Re: [AV Media Matters] Audio query

[rohre@ARLUT.UTEXAS.EDU]

The prevention of moisture absorption by the archived tapes is
paramount to their lasting 20 years, without the intensive labor of
re- recordings periodically.  The TV networks have a schedule that I
believe was 3 or 5 year intervals when back up copies are remade,
but I believe Masters are kept indefinitely.  But that is labor
intensive, and a drain on staff time.

There is no substitute for a neutral relative humidity, where no
moisture is taken up by the media, and thus you must lobby to have
adequate cool and dry storage.  I think Cuddihy of Jet Propulsion
Laboratories, CA.  (JPL) has extrapolated an indefinite tape
lifetime, if you keep it at 20 % RH and something like 40 degrees F.
My copy of his paper is not at hand, but there was a table of
lifetime vs. storage conditions.

There are reasonable off site environmentally controlled stores for
computer archives all over the country now, and facilities without
their own vaults might consider the specialist's services for
irreplaceable material.  Of course, you would still keep a Back UP
copy in your own facility, renewed as needed.  This might be the
best course for a museum in an older building without modern air
conditioning plant and complete humidity and close temperature
controls.

Stuart Rohre
ARL UTx Recording Lab