Who would have thought that shining a few lights on a national monument would cause such a problem? But in the course of things, lights attract gnat-like flies called midges, and the food chain takes over from there. Spiders come to eat the midges; birds come to eat the spiders. And in Washington, D. C., famous for its cherry trees, those same birds eat a lot of cherries. In the end, the birds leave a colorful mess.
But removing the stains on the monument is not a simple matter of hosing them down each day. In fact, water weakens stone and actually speeds up deterioration.
Figuring out how to clean the aging Lincoln Memorial and Jefferson Memorial, however, was only one piece of the puzzle the National Park Service faced when they set out to spruce up the monuments a few years ago. Other problems included missing stones, hairline cracks, and weathering in general.
Faced with what was becoming a massive, multiyear project to preserve and rehabilitate the memorials, the National Park Service called on Penn's Architectural Conservation Laboratory for help. The result is a cooperative agreement between the lab and the park service.
"We've become partners in pursuing research and training activities
in the field of architectural conservation," says Frank G. Matero,
director of the Architectural Conservation Laboratory, which is part of
the Graduate Program in Historic Preservation in the Graduate School of
Fine Arts. Matero explains that the collaboration, now in its fourth
year, is "a great coup for Penn," because the park service "provides
world-class sites and funding for projects like this one. It also
provides an opportunity for students to get excellent field training and
sponsored theses in 'real' projects." Matero is director of the
Washington project and principal investigator at Penn.
Assessing the technical publications
Since March, Matero, three GSFA students (John Carr, Robert
Hartzler, and Dawn Melbourne), and one post-graduate (Jean Wolf) have
been working to develop a comprehensive treatment program to halt the
deterioration of the two monuments. The first phase of the project,
which is about 98 percent complete, is an assessment of the technical
publications on American limestone and marble-in particular the kind
used in the Jefferson and Lincoln Memorials.
Because the marble used in the Lincoln and Jefferson Monuments comes from quarries in Danby, Vermont, and Yule, Colorado, the project, Matero says, has been "very targeted for North American building stone and marble." One of the group's missions was to find out what other stone conservators have tried with these particular stones. Most of the literature on stone conservation, Matero continues, "has a European bias-and for good reason, given the long tradition there."
According to Carr, "The first phase has permitted us to critically
evaluate a lot of the literature out there . . . and to understand what
is there and what holes are there." Perhaps the most significant gap is
that there is very little written work on North American stone. "The
information we thought would have been there in abundance is not there,"
explains Melbourne. Even though stone has received more attention than
any other material, little has actually been written on the laboratory
work or case studies. Melbourne believes that "People are not willing to
put their reputations on the line: `Hey, I tried this, and it didn't
work.'"
Using the resources at Penn
During the first phase of the project, the group was able to carry
out the bibliographic research using the computer resources of Penn's
library system. "We can do this at Penn," Matero says, "because of the
remarkable electronic library and the interlibrary loan system. The Fine
Arts Library here is phenomenal." Wolf agrees, adding that the
interlibrary loan staff "has been terribly cooperative and helpful."
Also invaluable were the University's conservation holdings and the
laboratory facilities of the Graduate School of Fine Arts, which Matero
says are "at the top of the list."
For each article the team located, they recorded basic bibliographic information and wrote an abstract. They also considered several specific questions: Is the stone discussed similar to that used in the Lincoln and Jefferson Memorials? Is the "treatment history" well documented? Is the stone in an environment similar to that surrounding the memorials? From this information, a database is being created to assess the literature and the research trends.
One problem the group has encountered is that there appear to be no consistent research standards. "There is not one international standard-methods vary-so we must know the standards of various countries," says Wolf.
Surprisingly, the researchers also discovered a lack of follow-up
in conservation treatment. It often seems that once a stone is treated,
it is forgotten, which is why, Melbourne says, this project has been
valuable. "It is a good opportunity to do something that is not done
often enough-assessing past treatments" and making critical evaluations
of the conservation work.
Analyzing similar sites
On the basis of their research, Matero and his group have been able
to identify eight sites that are comparable to the Jefferson and Lincoln
monuments in Washington. These sites have similar stone- and similar
symptoms of deterioration. In addition, the eight sites have also been
treated for their symptoms, and good treatment records exist.
It will be Melbourne's job to evaluate what worked and what did not work at those comparable sites. From that, it will be easier to determine what treatments might work best to conserve and rehabilitate the Lincoln and Jefferson Memorials.
"It's an opportunity to learn from past mistakes and benefit from the things we've done correctly," says Melbourne. The project is also providing an important opportunity for Melbourne, who is working toward the newly established Certificate in Architectural Conservation, the step beyond the master's degree in historic preservation.
Now that they have discovered the limits of the available research, the next step for Matero and his team is to develop a program to test varieties of marble from Danby and Yule. And that is what will begin next year when the Architectural Conservation Laboratory will be packed full with chunks of stone. As Matero explains, large blocks of stone were found in builder's trenches near the Jefferson and Lincoln monuments. "It's a great find, because otherwise we would have to go back to the quarry," he says, "but that stone hasn't been sitting in Washington, D. C., for 70 or so years." According to Matero, the National Park Service will probably begin doing actual work on the monuments around the Year 2000.