We still use the Shield Pack sleeves for lacquer discs here at LC. I believe that the issue of inhibited air exchange arose from a very early practice of sealing the discs in the sleeves. Obviously that was a bad idea. Otherwise, we have not noted any problems with air exchange or accelerated degradation of lacquers. The only problem we have had with the sleeves - and this was with a later "batch" we had manufactured - was that the sleeves arrived badly warped. These we only use for rigid discs - glass or metal-based lacquers - and not for more pliable vinyl or even shellac.
Head, Recorded Sound Section
Library of Congress
>>> <[log in to unmask]> 02/14/07 9:44 AM >>>
>2. Is anyone familiar with foil-lined sleeves? I have not seen any
imprinting or other problems with the discs, but is there concern
of outgassing or any other problems?
These may be a type of sleeve known as the "shield pack". As far as I kno w
they have been discontinued not because the sleeves off-gassed but, because
they inhibited air exchange (i.e. created a micro-environment)and seemed to
in fact accelerate the degradation of lacquered discs, which of course do
I seem to recall that they were developed at least in part by the Library
of Congress and, if that's so, someone from LC could probably give you a
more complete history.
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