is rare, delicate, and/or valuable, often only a very small amount of sample is provided for analysis. For this reason, sample re-use is a common tactic in non-destructive instrumental analysis. This project used standard artists' materials to analyze whether or not a sample can be confidently re-used between micro X-ray diffraction (XRD) and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) without compromising the results of either instrument. One concern is the alteration of XRD results due to the pressure applied during ATR-FTIR and potential subsequent damage to the crystal structure. Another cause for concern is that traces of the adhesive used to mount the sample during XRD could potentially appear on the IR spectrum. Results show that one type of adhesive, high-vacuum silicon grease, does appear on the FTIR spectra of all samples tested, while the others do not (rubber cement and school glue). Further results suggest that the pressure used when undertaking ATR-FTIR can have an effect, sometimes negative but more often positive, on the crystallinity of the sample and hence the XRD spectrum.
Project Title: Dating proteinaceous museum specimens
Intern: Christopher Rollman, Towson University
Advisors: Mehdi Moini
This project focused on dating proteinaceous museum specimens using amino acid racemization mass spectrometry techniques. Using an in-house developed technique combining capillary electrophoresis and mass spectrometry, one can separate isomers of amino acids and compare their relative ratio. When proteins are synthesized, they are wholly comprised of L-isomer amino acids which convert to the D-isomer over time. By comparing the ratio of the two isomers, we can effectively determine the age of silk specimens. During this research, specimens of silk with known ages were analyzed for their isomer ratios and a calibration curve was created correlating age to ratio. This calibration curve can now be used to indentify unknown ages of other silk specimens. Further preliminary research included identifying common contaminants of silk, applying the technique to bone collagen, and studying factors which affect the conversion between isomers.
Project Title: Biological Clocks: High-throughput identification of deterioration markers in collagen
Intern: Raquel Fleskes, University of Maryland
Advisors: Mehdi Moini and Christine France
The solubilization, separation, and analysis of collagen in bone are new and upcoming foci of study in the field of proteomics. The novelty of this endeavor is hampered by collagen’s poor solubility, showing the importance in developing an effective method of sample preparation in order to analyze possible biomarkers in collagen. This project focused on developing techniques to solubilize collagen for capillary electrophoresis mass spectrometry. Once completed, future research in deamidation and truncation can be analyzed to create a calibration curve to potentially accurately date ancient human bone remains.
Project Title: Using Raman spectroscopy to distinguish and calibrate collagen preservation for IRMS analysis
Intern: Charlotte Doney, George Washington University
Advisors: Odile Madden and Christine France
Isotope ratio mass spectrometry (IRMS) is used routinely in archaeology and paleontology to understand population diet and habitat from the carbon and nitrogen isotopes of intact collagen, the structural protein of bones and teeth. Fourier-transform Raman spectroscopy (FT-Raman) has the potential to non-invasively determine the quality of this collagen before undertaking the rigorous chemistry required to extract it from the bones for IRMS analysis. Raman spectra were collected from bone, teeth, and extracted collagen that had been determined previously to have “good” or “compromised” collagen quality indicators. The remains used for the analysis range from modern mammal bones, 100 hundred year old human remains, to fossilized North American megafauna. Results suggest that FT-Raman can be used to detect whether collagen in animal bones and teeth is compromised and potentially can be used to determine the state of preservation of bone found in an archaeological or paleontological setting prior to selection for study by IRMS.
Project Title: Using stable isotope mass spectrometry to establish the provenance of human remains from Antebellum United States
Intern: Danielle Dunn, George Mason University
Advisors: Christine France
This research established stable isotopic indicators of demography and origin within the United States by comparing data collected from human remains recovered from the site of the Battle of Glorieta Pass, NM; Ft. Craig, NM; and Pettus, VA population sets in Antebellum United States. Remains of known racial identity reclaimed from these battles were compared to known areas of muster. Further comparisons of these remains were made to those from a Virginia plantation slave population, and finally both data sets were correlated with historical records of diets for each population set in Antebellum United States. Human stable isotopic values within bones and teeth are incorporated directly from diet. Using historic dietary records with previously determined isotopic maps of the United States allows one to correlate isotopic indicators to race, social status, and provenance of reclaimed individuals.
Project Title: Pathways to research: the importance of making a spectral library
Intern: Hannah Tubb, Grove City College
Advisors: Odile Madden
All too often polymer composite materials, commonly called “plastic”, are described solely by the base polymer. However, material properties also are tied to plasticizers and other components. Accurate characterization of “plastic” requires multi-component search strategies. This is especially critical in the museum context, where the challenge often is to identify and diagnose deteriorating artifacts of unknown composition spanning two centuries of evolving technology. Raman is a non-destructive tool that distinguishes the constituent compounds, but relies on comprehensive spectral libraries and innovative approaches to reverse engineer mixtures. In response to this need, 100 polymer and 90 plasticizer reference materials were analyzed using Fourier transform and dispersive Raman spectroscopies. These spectra form the basis of a searchable reference library of 19th-21st century materials. In keeping with the Smithsonian mission to increase and diffuse knowledge, these spectra will be made freely downloadable on the Smithsonian Institution website (www.si.edu).
Project Title: Comparison of microchemical tests and GC-MS in dye analysis
Intern: Leah Poole, Hillsdale College
Advisors: Jennifer Giaccai
This project aimed to determine the best method to analyze and identify dyes used on historical objects. In order to preserve as much of the object as possible, the preferred method would have the lowest limit of detection. Gas chromatography-mass spectrometry (GC-MS), pyrolysis GC-MS, and Fourier transform infrared microscopy (µFTIR) were used, and the resulting chromatograms and spectra were analyzed. Throughout the process, different methods of extraction were tested on both natural and synthetic dyed wool samples to determine which technique would provide the most effective dye extraction. None of the tested methods have provided a straightforward and sample-efficient method of detection for all the dyestuffs tested, but results were obtained for identifying some natural dyes with GC-MS, some synthetic dyes with Py-GC-MS and developing a method for use with µFTIR of extracted samples.
Project Title: The unknown truth about paints
Intern: Anastasia Lewis, Rochester Institute of Technology
Advisors: Jennifer Giaccai
The mixture of paint in a piece of artwork is important to conservators because different paints react differently and can change the conservation of the paintings. Alkyd paints have a reduced drying time but are very brittle, while oil paints can take months, even years to dry. Acrylic paints are known for their high resistance to chemicals, flexibility, and stability under prolonged thermal stress. For this project, several paint samples (n=162) were prepared using mixtures of alkyd, oil, and acrylic paints. The techniques for the mixtures were ratios ranging from 10-90% of each component. Samples were analyzed using three different GC-MS techniques to find the best method for GC analysis. These methods will be incorporated into future analyses of paints to assist in formulating conservation plans.