From RON HIBBERD
Re ‘tape resurrection’ (Technology, 5 March and Letters, 26 March):
we have had the problem of magnetic tapes with the older polyurethane coating
degenerating to such a stickiness that they simply jam in the machines.
We have already tried James Watson’s method, using isopropanol, which only
worked for us on short runs of moderately degraded samples.
There is another method, though it is somewhat anti-social. We cooled
the heads with a liberal quantity of CFC and then sprayed the incoming tape
on the base side as the machine was run. This freezes the magnetic coating
to a solid that reproduces as normal, for a while anyway. Even in a room
with artificially reduced humidity this causes a build-up of ice around
the deck.
For long runs, we made a housing of foam polystyrene around the works
and fed it with dry nitrogen that had been chilled in a copper tube coiled
through a freezer. This works a treat. I guess any source of dry cold gas
would do quite as well – though I can’t recommend propane!
Ron Hibberd Leichhardt, NSW, Australia
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