The 2,245th Meeting of the Society

November 21, 2008 at 8:00 PM

Powell Auditorium at the Cosmos Club

New Advances in Preservation Science at the Library of Congress

Eric F. Hansen

Preservation Research and Testing Division
Library of Congress

About the Lecture

The Library of Congress, the biggest library in the world, is both an international library and the de facto national library of the United States. In the Preservation Directorate, scientific research, technical and analytical studies, testing and quality control, predictive lifetime studies (“accelerated aging”) and treatment development have been formally conducted for over 40 years. Recently, the instrumental capabilities have been greatly expanded. Four projects involving the Preservation Research and Testing Division are presented: “Visual Storage” of the 1507 Waldseemuller World Map in the world’s largest anoxic encasement; hyper-spectral imaging and digital image analysis of documents; development of optical imaging instruments that use 2D and 3D non-contact scanning techniques to capture sound from grooved analog recordings for audio playback; and, possibilities for radiocarbon (14C) dating of parchment maps and photographs.

About the Speaker

ERIC F. HANSEN is Chief of the Preservation Research and Testing Division in the Preservation Directorate of the Library of Congress. He was previously a Scientist at the Getty Conservation Institute in Los Angeles for over 20 years. He is a fellow of both the American Institute for Conservation of Historic and Artistic Works (receiving the President’s Award from the AIC in 2006) and the International Institute for Conservation (IIC). He is the author of more than 40 publications and two monographs on the conservation of documents, objects, painted surfaces and architectural sculpture. He has studied the archaeology of the ancient Maya focusing on the sites of Nakbe and El Mirador in the Northern Petén, Guatemala. He received a master’s degree in Synthetic Organic Chemistry from the University of California, Irvine and his Ph. D. in Archaeology from the University of California, Los Angeles in 2000.


President Kenneth Haapala called the 2,245th meeting to order at 8:16 pm November 14, 2008 in the Powell Auditorium of the Cosmos Club. The minutes of the 2,244th meeting were read and approved.

Mr. Haapala introduced the speaker of the evening, Mr. Eric F. Hansen of the Library of Congress. Mr Hansen spoke on “New Advances in Preservation Science at the Library of Congress.”

Not an ordinary library, the Library of Congress is the de facto national library, Mr. Hansen said. It has 138 million items in its collection. It does 1,120,000 copyright acquisitions a year. It has 20.8 million catalogued books and 11.4 million books in large type. It has 105 million nonclassified items and 2.9 million studio materials, sound recordings of various types. The Library has 21 locks of hair. It is the largest library in the world.

The Jefferson Building, he said, has the most ornate interior of any building in the United States. He showed some beautiful pictures that amply illustrated his opinion.

It is a museum as well as a library and devotes considerable effort to conserving historical artifacts. Much of this work is done in the Preservation Research and Testing Division, where Mr. Hansen works. This work has five focuses: 1) technology, 2) environmental studies, 3) traditional materials, 4) analog audio-visual materials, and 5) digital materials. Digital materials include compact disks and even flash drives.

He illustrated some of this work using the Waldseemueller 1507 World Map, which Martin Waldseemuller called “Universalis Cosmographia. It shows the Americas, Africa, Europe, the Atlantic and the Pacific. It shows the Pacific separating North America from Asia. This was about five years before the Pacific was “discovered” by Balboa.

A casual look at the Map suggests the image has been mostly lost. Only tiny fragments of the original red grid lines can be seen.

The Library researchers scanned the map in various colors of light at different sampling rates, making many monochrome images, each reflecting narrow range of the spectrum. Light emitting diodes were used because they are very cool and allow highly selective use of the spectrum. Very cool means they produce little heat, not that they are the latest gee whiz fun thing. Reconstructing the map image using these finely tuned scans produced a surprisingly detailed picture that appears to look much more like the original. Notably, the red grid lines appear quite whole. This is done using false color, or invisible parts of the spectrum. Using this hyperspectral imaging, they can even produce images of the mapmaker’s woodblocks as well as the watermarks in the paper.

