After the team removed the backing, they began cleaning debris from the flag. First, they dabbed dry cosmetic sponges on its surface, working their way inch by inch across the 1,020 square feet of material, all while lying stomach-down on a platform that hovered inches above the fabric. Next, they used a solution of water and acetone to remove surface deposits of oils. The flag was then sewn to a sheer high-tech polyester material called Stabiltex to give it support. Finally, the side of the flag that had been on display for decades was attached to a custom-made laminate underlay traditionally used for racing-yacht sails; what visitors view now in the gallery is a side of the flag that had not been seen by the public since 1873, when the flag hung from a window at the Boston Navy Yard and was photographed for the first time.

The flag’s display chamber is a marvel in preservation precautions. The long corridor leading to the exhibit hall gets progressively darker so visitors’ eyes can adjust to the two-story room’s dim light, which is provided by a single projected slide. Instead of a single point of light, which can cause hot spots and shadows, the projected slide is a patchwork of several hundred pixels in different shades of gray. The resulting light is equivalent to that of a candle being held at a distance of one foot. The sealed display case is kept at between 68 and 72 degrees Fahrenheit and at between 50 and 70 percent humidity, conditions that allow the fragile fibers to remain flexible in case conservators should ever need to roll the flag up. The oxygen level is kept at 15 percent, which serves both as a fire-safety precaution and hopefully, as a preservation technique, slowing deterioration. The flag is tilted at a slight angle so that visitors can adequately see it and so that the integrity of the fabric is not compromised.

What museumgoers see now -- the result of eight years of meticulous work -- is the perfect balance of preservation and presentation. “[The flag] is resting -- not under stress, not subject to things that can cause damage,” Thomassen-Krauss says. “But it’s still wonderfully accessible to anyone who wants to see it.”

The eight-year process has been an often-emotional experience for Thomassen- Krauss, who first pondered the problem of preserving the Star-Spangled Banner as a graduate student in 1978 after hearing a lecture from a Smithsonian conservator. She knows the work she’s done means a great deal to many people. The day after the exhibit opened, she walked into the gallery and found a young woman crying. The woman’s grandmother had once worked at the museum and had told her about the ongoing conundrum of what to do with the flag.

“She said that her grandmother would be so happy now,” Thomassen-Krauss recalls. “You realize you’re never doing this for yourself. You’re doing it for everybody else.”