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Preservation: The Sciences In Art And Art History

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  • Preservation: The Sciences In Art And Art History

    PRESERVATION: THE SCIENCES IN ART AND ART HISTORY
    by Steve Rees, News Editor

    The Point News
    http://thepointnews.com/2011/03/preservation-the-sciences-in-art-and-art-history
    March 1 2011

    On Feb. 23, United States Library of Congress preservation research
    scientist Lynn Brostoff presented her studies of ancient artifacts and
    works of art using scientific methods in her lecture "Using Science
    to Unlock the Secrets of Art and Historic Artifacts" as part of the
    Natural Science and Mathematics Colloquium series.

    Given in the Schaefer Hall lecture room, Brostoff's lecture focused
    on her role in the field of cultural heritage science, which includes
    elements of biology, chemistry, physics, forensics, and materials
    science (the analysis of how an object's properties are linked to
    its atomic and molecular structure).

    "We're doing a lot of material science," said Brostoff, "and what
    the materials present say about the condition of the object."

    Brostoff discussed how the analytical study of museum and library
    collections is based on technical studies, model studies of degradation
    mechanisms, and conservation methods development.

    Technical studies refers to the study of a material's identity,
    methods of manufacture, the history of the manufacturer, innovations
    of certain components of the object, and the context of the object
    in relation to its found location.

    "A lot of people develop analytical tools specifically for the
    applications we have," she said. "The first thing we want to do is
    look at things non-invasively."

    Electromagnetic (EM) radiation is the primary method that scientists
    like Brostoff use to analyze artifacts non-invasively.

    The EM waves are scattered, reflected, transmitted, and absorbed by
    different objects, the results of which are detected and analyzed to
    understand more about the artifacts in question.

    Microscopy, spectral imaging, and Raman spectroscopy are other methods
    of analyzing these materials.

    When more analytical techniques are needed, the next stage of object
    investigation is the use of minimally invasive techniques, which
    includes calorimetry and even fold endurance testing on micro-samples
    of the object.

    Brostoff discussed examples of several artifacts analyzed by the
    preservation staff of the Library of Congress, including a fifteenth
    century version of the Armenian Gospel from Verin Noravank Monastery
    in Siwnik (Syunik Province), Armenia.

    The book itself was acquired by the Library of Congress in 2008,
    and has since been under intensive technical study.

    The objective of working with the book is to preserve the colors and
    text of the Gospel of St. Mark, which is inside the book.

    Beginning with X-ray fluorescence, or the use of X-rays to excite
    electrons of atoms on the surface enough to cause a detectable energy
    release, Brostoff explained how the artifact was analyzed in terms
    of the colors used on one of the pages.

    The X-ray fluorescence, or XRF, detected tin oxide in the work, a rare
    white pigment that was used to make the white color used on the pages.

    XRF also detected smalt (a cobalt glass material from arsenic ore)
    used for the blue in the book's pages. This finding was especially
    surprising, as it was thought that smalt was not used until Venetian
    paintings over a century later.

    Further analysis of the blue pigments on the page with Fourier transfer
    infrared spectroscopy (FTIR) indicated the presence of ultramarine,
    a silicon oxide compound also known as lapis lazuli, found almost
    exclusively in what is now Afghanistan.

    Further cobalt traces indicating smalt presence were verified with
    elemental analysis. Doing all of these tests aided in accurate
    identification of the pigment compounds.

    "We could have missed the pigment elements by doing only one analytical
    technique," said Brostoff.

    The red pigment of the page was analyzed and found to contain mercury
    and lead, common sources of red in other works at the time.

    Further analysis with micro-XRD indicated lead tetroxide for the lead
    source, and mercury sulfide for the mercury source.

    The fact that all of these different compounds could be used for the
    painting makes more sense given the proximity of Syunik to the Silk
    Road, the main trade route of the time.

    The Persian influence can even be seen in the pages' artwork.

    "There is little known about Armenian painting," said Brostoff,
    "so this told us a lot."

    Another method of analysis used by the lab is laser ablation
    inductively-coupled mass spectrometry (LA-ICP-MS), which was used to
    analyze trace elements of Ancient Chinese gold.

    XRF was also used to analyze the moon dust left on the space suits
    of astronauts from the Apollo 17 mission.

    "You can never see with the naked eye where we've been," said
    Brostoff. "And digitizing does not replace study and analysis."

    "I thought the lecture was interesting," said Kevin Tennyson, a
    first-year Physics student who attended the talk.

    "I have an appreciation for the physics of it, and the materials
    science that I personally would not have thought of."




    From: A. Papazian
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