The map is now kept in a case milled from a solid block of aluminum, donated by Alcoa. The case weighs 2,200 pounds. The back was milled to 1/16 inch thickness so it would flex and changing atmospheric pressure will not break the glass. The case is filled with argon. Oxygen atoms are fewer than 1/100 million. The case is double sealed. The inner seal protects the map; the outer seal protects the inner seal in another layer of argon with the humidity idealized for the inner seal. The case was designed to be brought in horizontally to avoid cracking the mosaic tile floor, itself a valuable antique.

Library researchers are working with the Holocaust Museum on documents from concentration camps. Ink was difficult to obtain and inks of various compositions were use. The ink composition indicates something of conditions in the camps. Also, communications were censored. Using hyperspectral imaging, they can read through the censors’ black marks. He described the diary of one Otto Wolfe, who wrote of keeping track of time by counting the phases of the moon. He pondered the question: were the Holocaust victims trying to make ink look like ink or were they just trying to write?

Mr. Hansen described efforts to preserve sound recordings. Sound has been recorded in a variety of ways. They are developing methods of restoring the physical objects on which sounds were recorded as well as ways to preserve the sound records. Recordings of dead American languages exist on wax cylinders almost 100 years old. Funguses degrade the wax and they have developed ways to treat the funguses. They have developed a way to “read” the cylinder with a laser beam without touching the cylinder. They use software to smooth out the patterns of scratched records.

In another tour de force by Lawrence Berkeley, researchers recently coaxed sound from a sonogram made by Édouard Léon Scott de Martinville in 1860. Scott’s machine involved a diaphragm and a stylus scratching rag paper coated with lamp black. It made a visual representation of a person singing 11 notes of “Au Clair de la Lune.” The picture was recoded into a digital sound file, making this the oldest sound playback in history. The French Academy of Sciences has several of Scott’s recordings on rag paper. Here it is, the newest, oldest sound recording in history, unplayed for 148 years:

Mr. Hansen also discussed radiocarbon dating. Since 1940, the radioactivity in the environment has changed greatly, making dating easier in that period. It helps authenticate substances like food, wine and scotch whisky because the radioactivity is held by the gelatin.

He discussed the Vinland Map briefly. He recounted some of the arguments. Notably, the ink has not “wandered” as much as usually occurs on a map printed in 1410. He mentioned the Gospel of Judas, an account of conversations between Jesus of Nazareth and his friend, Judas Iscariot. This document was found in a cave in Egypt in the 1970's. He mentioned the Rossi Map, supposedly drawn by Marco Polo or based on Polo’s travels from the court of Kubilai Khan to the Alaska coast. The Map shows the Aleutian Islands.

Concluding, Mr. Hansen gave credit to his colleagues at the Library of Congress and at Lawrence Livermore. He invited questions.

One person asked if the Library would cooperate with the Folger Shakespeare Library. Mr. Hansen said they might; they have not been asked to.

How are the wavelengths chosen for the hyperspectral imaging? Mr. Hansen said he believed it is determined by the LEDs available and the need for separation between wavelengths.

Responding to a question about values of their work, he discussed deacidfying books. He mentioned the historical benefits of being able to do such things as recover the sounds of lost native American languages. He said that if one’s esthetic values are such that one prefers an old record with a scratchy sound, one might not see much use to some of their work.

He was asked about C14 dating. He said many things affect it. He showed a remarkably detailed line demonstrating the amount of C14 in the environment. The line does wobble a bit, so there are many points where it does not determine age within about 100 years or less, but over longer periods it is quite definite.

Someone asked about characterizing inks. There were many formulas for inks. The Library is working on a decision tree. The Chinese used inks with a lot of tannin in them, for example. He mentioned that the Library never authenticates anything; they only say it is consistent or inconsistent.

Mr. Haapala presented a plaque commemorating the occasion to the speaker. He announced the next meeting. He announced the upcoming election and invited nominations from the floor. There were none. He made a parking announcement. He discussed funding of the Society and encouraged contributions. He discussed the upcoming annual business meeting. By tradition, the Society has only one business meeting a year.

Finally, at 9:38 pm, he adjourned the 2,245th meeting to the social hour.

Attendance: 48
The weather: Brisk and breezy, mostly clear
The temperature: -2°C
Respectfully submitted,

Ronald O. Hietala,
Recording secretary