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Image showing four pictures of cabinets, with books, parchment, paper and CDs
Examples (Clockwise) of the Barrow, Parchment, Paper and Modern Media Audio/Visual Collections.

What a CHARMing Collection!

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The following is a post by Amanda Satorius, a preservation specialist in the Preservation Research and Testing Division. Her work includes completing historical pigment and paper production research, as well as expanding and preserving the Cultural Heritage Analytical Reference Material (CHARM) collection. She is also part of PRTD’s “Go Team” of scientists that use non-invasive portable techniques to improve understanding of collection materials.

One of the Library of Congress’s most CHARMing collections isn’t composed of collection items; the Cultural Heritage Analytical Reference Material (CHARM, formerly CLASS) is a collection of materials that preservation scientists have collected and created in order to expand upon the “discovery” aspect of Discovery and Preservation Services without risking Library collection items.

Three pictures showing storage cabinets with barcoded doors and item barcodes
CHARM storage cabinets (top) with examples of 3-level barcoding for each item, cabinet barcode (bottom left), shelf barcode, and item barcode (bottom right).

The Preservation Research and Testing Division (PRTD) analyzes the material composition of Library collection items to further scholarly research, conservation treatment, and the preservation of the collections. Without CHARM this can prove challenging due to the variety of collections housed within the Library, as well as the necessity of adhering to the minimally invasive/non-contact ethical approach to working with collection items during analysis. Many questions center on identifying unknown material components and understanding how an object’s current condition compares to its original condition, but there are also questions about production and provenance. While many analytical techniques can characterize the chemical composition and condition of a range of materials, including paints, inks, and pigments, coatings, and substrates such as paper, parchment, and papyrus, historically, this often required destructive sampling and invasive testing at the cost of damaging the item that preservation staff is attempting to conserve for future generations. Luckily, with the expansion of non-invasive, non-contact, micro spot size and portable instrumentation, the capacity for minimally to non-invasive analyses of collection materials has greatly expanded – allowing for deeper understanding of the Library’s collections.

Four images showing scientific instruments (clockwise) including X-ray fluoresence (XRF), fiber optic reflectance spectrometer (FORS), Fourier-Transform infrared spectrometer (FTIR), and a handheld portable microscope.
Portable instruments (clockwise) including X-ray fluorescence (XRF), fiber optic reflectance spectrometer (FORS), Fourier-Transform infrared spectrometer (FTIR), and a handheld portable UV-dual IR microscope.

In order to get more extensive information from non-invasive techniques, it is necessary to use known materials of specific compositions, degradation states and provenances. These known materials undergo both destructive and non-destructive analyses allowing scientist to decipher and identify the level of information able to be gathered from the less invasive techniques. These reference samples have become integral in the research PRTD, as well as preservation scientists as a community. CHARM evolved from the acquisition of the William Barrow Collection, comprised of approximately 1000 books (c 1507-1899) used by William James Barrow (1904-1967) in a series of scientific studies on the degradation of paper. CHARM has continued to grow and has become a pre-eminent collection of scientific reference materials.

In 2008-09 the Library established a specific location to strengthen consistency and tracking of storage conditions for these samples, and Preservation Directorate scientists began to create analytical profiles for them, documenting the specific instrument parameters and conditions used for testing. All materials in CHARM create a one-of-a kind analytical data set and reference sample collection that allows us increase our understanding of Library collection items, and also to begin to answer difficult natural and artificial aging questions about historical and modern materials. One example of the research and discovery opportunities found in CHARM is, the 100-year Paper Aging Study. CHARM now resides within PRTD, is environmentally monitored, organized for easy tracking of items, and also has a digital framework for searching item locations and storing their scientific information.

A pyramid of pigment jars stacked on a bench (left picture) and a box of small sample jars full of pigment samples (right picture)
Examples of our reference pigment collection.

The end goal for this framework is to create an integrated Web-accessible digital data library and an efficient process for requesting reference samples for use by staff and researchers to increase the reliability of preservation research data around the world. Stay tuned for future blogs on this CHARMing collection!

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  1. Thank you very much for the opportunity to enquirer

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