Tape baking

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Audio cassette with magnetic tape.

Tape baking is a process that is used to restore magnetic tapes: audio cassettes and video tapes. It cannot be used with acetate tapes.^[1]

1 How baking works
2 When to bake tape
3 Methods of baking tape
4 External links
5 References

[edit] How baking works

Tapes deteriorate because of a breakdown in the binder that holds the oxide atoms on the tape. The binder contains polyurethane, which soaks up water and causes the urethane to rise to the tape's surface. This problem is known as the 'sticky shed syndrome'. Short strands of urethane were most commonly used in tapes (until it was discovered that middle-sized strands are better) and were good at absorbing moisture.^[2] Baking the tape temporarily restores the tape so that it can be safely copied to another tape or a different format. After baking, the tape usually remains in good condition for approximately a month. If the tape re-deteriorates, it may be possible to bake the tape again.

[edit] When to bake tape

There are some important signs that show when a tape needs baking. The typical symptom is squealing when the tape passes the playback head or other fixed parts of a tape player. The squealing is audible directly from the tape and also transmitted electronically through the output of the tape recorder. Another symptom is the tape sounding dull and distorted. Continuous use of a squealing tape risks permanently damaging the tape, as oxide is sometimes torn off the tape. There is also a risk of damage to the player.

Deterioration can happen to any tape, but the problem is more common with audio recording tape manufactured in the USA since the mid 1970s.

[edit] Methods of baking tape

There is no clear method or procedure for tape baking. Baking between 50 and 60 degrees C (120 and 140 degrees F) for approximately eight hours is one method. Normal domestic ovens are not used, as it is not possible to set and maintain the precise temperatures needed; particularly at the very low temperatures required for tape baking. Instead, convection ovens or food dehydrators are used.