Inside the three-layer case, a glass middle sits right on top of the page. It's all sealed in a bronze frame soldered with lead and filled with helium. It looked like a permanent solution 50 years ago. But it wasn't.
Mark Ormsby of the National Archives has been comparing pictures of spots on the documents today to older pictures of the same spots. He feeds the images into a computer to compare them and is finding dramatic differences.
Not only is the glass breaking down, but the camera has also spotted one patch in the constitution where the ink has come off. "We're able to see the ink is lifted off from the surface at that area," Ormsby says.
Those discoveries have spurred a quest to build new, super-protective cases. The mission was handed to the National Institute of Standards and Technology, the government's high-precision laboratory.
The case needed to be airtight, but unlike the present system, there needed to be a way to get inside.
The team succeeded in building an impressive test model. Turn a few bolts, and the case opens so the papers can be examined and the glass replaced.
The documents rest on a platform, and nothing touches them but small plastic retaining clips. The engineers will run a series of torture tests on the prototype. Then they will start building nine cases for the archives display.
After spending $5 million and using every high-tech idea they could find, they hope they build a case as enduring as the documents it will hold.