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RE: [AV Media Matters] Recovery of AV media in flood disaster

Just a few comments on Stuart's advise.  We are a facility that specializes
in magnetic tape disaster recovery and have handled many thousands of tapes
effected by a wide variety of "flood" conditions.  From the description it
sounds as though Stuart was dealing with some of the older, more robust tape
formats.  There are a few extra precautions that should be taken with some
of the newer tape formulations and formats.

First, many of the new tape formulations use active metal particles.  This
includes most digital formats.  While iron oxide does not rust, the new MP
and ME recording pigments do.  The ceramic coating passivator seems to hold
up fairly well under normal situations but, submerge MP or ME tape for long
enough and, no matter how cold the water, the passivating coat will fail on
some of the pigments and the pigments will oxidize.  This will, not
infrequently, set up a cascade effect and eat right through a portion of the

Second, any impurities in the water that introduce metal ions into the
equation can catalyze hydrolytic decay where the tape touches the metal
posts that are used in the cassettes of some newer formats.  When this
happens, the backcoat is damaged and the tape adheres to the posts.

Third, most of the new formats are quite delicate.  Saturation decreases the
elastic properties of magnetic tape.  You must be much more careful with any
attempt to spool the newer, smaller tape formats when they are wet than was
necessary with the older, more robust tapes.  The tension created by the
weight of the plastic reel alone can be sufficient to deform 19mm, 1/2" or
8mm tapes beyond their ability to recover if the tape is spooled while wet.

One final bit of advise.  Most tap water, in this country at least, has a
fairly high chlorine content.  Chlorine eats tape and exposure to
chlorinated water is about the worst thing that can happen to magnetic tape
in a flood.  Never rinse contaminated tape in tap water that may be
chlorinated.  All water based rinsing should only be done with distilled

Peter Brothers
web-site: http://www.specsbros.com
SINCE 1983

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