Soft Binder Syndrome (SBS) is a term suggested by Richard Hess to describe the type of media degradation that has previously been called Sticky Shed Syndrome (SSS) or Loss of Lubricant (LOL). The stick-slip action that causes squealing as the tape moves across the playback head, believed to be caused by a soft binder, is symptomatic of both SSS and LOL.1
Sticky Shed Syndrome
Open reel polyester tapes with back-coating manufactured since the 1970s commonly suffer from binder breakdown due to the absorption of moisture (hydrolysis).2 SSS can be tested for prior to playback by slowly unravelling the reel, and seeing whether the tape comes cleanly off the pack or if it sticks. If a tape suffering from SSS is played back, the heads and guides will quickly accumulate deposit, reducing high frequency response and often producing an audible squeal. Playback in this condition will damage the tape.
Squealing tapes that do not respond to baking
Loss of lubricant (LOL) may not be entirely accurate when describing non-SSS tapes that squeal, since lubricant is likely not the issue. In broad terms, LOL has been used for tapes that do not respond to incubation. This is confusing as tapes which squeal and do not respond to incubation have been shown to be carrying a normal lubricant load.3
Can these be fixed?
If the squeal makes its way into a digitized file, there is no solution at this time to correct the frequency modulated of the desired signal. There are methods, however, to prevent the squeal from occurring during playback.
Sticky Shed Syndrome
Removing moisture from the tape pack will get the tape to a playable state for digitization, which can be achieved by:
- Baking the tape in a scientific oven
- Baking the tape in a vacuum oven
- Dehydrating the tape in a food dehydrator
Cooking times and temperatures vary, and can depend on the severity of the hydrolysis. 55 degrees celsius (+/- a few degrees) with an incubation time of 8-10 hours is a good place to start.
Tape baking is a process first proposed by Ampex engineers upon learning of SSS. Ampex patented this process, but it has lapsed in the U.S.A. Ironically, the treatment violates the terms of warranty one enjoyed when first purchasing an Ampex tape. In the decades since proposing this remedy, other methods for fixing a tape have been employed, but baking/dehydrating remains the industry standard method.
Squealing tapes that do not respond to baking
Unfortunately there is no straightforward fix for a tape exhibiting loss of lubricant. The fix involves hardening the magnetic coating of the tape, and/or reducing friction between the tape and everything it touches during playback. Current options include, but are not limited to:
- Cold playback - lowering the ambient temperature to the tape’s glass transition temperature, i.e. playing the tape back in a fridge
- Holding a q-tip (cotton bud) continually moistened with D5 siloxane against the tape during playback
- Creating a steady isopropyl alcohol drip to cool and lubricate the tape during playback.4
These techniques employ slightly different mechanisms:
- Cold playback works by playing the coating at a temperature where it is harder.
- D5 decreases the friction between the tape and the head.
- Wet playback with isopropyl alcohol decreases friction and lowers the temperature, helping to harden the coating.
All tape suffers to some degree of stick-slip, but it is usually called “scrape flutter”. When the squealing becomes audible, the scrape flutter has massively increased, but it is the same mechanism.
Example(s)
Listen to a severe example of soft binder syndrome on SoundCloud
Listen to a comparison of a soft binder syndrome tape pre and post-baking on SoundCloud
Listen to a tape that does not respond to baking yet still squeals on SoundCloud
References
1. Richard Hess, “Tape degradation factors and challenges in prediction tape life,” ARSC Journal 39.2 (2008), 270-274. ↩
2. Kevin Bradley (ed), Guidelines on the production and preservation of digital audio objects, IASA TC-04 (2nd ed., 2009), 57-59, or here on the web edition of the TC-04. ↩
3. Richard Hess, “Tape degradation factors and challenges in prediction tape life”, 270-274. ↩
4. Marie O’Connell, Wet playing of reel tapes with Loss of Lubricant, RichardHess.com, 09 March 2006. ↩