How do these numbers differ for vinyl records?

Roger




--- On Sat, 1/22/11, Jolyon Hudson <[log in to unmask]> wrote:

From: Jolyon Hudson <[log in to unmask]>
Subject: Re: [ARSCLIST] How many 78s to the Matrix
To: [log in to unmask]
Date: Saturday, January 22, 2011, 5:36 AM

The problem is really to do with how many stamper can be pulled from the
metal master and mother. In theory, and with care, this could be almost
limitless but in practice something often got damaged. It was feasible to
pull second metal master form the wax or acetate master but by the 1940s,
with improved processes for making duplicate stampers, the original wax was
unlikely to be kept.

With each cleaning of the mother and the subsequent plating process to
produce a stamper some wear would eventually occur so duplicate mothers were
often made for popular records so that you could continue the production of
pressings. Even then the mother would only last this wear and tear so long
and a new mother would have to be taken from the metal master.

So for a normal production of a record the stages would be:-

wax master > metal master > mother > stamper > pressing

The number of records a stamper could supply was somewhere in the region of
500-1500, stampers could wear out or something that got into the pressing
material would damaged a particular stamper. The abrasiveness and makeup of
the shellac would eventually cause the the metal in the stamper that equated
to the trough of the groove to flatten out and the different thermal
expansion and contraction rates of the metal and shellac from each pressing
would also contribute to further erosion of the stamper. Some groove
distortion would occur and the pressing material could very well adhere to
the stamper and ruin it.

So for a hypothetical production run of a million records a 1,000 stampers
could be required, clearly one mother could not supply this many stampers
and several mothers would have to be drawn from the metal master. Each stage
of this process had it's risks and even if no accidental damage was caused
to the original metal master it would still start to degrade from washing,
polishing and plating.

So if 20 mothers each produced 20 stampers which in turn each managed 1,000
pressings then that would equal 400,000 discs.

When I was looking at the microfilm of UK Columbia production cards of the
1920s at the British Library with Nick Morgan last year I was struck by the
failure rate of producing a stamper adequate enough to make pressings,
sometimes it took 10 attempts to get a satisfactory result - I wonder
sometimes how any records ever got to be manufactured.

There are so many variables to the manufacturing process  there is no exact
way to calculate what any stamper produced. Doesn’t really answer your
question! I would asume that something happened to the metal master and such
that no more mothers could be made