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Re: [AV Media Matters] Digitizing Audio and Video
John
By "cycling" I assume that you mean rewinding the tape every few years.
That originated in a 1958 report by GKI. It does not apply to
backcoated
tapes, which were introduced in the late 1960s.
In 1978-79, Ampex was contracted by the U.S. Air Force to update the GKI
report. In 1981, I was asked by SMPTE to summarize the data from the
U.S. Air
Force report. This resulted in the article that I wrote for the SMPTE
Journal.
It was in the June 1983 Journal and was titled "Long-Term Storage of
Videotape". That article catapulted me into the limelight of the world
moving image
archival community.
In the SMPTE article, I quoted the Ampex study that said that tapes
stored at
70 F should be rewound about every two years. At least this was better
than
the six month figure from the GKI report.
Since I wrote the SMPTE article, I have given a lot of thought to tape
rewind
intervals. The obvious question is "why rewind?" The reason is to
minimize
distortions in the tape pack. The next question is "Why do tape pack
distortions occur?" The answer is because of changes in pack
temperature during
storage and because of incorrect tape wind tensions just before storage.
If a tape is wound at 65-70 F, at the correct tension, and stored around
65
F, then tape pack distortion should not occur and rewinding is NOT
necessary.
Even if you do find a tape with pack distortion, the tape can be
returned to
normal by a couple of high-speed winds.
In summary, wind the tape before storage and store the tape at a
consistent
temperature.
Several of us on this Listserve agree that winding tapes every few years
is
more likely to damage the tapes. Let them set on the shelf and age
naturally--or is that organically?
BEST
Jim Wheeler
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