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The Charters of Freedom

Created date

June 18th, 2009

This cross section diagram shows the various components that make up the new encasements. (Graphic by Ray Ruskin) In the last week, I've received several emails from readers inquiring about the Charters of Freedom story running in the Tribune's June issue. In 2003, the National Archives embarked on a massive restoration effort that included repairing minor signs of wear on the Declaration of Independence, the Bill of Rights, and the Constitution, then reencasing the documents in state-of-the-art containers. While the main article contains a detailed description of the encasements themselves, sometimes words alone cannot compete with the visual specificity of a good diagram. I think this is one of those instances, which is why I'm including a cross-section graphic of the different components that make up the new encasements. The construction of these containers was a feat of scientific collaboration in which the fields of conservation, engineer, optics, and metallurgy came together to produce cases that will enable the Charters to outlast anyone alive today. Each parchment's encasement consists of an aluminum base, covered with a 3/8-inch-thick piece of high-grade, non-reflective glass, bolted and gasketed to a frame of commercially pure, gold-plated titanium. Conservators assembling one of the new encasements. Once sealed, these containers are filled with inert argon gas to create and maintain a stable environment that should preserve the Charters for centuries. (Photo courtesy of the National Archives and Records Administration) The parchment rests on an aluminum platform covered in a special paper that absorbs and releases moisture. After sealing the encasements, conservators fill them with inert argon gas that provides a constant level of humidity. As noted in the diagram, designers have also included small compartments beneath the document platform that house optical monitoring devices, which conservators can use to track the humidity, temperature, and oxygen levels within each encasement. These levels should remain around 40% relative humidity at 67 degrees Fahrenheit. And though National Archives represenatives decline to discuss the various security measures employed to protect the Charters, they assure us that the precious documents are quite safe.