In 1987 the NARA installed a $3 million camera and computerized monitoring system. It was designed by the Jet Propulsion Laboratory to monitor the condition of the Charters of Freedom.
The system warns archivists about changes in readability due to ink flaking, changes in document dimensions, or fading. It's capable of photographing one-inch square areas of the documents and retaking the pictures periodically to make sure that nothing has changed.
People are also reading…
Measurements are compared to a baseline image to detect changes not visible to the human eye. Because the ink on the Declaration has faded badly, tourists aren’t allowed to photograph the light-sensitive document, Kleiman says. The glass filters out damaging ultraviolet light.
Inside the case that holds the Declaration, "they have created a microclimate that is without oxygen," said Laura Moeller, owner of Strange Stock Art Conservation in Alameda, CA, "They believe the absence of oxygen is the best thing for that piece. "
Oxygen and humidity are the enemies when it comes to preserving parchment, Moeller explains. Even the moisture from human breath could damage the document over time, she notes.
