KBOO sent out open-reel tapes for digitization and received preservation master audio files back recently. Part of the archives & preservation being performed now is audio quality control on the items, and entering technical and descriptive information into the KBOO archival database.
Of the 109 items sent out, seventeen items were identified to have a condition called sticky shed syndrome. This is a hydrolysis process that causes breakdown of the tape's binder (see below). When a sticky shed tape is played back, there is risk of damaging the tape. When this severe condition risk was identified, our vendor baked the tapes. Baking tapes (introducing the tape to low, dry heat) is a specific, temporary repair process that is performed to counteract sticky shed on polyester-based open reel tapes.
However, tapes are at risk of deterioriating more quickly after a bake so unnecessary baking is wearing of the tape. To prevent sticky shed, archives need to keep open reels in controlled temperature and humidity levels.
Creating preservation wav files is important work for an audio archive. This means capturing the best representation of the original recording without editing--complete with background noise and all. The target quality is 96 kHz at 24 bits. If files need editing for clearer sound, or to trim beginning and end audio, a copy of the preservation wav file is made at a lower sample and bit rate--this derivative file can become the edit master, or might be called a mezzanine file. And then the low resolution listening copy is often a lossy mp3 file (a non-reversible removal of data to reduce the file size).
Want to get involved in the KBOO audio archive project? RSVP for the free community Edit-a-Thon event on Saturday, March 25, 2017. Learn more at kboo.fm/editparty2017 or email firstname.lastname@example.org.