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Written by the Digitisation and Digital Preservation team

Did you know the State Library has a special ‘oven’ that is critical to preserving our magnetic tape collections? 

Our AV (Audio-Visual) Preservation team is digitising to international standards all different types of recorded media that are in our AV collection. 

While working under the Deadline 2025 initiative to digitise magnetic media one of the conditions assessed and treated before digitising is a phenomenon known as Sticky Shed Syndrome (SSS). 

Magnetic tape types in the State Library's collection.
Various magnetic tapes that are often baked to help with the digitising process, 2025. Photo courtesy of Andrea Hensing-Matto. 

Magnetic tape is made up of layers - a base layer, a binder or adhesive, and the magnetic material which holds the recorded content. Over time the binders can absorb moisture so that the bind between the layers is not as strong.  Where the binder has deteriorated it can form a sticky residue that can damage the tape itself, and the playback equipment – also under threat of obsolescence.  

Some tape stock is more prone to this type of degradation than others and SSS is sometimes not apparent until you try to play the recordings. 

So how do we get around this to protect our valuable analogue recordings and playback equipment?  The answer is baking. 

The AV Preservation team places the tapes in a scientific oven, the Thermoline Scientific, set at a very low temperature for 24 hours.

Thermoline Scientific oven that helps preserve magnetic tapes in the State Library's collection.
Thermoline Scientific oven that helps preserve magnetic tapes in the State Library's collection. Photo courtesy of Laura Wolfe.

This process of heating basically dehydrates the binder layer of the tape, so that the layers are more strongly bound together again. This enables a smooth playback and digitisation of the tape -protecting both the tape and the playback equipment.  The AV Preservation team aims to digitise these baked tapes within the first few days after baking to achieve the best possible outcome. 

So far, we've had success in being able to digitise baked magnetic tape formats such as standard audio cassette tapes, reel-to-reel audio tapes, U-matic videotapes, VHS videotapes and 1-inch open reel videotape, among others. 

The digitised assets are ingested into our Digital Preservation System, Preservica - for preserving access to these collections into the future. 

So, what’s in the oven? 

The AV Preservation team are currently baking the Adelaide Grand Prix collection tapes!  

Adelaide Grand Prix cars in action on the track, circa 1990-2000. Courtesy of Messenger Press. SLSA: B 71771/24
Adelaide Grand Prix cars in action on the track, circa 1990-2000. Courtesy of Messenger Press. SLSA: B 71771/24 

For more information on Deadline 2025, see this article Deadline 2025 and this from the National Film and Sound Archive.