January 04, 2018

Catholic University’s Vitreous State Laboratory (VSL), together with the Library of Congress and George Washington University, has been awarded a three-year $350,000 grant from the National Endowment for the Humanities (NEH) for a research project aimed at improving preservation methods for priceless glass flutes known around the world for their beauty and intricacy.

As part of the project, VSL researchers are examining 18 glass flutes dating back to 1804. Housed within the Library of Congress’s Dayton C. Miller Collection, the flutes were fabricated by the noted Parisian artisan Claude Laurent. Only about 140 flutes made by Laurent exist around the world today, but they were once presented as luxury items to emperors, kings, and even to President James Madison. Many collectors are also bringing their instruments to be assessed and included in this study.

The award recognizes the important progress that has already been made by VSL scientists Isabelle Muller and Rev. Andrew Buechele, who began researching the collection in 2014, after Library of Congress archivists approached VSL Director Ian Pegg and asked if the laboratory could help in understanding what was causing patches of foggy deterioration on several of the flutes.

With permission and under close scrutiny of Library of Congress personnel, Father Buechele obtained microscopic chips of glass from two of the instruments in the collection that exhibited signs of severe deterioration. The chips were analyzed at VSL using scanning electron microscopy and other methods. Though the flutes historically were described in an 1806 patent as being made of “crystal,” or leaded glass, the chips Father Buechele obtained were actually made of potash glass containing rather high levels of potassium.

“Leaded crystal glasses are generally pretty resistant to attack by water, but these high potassium glasses are not,” he said. “Over time, the flutes have been attacked by atmospheric moisture.”

According to Muller, the foggy appearance on the flutes develops when water from humidity in the atmosphere or the breath of the flautist enters the glass and reacts with potassium causing it to leach out of the glass. The chemical interaction leads to a hydration of the glass structure, leaving it susceptible to expansion and contraction with cyclic humidity changes. The resulting mechanical stresses initiate fine surface cracking, which gradually progresses in depth over time. The process is referred to as “crizzling” and it creates a roughened surface and cloudy appearance. If allowed to continue, the interactions will result in greater damage to the priceless flutes.

Thanks to the VSL research, archivists at the Library of Congress have already taken steps to improve their storage facilities, using precise humidity levels believed to be best for the health of the flutes. Under the coordination of Murray Loew, an imaging and optical spectroscopy specialist at George Washington University, the new award will support further research on understanding the mechanisms and processes of degradation and their variations with glass composition and storage environment. The findings could also be helpful in preserving other glass heritage objects of artistic and historical merit.

Elizabeth Montagnino, a junior chemistry major from Severna Park, Md., has been working with VSL since last summer in a paid position funded by the grant. As part of her research work, Montagnino has been fabricating glass samples in the same range of compositions found in the flutes. By testing the lab-fabricated glass samples in environmental chambers that simulate aging, she and the team hope to learn more about how the aging process works.

“We can simulate 200 years of natural aging in a day’s lab,” Muller said. “We want to see the relative impact of a given kind of aging as related to the content of potassium and lead in the glass.”

For Montagnino, the project is a valuable learning opportunity. In addition to working in the lab, she has been able to visit the Library of Congress archives to learn about the preservation process in person.

“This definitely isn’t something I was expecting to be a part of so early in my education,” Montagnino said. “The materials I work with here, the equipment I work with; most of the time you don’t get to use it until you’re at the graduate level.”