"The stitches [from the backing] obscured a lot of damage to the flag. This caused us to make decisions in how we would conserve the flag," Zoidis said.
One of those decisions was that the flag could no longer hang vertically in the museum's Flag Hall.
Then there was the delicate matter of cleaning the deteriorated wool fibers.
In 1999 conservators began examining the flag in a lab, built in the museum so visitors could watch the preservation work.
The scientists used digital imaging systems to inspect the wool fibers up close.
William Marmer, a researcher for the U.S. Department of Agriculture (USDA), was part of the team involved in the analysis of the wool fibers and fabric.
"Jeanette Cardamone [of the USDA] used digital-image analysis to determine fault areas to the weave," Marmer said.
"During the analysis of the fibers, Alberto Nuñez of the USDA lab found environmental contaminants and residues like nicotine."
Two wool researchers from New Zealand also worked with the USDA to study how ultraviolet light had degraded the wool. The experts concluded that most of the damage from light had likely occurred in the early days of the flag's history.
While Marmer's team provided a detailed look at the fibers, conservators also had to consider the structure of wool itself. Wool is a natural polymer, which means it's composed of different layers.
"Wool is an amazing fiber," said Len Buckley, a chemist with the Naval Research Laboratory in Washington, D.C.
"If you take a cross section of wool, you will see different structures. These different levels of structure are the cause of the many wonderful properties of wool."
Examining a cross section of one of the flag's wool fibers through a scanning electron microscope, Buckley could see damage and residue to the "scales" on the outer layer.
"The question is whether or not to remove [the residue]. You could clean the wool with solvents, and then run the risk of damaging the fibers," Buckley said.
New Future for the Flag
After receiving recommendations from scientists and wool experts, the project's chief conservator, Suzanne Thomassen-Krauss, made the decision to clean the flag in two phases.
The first effort, begun in the summer of 2001, involved cleaning both sides of the flag with dry cosmetic sponges. Using as many as 5,600 sponges for one cleaning, conservators painstakingly went over both sides of the flag two times.
The next phase, conducted from October 2003 to January 2004, called for a mixture of acetone—the active ingredient in nail-polish remover—and water to be carefully brushed onto the flag.
"The tests [from researchers] showed that if we didn't clean [it], the flag would be in more jeopardy than if we cleaned the flag," Zoidis said.
Finally, in spring 2004, the team attached a new lightweight material called Stabiltex at points where the flag was most fragile. This new backing is much less invasive than the 1914 linen backing and can be easily removed.
With the Star-Spangled Banner cleaned and prepped, conservators have now set their sights on the final phase of the project: building the space that will house the flag.
To keep stress on the old flag to a minimum, the new facility will be a clean-room environment, with temperature and humidity controls, low light levels, and a state-of-the-art security system.
The display is slated to be unveiled to the public in July 2008, when the museum will reopen after a major renovation scheduled to begin this September.
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