Cassette tapes were first produced at a mass scale in the early 1960s and became popular in the 1980s. Long before DVDs and cloud storage became popular, audio tapes and reels were used to record information. Magnetic tapes have a lifespan between 10 – 30 years and has been used to record and store sound, numeric and textual information, motion, and still images. While magnetic media adds on to the kind of artifacts, we can use to capture and store, their transience and degradability have been a concern for archivists and librarians.
To understand the reason for the degradation of audio tapes/reels, we need to delve into the components that form these tapes. Tapes have three parts – a magnetic layer, binder, and backing – all of which are potential sources of failure.
- The magnetic layer has a magnetic pigment suspended within a polymer binder.
- The binder holds the magnetic particles together and helps in recording and storing the magnetic signals written to it.
- The backing film supports the magnetic recording layer, which is very thin and cannot be a stand-alone layer.
All these components are susceptible to damage in the following ways:
Instabilities in the magnetic particle (top layer): If there is any change in the magnetic properties of the pigment that stores the recorded information, the recorded signals are irretrievable. The magnetic particle can become unstable due to demagnetization by an external factor like a hand-held metal detector, or suffer normal wear and tear.
Loss of lubricant in the binder: Lubricants reduce the friction of the magnetic top coat of the tape, reducing tape wear. With time, the level of lubricant decreases due to normal wear and tear, frequent consumption, degradation, and evaporation.
Substrate deformation (backing film): Polyester that is used as a substrate backing is chemically stable. However, excessive tape pack stresses, aging, and poor wind quality can cause deformation of the polyester in the substrate, thereby distorting the tapes.
Various factors result in the damage of audio tapes and reels. We have listed five of them below:
- Temperature and humidity: High temperatures and humidity can decrease magnetic capability, deteriorate the binder or backing of the magnetic tape, resulting in loss of readable data. Ideally, tapes should be stored at a temperature between 0° C – 23° C and in places with less than 70% humidity to prevent fungal growth and degradation.
- Frequent access: Frequent access reduce the life expectancy of tapes due to wear and tear. The more tape is handled, the more it is contaminated with fingerprints and debris, which reduces its life considerably.
- Exposure to the strong magnetic field: Strong magnetic fields like luggage screeners in airports, X-ray scanners, and metal detectors – both hand-held and walk-through – can erase information from audio tapes and reels, which uses magnetic particle to store data.
- Dust and debris: Dust, tape debris, and smoke particles can affect the tape when it is being played, resulting in loss of signal, and subsequently damaging the tape.
- Corrosive gases: Magnetic tapes are susceptible to airborne sulfides, ozone, and nitrous oxides. Bare metal particle (MP) and metal evaporated (ME) tapes, which are contained in cassettes, are affected by corrosive gases.
While storage options are aplenty now, audio tapes and reels are still of sentimental and historical value to librarians, archivists, and old people. While audio reels will degrade with time, some ways in which the decay can be contained are:
- Using and storing magnetic tape reels and cassettes in a clean environment.
- Avoiding contamination of the tapes by dirt, dust, fingerprints, food, cigarette smoke and ash, and airborne pollutants.
- Keeping the tapes away from strong sunlight and water.
- Not storing tapes near electronic or magnetic fields.
- Ensuring the reels are not laid flat for long periods while storing.
Having said all of that, it is best to create a back-up and copy of the information in modern formats to ensure there is no information lost.