The Map Today
The Library of Congress is protecting and preserving the Abel Buell 1784 map of the United States by placing it in a state-of-the-art case with stringent environmental controls that have been determined by preservation experts.
Why is Preservation Important?
Preservation of our cultural heritage through controlling the environment is critical to ensure it is around for future generations.
What if the map got too much light?
Too much light causes damage by fading inks and light sensitive colors on the map.
What if the map got too much oxygen?
Too much oxygen can degrade paper, breaking down the chemical bonds and making it brittle.
Measuring the Map’s Current Condition
To determine how best to protect the map we need to assess its current condition. Using non-invasive techniques, conservation scientists analyze and characterize the map.
Hyperspectral Imaging Hotspots
Image processing indicates two different inks being used (even though they both look the same in visible light).
False color imaging enhances the range of colors that have faded on the map.
The response of the map to the visible and non-visible light spectrum allow us to identify the pigment without sampling.
Special processing allows us to reconstruct what the original printing plate looked like.
Hyperspectral Imaging
Hyperspectral imaging non-invasively captures images in the visible and non-visible spectrum of light to uncover hidden text and information, identify colorants without sampling, and create baseline data that allows us to track changes due to the environment.
X-Ray Fluorescence Hotspots
This discolored region of the paper has more copper than in other areas of the paper. This suggests that the discoloration may be faded verdigris (the copper containing colorant).
The yellow suggests the presence of an unidentified organic (plant) colorant. Copper present in the yellow indicates the colors may have been mixed.
The green in the cartouche is consistent with a copper- containing pigment, possibly verdigris.
This ink is consistent with bone black, indicating a carbon based ink. Many historic inks were iron gall ink.
X-Ray Fluorescence
X-Ray Fluorescence Spectroscopy allows us to look at the inorganic elements (metals) present in materials and is another non-invasive technique used to identify material composition. Identification allows us to know how to preserve the map while on view.
Microfadeometer Hotspots
Durable.
The carbon ink is resistant to change due to light and not
likely to fade.
Moderately Light Sensitive.
The background paper is moderately light sensitive and not as
reactive to light.
Very Light Sensitive.
The green color is very light sensitive and
likely to fade with too much light.
Very Light Sensitive.
The yellow color is very light sensitive and
likely to fade with too much light.
Microfadeometer
The micro-fade spectrometer is a portable instrument that allows us to take light-fastness measurements on the map to identify colorants that are more sensitive to light. This information aids in predicting safe light levels and preventing damage to light-sensitive colorants from exposure.
How is the Map Being Protected?
To ensure the longevity of the map all care is being taken through controlling all aspects of the environment while it is on long-term exhibition.
An anoxic encasement controls the internal environment around the map by removing any oxygen that can harm materials, and controlling the level of moisture content. Library staff track and monitor what is happening to the environment inside and around the case at all times.
Map in Anoxic Encasement Hotspots
The encasement is transported on a specially constructed cart.
Hidden under the frame, a double viton o-ring ensures the case can hold a hermetic seal and protect the map.
The frame of the map is secured to the encasement base. The map is now ready for the rest of the encasement to be constructed.
The hurricane proof glass is lifted onto the base.
The frame is placed over the 600lbs of glass to secure it.
Tightening the 48 bolts holding the frame and hurricane proof glass to the base.
Sensors attached to the encasement track real-time data to ensure performance and control the environment.
