By Bruce Schundler

a report on the thesis of
Elizabeth Moss, Master of Science
University of Pennsylvania (1998)

Archaeological "digs" by their very nature can be very destructive. The work of archaeological conservators is "to minimize damage that is inherent in the archaeological process without jeopardizing the investigative goals of the archaeologist."

A Typical Archaeological Site

Elizabeth Moss, working with Professor Frank G. Matero of the University of Pennsylvania, wrote her thesis on the use of perlite and vermiculite to conserve certain sites during excavation.(see Database Library of the University of Pennsylvania / Elizabeth Moss )

Essentially the problem she researched and tried to resolve was how to preserve old plastered walls and mud bricks which began to decay and deteriorate almost immediately upon exposure. After extensive testing, she found a mixture of 75% very fine perlite (cryogenic grade) and 25% super fine vermiculite offered the best option. The fine perlite could absorbed up to 959.39% moisture as compared to 594.22% for very fine vermiculite (this comparies to regular soil which absorbed only 74.27%.) After a specified "drying" time, the perlite held less moisture (3.45%) than the vermiculite (44.22%). And so a mixture of both seemed to be the best combination.

This perlite and vermiculite mixture was placed in a geotextile "bag" which was then placed up against the fragile exposed walls whenever excavations were suspended or stopped. With the proper application of moisture and pressure, Elizabeth Moss was able to demonstrate how simulated plastered walls could be preserved and protected. In essence, she proved that these fragile walls can be preserved, and therefore should be preserved by those excavating sensitive, archaeological sites.

Recently we spoke with Dr. Frank Matero who reported that this basic approach was tested and used both in Turkey and at Mesa Verde National Park in the United States. The results were amazing---and we eagerly await another report and some pictures!

For a much more thorough reading of her thesis and work, please go to the link above and download her thesis.

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