The Science of Preservation

(The following is a story written by Jennifer Gavin for the January/February 2015 issue of the Library of Congress Magazine, LCM. You can read the issue in its entirety here.)

Preservation specialist Michele Youket assesses CD damage through a microscope known as an Axio Imager. Photo by Amanda Reynolds.

Preservation specialist Michele Youket assesses CD damage through a microscope known as an Axio Imager. Photo by Amanda Reynolds.

Scientific research in its laboratories helps the Library to preserve and display world treasures.

Books with cracked leather bindings; crumbling, yellowed maps and newspapers; faded photos; delaminating audio tapes. Most of us have seen what time can do to the media of the moment, when that moment is years, decades or even centuries past.

Preventing such damage is a significant issue for the Library of Congress, which holds millions of books, maps, photos, illustrations and manuscripts in many formats–and preserves them for future use, even if they are also digitized. While many Library divisions have a hand in the maintenance, preservation or recordation of these original materials, the Preservation Directorate is at the heart of the effort. Its expert staff brings science to the task of preserving a given item by keeping it stable, and thereby available for future users; ensuring that the Library’s handling doesn’t hurt it; and finding out what secrets an object may hold.

The Mission: Keep It Usable

The Preservation Directorate’s mission is to assure long-term uninterrupted access to the intellectual content of the Library’s collections. Materials to be preserved range from parchment and paper to glass, fabrics, ceramics, photographs and metals, as well as inks and colorants used on those items. Preservation must occur while still allowing access to the collections.

This daguerreotype plate, created to mimic those made in the 19th century, can be studied under an electronic microscope to determine its properties. Photo by Abby Brack.

This daguerreotype plate, created to mimic
those made in the 19th century, can be studied under an electronic microscope to determine its properties. Photo by Abby Brack.

The Preservation Directorate manages several programs to ensure this long-term access. Specialists in the Preservation Reformatting Division prepare collections of brittle material to be reformatted into microfilm or digital files. Staff in the Preservation Directorate’s Conservation Division and Binding and Collections Care Division address how an item is stored: the temperature, humidity, and light conditions of its environment, its enclosures, and its handling, including care taken so labels or other utility marks don’t deteriorate the item.

In addition, staff in both divisions treat the Library’s collections to improve their physical condition. This includes the deacidification of books and paper-based manuscripts–the process of removing acid–which can add centuries to an item’s life.

A recent example of a conservation project was the treatment of an artwork by “outsider artist” Martín Ramírez. Titled “Madonna,” the work was created on pieced-together envelopes. It was discovered tucked into the Library’s papers of designers Charles and Ray Eames, tightly rolled and chewed by insects. With permission from the late Ramírez’s heirs in Mexico, the artwork was cleaned, its holes were expertly patched, and it was flattened and framed. It graced an exhibition at the Library celebrating Mexico in December 2013.

Conservator Heather Wanser treats a rare Korean map. Photo by Richard Herbert.

Conservator Heather Wanser treats a rare Korean map. Photo by Richard Herbert.

Out of a Crisis, New Expertise

Modern preservation science is often traced back to the triage methods devised by an ad-hoc team of experts who rushed to Italy from around the world in 1966, following the catastrophic flood of the River Arno in Florence. Ancient artworks, books, manuscripts and other world treasures, soaked in water and silt, required speedy intervention if they were to be saved.

One of the so-called “mud angels” later established the Library’s Conservation Division and the Library’s first preservation laboratory. Today, the Preservation Research and Testing Division (PRTD) in the Preservation Directorate includes a set of recently renovated laboratories in the Library’s Madison Building on Capitol Hill. One is the Optical Properties lab, where new methods of analyzing collection items take place including X-ray diffraction, Raman spectroscopy, scanning electron microscopy and use of hyperspectral imaging and X-ray fluorescence and the Physical and Chemical Testing Laboratory, where housing materials are tested to make sure they meet preservation standards. There, conditions of storage areas–sampling of the air for pollutants, for example–can be assessed.

PRTD finds non-invasive ways to assess and preserve collections; devises ways to slow or halt deteriorating factors–such as the “iron gall” ink used in historic manuscripts and the acidity of wood pulp-based papers, which, left untreated, will yellow and crumble.

Scientific Sleuthing

Equipment developed by PTLP is being used by the Library to deacidify books and manuscript pages. Photo by Amanda Reynolds.

Equipment developed by PTLP is being used by the Library to deacidify books and manuscript pages. Photo by Amanda Reynolds.

Advanced techniques, such as hyperspectral imaging, are making it possible to learn things about centuries-old documents that previously could not be known.

In 2010, PRTD Chief Fenella France–a world-renowned expert in conservation science–made an exciting discovery while using hyperspectral equipment to analyze one of the Library’s top treasures, a draft Declaration of Independence in Thomas Jefferson’s hand. Hyperspectral imaging has allowed the Library to see previously obscured details of the 1791 Pierre L’Enfant plan of Washington, D.C., and four fingerprints on the handwritten draft of the Gettysburg Address.

The Library has also used hyperspectral imaging to establish links between a rare copy of Ptolemy’s 1513 “Geographica,” an atlas with hand-colored maps, and the 1507 Waldseemüller World Map, the first known document to have the word “America” in it.

The Library is able to publicly display the Waldseemüller map and Abel Buell’s 1784 map of the newly independent United States due to hermetically sealed encasements that control humidity and minimize oxygen. The cases were designed and constructed in collaboration with the National Institute of Standards and Technology (NIST).

“The most challenging part of what we do is knowing that you may be working with the ‘only’ copy, so that’s why the focus is on new non-invasive technologies that can reveal hidden, exciting information about our amazing collections,” said France. “Using current techniques, while looking to new high-tech advances that we can adapt, means we know more about our rare collections than ever before, and without even touching them!”

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