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Saturday, June 1 • 11:15am - 11:45am
(Research and Technical Studies) Rapid, Minimally Invasive, Identification of Degraded Audio and Video Magnetic Tapes

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The Library of Congress (LC) holds more than 500,000 magnetic tape objects, many of which are degrading rapidly. As at many cultural heritage institutions and archives, a rapid method to identify degraded tape is needed to facilitate treatment prioritization before copying and/or digitizing. Even in ideal storage conditions, tapes degrade. Tapes produced during the 1970-1990’s often contain polyester-urethane (PEU) binders that hold magnetic particles onto polyethylene terephthalate substrates. PEU binders are known to degrade via hydrolysis, which causes squealing and/or shedding of magnetic material onto playback device heads. This condition is referred to as ‘sticky shed syndrome’ (SS). There are no known non-destructive methods for rapidly identifying degraded magnetic tapes. Several brands and models of tape are known to contain PEU binders and are known to degrade, however tapes are rarely held in their original packaging or even kept on original hubs, making classification by visual inspection impossible. Playing a tape is the currently accepted method for classifying a tape as SS or non-SS. If the tape squeals, flakes, or gums playback equipment, it is classified as SS and removed from the digitization workflow for treatment. This process can not only render the playback device unusable, but it can permanently damage the tape and lead to loss of data.

Assessment of 100 LC ¼” audio collection tapes led to the development of a method for the rapid identification of degraded tapes prior to playback. Using Fourier transform infrared (FTIR) spectroscopy combined with multivariate statistics (MVS), the method’s rate of accurately assessing tape condition was better than 98%.

This talk will focus on the application of the classification model produced from LC collection-based ¼” audiotape FTIR data to other formats such as U-matic, VHS, and ½” video. The ¼” dataset classification model was also applied to data collected from ¼” audio reference tapes of known provenance spanning multiple manufacturers and models. Establishing the applicability of the classification model to a broad and known set of tapes was completed to predict the usefulness of the model for collections outside of the LC and may allow for the identification of specific makes and models within a particular collection. In addition, direct analysis in real time mass spectrometry (DART-MS) was conducted on a set of degraded and non-degraded ¼” audio and ½” video tapes to investigate their chemical differences.

FTIR combined with statistical analysis is envisioned as a tool for rapid, on-site analysis of collection materials. However, attenuated total reflectance (ATR)-FTIR directly contacts the tape, and its use may affect the surface and possibly the sound or image fidelity. Modern ¼” audio tape was pre-recorded with standard test tones, subjected to ATR-FTIR testing, and played through an analog to digital recorder. The post-ATR-FTIR signals were compared to the pre-recorded signals at the same locations. The results of this testing will also be discussed.


Peter Alyea

Sound Engineer, Library of Congress
Peter Alyea is a Sound Engineer in the Preservation Reformatting Division at the Library of Congress and has been the project lead at the Library on the IRENE project, in collaboration with Lawrence Berkeley Livermore Laboratories.

Eric Breitung

Scientist, Library of Congress
Eric Breitung is a physical organic chemist with ten years of industrial research experience in coatings and thin-films. He began working in the field of art conservation science in 2006 as an Andrew W. Mellon Fellow at the Metropolitan Museum of Art&#39&#59;s Department of Scientific Research, where he developed novel methods for treating and producing scratch resistant large-format face-mounted photographs. A side project... Read More →
avatar for Brianna M. Cassidy

Brianna M. Cassidy

Ph.D. Student, University of South Carolina

Samantha Skelton

Ph.D. Candidate, NACCA, University of Glasgow/TH Köln
Samantha is a Ph.D. Candidate in the Marie-Curie research and training network "New Approaches to the Conservation of Contemporary Art" (NACCA), coordinated by Maastricht University. She graduated in 2014 from the Winterthur/University of Delaware Program in Art Conservation, specializing in paintings conservation. She graduated summa cum laude from the University of South Carolina in 2011, with an Honors BA in Art History and minors in... Read More →

Saturday June 1, 2013 11:15am - 11:45am
JW Marriott White River Ballroom A-B 19 S West St Indianapolis, IN 46204

Attendees (18)