RE: [AV Media Matters] RE: Video storage

[Jim Wheeler <Jimwheeler@aol.com>]

George

The recommendation to rewind tapes came from a GKI report in 1959.  In 1979,
Ampex performed a tape study for the U.S. Air Force and one of the
conclusions was that GKI had made some wrong assumptions.  The Ampex report
recommended more studies were needed and that rewinding every 3.5 years
should be a good policy.

My conclusion (after talking with some of the people involved in the Ampex
study) was that they felt that some figure had to be given and 3.5 years was
reasonable.

There are many variables but the largest variables are layer-to-layer
friction, temperature variations and humidity variations.  If the
environmental variations are kept to a minimum and you use backcoated tape,
the pack stresses will not change much.

The SMPTE RP-103 committee ended up recommending rewinding every ten years.
No one on the SMPTE Committee had any data.

I'm not aware of any archive rewinding their tapes periodically and I have
not heard of any problems in data archives or video archives due to tape
pack
stresses.

Jim