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Magnetic recording
tape was never designed as a long-term storage medium. Tape is
primarily designed to be easy to use and easy to copy. Luckily,
magnetic tape is quite durable and can stand up to amazing abuse for
extended periods of time. If properly cared for, tape can actually
last far longer than the machinery on which it is played. Still, we
constantly see tapes pulled from storage in a state of advanced
decay, rendering the materials unusable.
The badly
deteriorating condition of many of the recordings in America and
around the world is due to one very simple reason: most tapes have
not been stored or handled properly. Tape is not physically
impressive. When it is not being used, tape makes no sound, provides
no picture, and to the casual observer appears unchanged over time.
But, just like any other material, magnetic tape decays when exposed
to harmful environments.
For years tapes have
been piled in odd corners, stuffed in attics and dumped in wet
basements to get them out of the way. Unintentionally, tapes have
been exposed to the most destructive conditions possible. There are
three primary environmental factors that cause tape to decay:
Moisture can be
absorbed directly from the air. This causes a chemical reaction
called binder hydrolysis. Molecules in the recording and backing
layers react with the moisture and break down, leaving a sticky
residue. Eventually the tape becomes too sticky to use. Binder
hydrolysis is the factor most experts use in predicting the life
expectancy of magnetic tape.
Heat aggravates binder
hydrolysis. It also causes tape to expand and contract producing
creases, stretching and structural damage.
Dirt and debris
contaminate the surface of the tape and block playback machinery from
reading the signal. A single speck of dust is 10 times larger than is
necessary to block the signal on a 1" tape! Dirt also gets
inside tape wraps, causing deformation and abrasion of the tape surface.
Storage environments
must be cool, dry, clean and relatively stable to maintain tape in
good condition. Proper storage can extend tape life by years or even
decades. If you are having problems playing back some of your tapes,
you should consider taking action now before additional tapes deteriorate.
Here are a few simple
tests to perform that can help warn of danger:
-
Walk around the area
where your tapes are stored. If normal activity causes you to sweat,
cough or sneeze, the environment is damaging your tapes.
-
Open the container in
which a tape is stored and sniff the tape. If you detect a smell that
can be characterized as "waxy," "dirty socks,"
"astringent/pungent" or "vinegar" your tape is
beginning to chemically decay.
-
Check the interior of
the container and any visible tape. Everything should look clean and
uniform. If something catches your eye, it probably shouldn’t be there.
Over the last few
years a lot has happened to bring the problems of preserving magnetic
tape to the public eye:
-
Major television
networks launched extensive preservation projects involving hundreds
of thousands of tapes.
-
Standards setting
bodies such as SMPTE and ANSI are creating, reviewing and publishing
guidelines on tape storage and handling.
-
The Library of
Congress held public hearings on "The State of American
Television and Video Preservation."
WRS can evaluate your
collection, assess environmental effects and determine the condition
of your materials. We offer testing, consulting and a variety of
restoration services proven to return "unusable" tapes to
playable condition. |
