Chemistry for Audio Heritage Preservation: A Review of Analytical Techniques for Audio Magnetic Tapes

Abstract

Vast and important cultural resources are entrusted to magnetic tape around the world, but they are susceptible to degradation, which may lead to severe replay problems. Audio magnetic tapes are complex and multicomponent devices containing organic compounds and metal systems, which can be potential catalysts for many degradative reactions in the presence of water, light, or heating. The aim of this review is to collect the literature concerning the analytical determinations and instrumental approaches that can achieve the chemical identification of the components in the tape and the degradation state. Thus, a combination of destructive (such as acetone extraction) and non-destructive techniques (such as ATR FTIR spectroscopy) have been proposed, together with SEM, ESEM, XRD and TGA analyses to assess the chemical and physical characterization of the tape with the purpose to individualize restoration treatments and optimize conditions for preservation. The impact of the studies reviewed in this paper may go beyond audio, being potentially relevant to video, data, instrumentation, and logging tapes.

Comparative study of degradation between the carbon black back coat layer and magnetic layer in magnetic audio tapes using attenuated total reflectance Fourier transform infrared spectroscopy and machine learning techniques

“…Most magnetic audio tapes mainly consist of two layers, and the heart of the audio magnetic tape is the binder/magnetic layer. This layer consists of magnetic particles, such as chromium dioxide (CrO 2 ), gamma ferric oxide (γFe 2 O 3 ), and cobalt‐doped γFe 2 O 3 , embedded in polymeric binder, which holds the magnetic particles to the next layer, the base film 3,4 . The most common binder used in magnetic audio tapes is polyester polyurethane (PEU), and different PEU materials are used in the magnetic tape industry to improve physical, chemical, and mechanical properties of audio magnetic tapes 5,6 .…”

“…Apart from that, the binder contains liquid or solid lubricants to reduce the friction between the tape and the tape guides 6 . The next layer, the base film, is commonly made of polyethylene terephthalate (PET), and this layer provides the structural support to the entire tape 3,6 …”

“…The main reason for this is degradation taking place in the above‐mentioned tape layers. Degradation can occur in many ways, including temperature and humidity of the tape storage; chemical nature of the tape layers; exposure to liquids, dust, debris, or corrosive gases; exposure to a strong magnetic field; and mechanical stress employed on the magnetic layer during tape playback 3,5 . Because there are various methods in which degradation can take place, it is difficult to narrow down one method and study that for various tape chemistries.…”

Rapid Prediction of Polyester Magnetic Tape Playability Using Water Contact Angles

“…These problems can permanently ruin a tape and jeopardize its contents. A number of researchers have undertaken studies to understand the causes and characteristics of degraded polyester-based audio materials [4][5][6][7][8][9][10][11].…”

“…Options for addressing tape degradation become more scarce and valuable when restricted by increasingly-hard-to-find playback equipment (which necessitates protection from sticky tape shed), limited personnel and expertise, and remediation methods that can be both time-intensive and equipment-intensive. Researchers have identified potential methods for identifying degraded tapes, but these methods presume a significant degree of technical know-how and possession of expensive analytical tools [6], [9][10][11][12]. A cheap, rapid, and non-technical tool to evaluate the condition of a tape prior to playback might tremendously aid technicians in their daily workflow and aid in the preservation of magnetic media.…”