On September 7, 2013 'Cassette Store Day’ will be organised in Belgium and worldwide. This day is a tribute to the audio cassette which is celebrating its 50 years anniversary. Participating music stores will be selling special releases on tape, and there will be various events revolving around this medium. The audio cassette is ‘hot’ again: It appeals to our feelings of nostalgia, and the merchandising with images of audiocassettes we see today plays on those feelings. Plenty of reasons to pay some special attention to the history of the audio tape, its conservation problems, its importance for the audiovisual heritage and the plans that VIAA has for this carrier.
Invented in the lowlands
On August 30, 1963 at the Berlin radio show, Philips presented the 'Audio Compact Cassette' as a medium to record and play sound with specially developed equipment. In a sense it is even an invention of the lowlands, because it was the Dutch engineer Lou Ottens that developed the idea in the laboratory of the Philips factory in Hasselt.Although the audio cassette underwent many technical improvements, the basic principle always stayed the same: A double reel wrapped in a plastic shell, with a polyester tape drawn between them that can be wound back and forth. The sound is stored on it by magnetizing metal powder and fixating it to the polyester, through a connection layer of polyurethane. The main improvement that the audio cassette underwent, was the choice for more and better metal coatings: first iron dioxide and chromium dioxide, later magnetite and iron dioxide mixed with cobalt.
At first sight, the content on the audio tape with a shell seems better protected than its predecessor, the ordinary magnetic tape. But it turned out that this technical advancement doesn’t necessary guarantee better preservation of the sound. Compared with ordinary magnetic tape, the sound on an audio cassette is less sure of a long life. The same amount of information is stored on a smaller surface area and a thinner tape. Most conservation concerns of the audio cassette have to do with this fact.
A first conservation problem is tape rupture. The thinness of the polyester and the strain of the player can cause fractures, which can be repaired with special mounting tape. It’s usually fairly easy to repair.
Another annoying problem is the so-called sticky shed phenomenon, making the tape sticky and unplayable. The classic cases of 'tape spaghetti’ are often caused by sticky shed: When playing the residue of the metal coating is piling up on the heads very quickly, causing the tape to be lifted from it’s track and becoming entangled in the player. Sticky shed is caused by the polyurethane - which fixes the metal coating to the polyester - absorbing moisture from the environment, causing the tape to stick. Although this phenomenon can be seen in all types of magnetic tape, audio cassettes are particularly susceptible, especially when they have been stored for long periods of time in a humid environment. The best known solution to be able to play these tapes again, is to dehydrate them by heating them for several hours. This process is called ‘baking’ among audiovisual archivists. However, not every tape that refuses to play is therefore affected by sticky shed. A faulty drive or even worn-out pads can cause a blockage. In such cases it is usually sufficient to simply screw the shell apart and replace it.
All the damages mentioned above, are still repairable, but the so-called print through effect makes it virtually impossible. As with the sticky shed, audio cassettes are particularly susceptible. For audio cassettes with poor fixed magnetization the sound on one tape rotation gets imprinted to the next. When playing some kind of reverse echo is audible: a few seconds before a particular sound is played full volume, it's already audible before, in the worst cases three or four times in a row. This problem is also caused by poor recording equipment or a low quality of the metal layer. Winding the tape at least once a year is the only (preventive) remedy. Only highly sophisticated digital audio restoration programs can still improve after digitising the sound to some extent.
The digitisation of the audio cassette is a priority
Another unique part of the collection of the VRT is the ‘Eleven November Archive’: dozens of interviews with witnesses of the First World War in the Westhoek region. The interviews may not have been recorded in a way that we would call scientific today, but they are known to be the oldest oral history archive about the First World War in Flanders.
And let's also remember the home recordings on audio cassettes. Whilst the camcorder allowed ordinary people to make home movies, the cassette player played that role in the world of sound. A blank tape in our recorder, an index finger on the record button, carefully waiting to tape that one song or maybe even the whole hit chart… Anyone over thirty has memories of this. Thanks to home recordings, many programs that have never reached the broadcasting archives are probably, still preserved.
VIAA will digitalise audio tapes
The technology is aging and the carriers are certainly endangered, but the heritage value is indisputable. Therefore VIAA will also be digitising audio cassettes during its first digitisation wave. This spring, PACKED vzw during a survey for VIAA identified 7000 audio cassettes not digitised yet in the collections of official cultural heritage institutions. They will all be digitized in 2014. It is expected that this will take several months. It’s even likely that these files coming from the first audio cassettes, will be amongst the first to end up in the digital storage of VIAA.
(Author of this article: Brecht Declercq)