Study Reveals New Findings on Longevity of Legacy Magnetic Audio Tape

Findings suggest that polyester-based magnetic audio tapes that are playable today and kept at standard room conditions may remain usable for as long as 100 years


A new study published by the Council on Library and Information Resources (CLIR) suggests that a type of audio tape commonly used since the 1950s may have greater longevity than previously thought. Researchers from the Library of Congress’s Preservation Research and Testing Division and FUJIFILM Recording Media Products Division did a variety of tests on specific models of polyester tape produced 10 to 20 years ago. They concluded that the tapes in their research sample that are playable today and are kept at standard room conditions are likely to be playable for as long as 100 years into the future. The findings, presented in Accelerated Aging of Polyester-Based Legacy Audio Magnetic Tape Stock, could have significant implications for preservation planning of audiovisual collections.

Commercial polyester tapes were introduced in the 1950s and quickly gained widespread acceptance and use. While the polyester film itself is quite stable over time, the binders used in the magnetic layers of these tapes are susceptible to degradation. Some formulations are known to be widely problematic and have rendered tapes unplayable within decades. However, there remains uncertainty about the stability of currently playable historic magnetic tape recordings. The study addresses that question, which can be pressing for institutions that have large collections of seemingly good magnetic tapes. 

The study focused on two main areas. First, test tapes were subjected to a variety of accelerated temperature and relative humidity ranges, chosen to best predict and assess potential conditions for storage in institutions with and without controlled environmental options. Second, changes to the tapes’ physical, magnetic, and chemical properties were measured to assess their impact on the tapes’ usability. The key findings were as follows:


“Based on recommendations published 10 to 30 years prior to the time of this writing, the life expectancy for magnetic tapes was predicted to be 10 to 30 years if institutions adhered to published storage guidelines,” note the authors. “This study of legacy tapes at the upper end of this age range offers an opportunity to re-evaluate those blanket predictions.” The authors note that further research would confirm how broadly their findings apply to other models of tape.

Accelerated Aging of Polyester-Based Legacy Audio Magnetic Tape Stock is available electronically at

The Council on Library and Information Resources (CLIR) is an independent, nonprofit organization that forges strategies to enhance research, teaching, and learning environments in collaboration with libraries, cultural institutions, and communities of higher learning.

The Library of Congress’s Preservation Research and Testing Division undertakes scientific and technical research to advance and support preservation at the Library. The division works closely with the Conservation Division in establishing criteria and standards for supplies and techniques used in the Library’s conservation, housing, and storage activities in coordination with other offices, as appropriate.

FUJIFILM Recording Media Division delivers advanced data storage products based on a history of thin-film engineering and magnetic particle science such as Fujifilm’s NANOCUBIC and Barium Ferrite technology. Our mission is to enable organizations to effectively manage the world’s exponential data growth with innovative products and solutions, recognizing the social responsibility to protect the environment and preserve digital content for future generations.


Kathlin Smith

Senior Director of Communications

Council on Library and Information Resources

1800 Diagonal Road, Suite 600

Alexandria, VA 22314





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