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At 05:28 PM 6/27/2005 +0100, Prentice, Will wrote:
>We have two sets of "The Complete Caruso" (GD60495), a 12 CD boxset in
>the RCA Victor Gold Seal series, published in 1990 and manufactured by
>BMG Music, New York. One is suffering from a problem I haven't come
>across before.

>The 10/90 set have a curious crystalline frosted effect on the underside
>of the discs, rendering them unreadable. The interesting thing is that
>the frosting is on the outside of the polycarbonate, i.e. NOT in the
>metal reflective layer, where other problems such as bronzing manifest
>themselves. When gently rubbed with a lens cloth the frosting
>(crystals?) seem to come off, although I haven't attempted to clean an
>entire disc and play it, for fear of causing further damage. It appears
>to be a result of the exposure of the polycarbonate (or some element of
>it) to something atmospheric.

That set has an interesting history; I will summarize it for you from my
understanding but I have no references which will confirm the anecdotal data.

RCA sought and found an ink for the earlier set which matched the red of
the original red seal discs. The 1990 set was printed and sold with that
ink. Within a year or so, the discs were found to be failing; the ink was
quickly identified as the culprit. My inference had been that the ink
leached through the acrylic lacquer coating to corrode the metal; your
experience may be the form of failure since I have never encountered a disc
of that family.

At any rate, the set was reissued with different ink - presumably as you
describe from the 1993 set - and faulty copies were replaced.

You may find a chemical analysis of the crystalline material to be
interesting enough to be worth purusing. Outgassing of the ink alone may
explain the problem or it may be some interaction of gaseous products with
the polycarbonate. In any case, if the ink was the cause it is likely that
any cleanup will be temporary.

It is worth noting that the RCA set is the least highly valued of those
which are or have been available. The state of the art is considered to be
Ward Marston's recently completed collection for Naxos. His previous
transfer (I believe for Romophone, but it may have been for Pearl) is also
superior to the RCA, but he has found some of the earliest material in
better copy since then and has refined his processing somewhat.

Mike
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