At 09:40 AM 6/16/2004 -0400, phirsch wrote:
please respond to the
>originator of the query below and not me

Responding to the list and the originator

>We have a collection of approximately 10,000 LPs. Roughly 15-20% of these
>records are discs which are covered within plastic wrapping (as opposed to
>paper or some other material). Years ago, I was advised that if plastic
>were left on the outside of the jacket, the jacket (and eventually, the LP)
>might warp over time. Can the same be said for the LP if the plastic is
>left covering the LP? In other words, would we be better off placing the
>discs in paper (or some other material) envelopes rather than leaving them
>in plastic? Many thanks.
>Scott D. Atwell, Ph.D.

>Big Rapids, MI 49307-2279 Email: [log in to unmask]

I believe I understand the query; if so, you are writing of two different
sorts of 'plastic' and two different issues.

Commercial LPs were often sold in a tight, transparent wrapper; it was
intended primarily to inhibit shoplifting (e.g., by making visible
inserting a second disc into the cardboard) and secondarily to prevent
damage to the cover. That cellophane-like material wraps so tightly that it
could over time and with normal heat/humidity cycles warp the disc. I have
known it to happen to discs laid flat for some months with no weight on
top, but have had many unsealed LPs stored for years in a normal, vertical
row and seen no effect.

I  believe you are writing about soft, flexible plastic sleeves which
loosely fit the disc itself; those are often used to separate the disc from
the cardboard sleeve and to reduce dust on the LP. Such a sleeve exerts no
pressure on the disc and cannot be responsible for warping. As far as I
have heard, the only associated risk is with an inferior plasticizer which
can coat the groove over time. I experienced that only with a few EMI LP
sets of the 1950s. It is recognizable as a graying of the surface - by
which time the disc is useless.

Please note; I am not a professional in this field and I hope that those
who are will be inspired to correct any errors above.

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