Actually this was very helpful. 400K disks is a sort of roundabout
figure. Thank you!

With respect to White Christmas, I don't know even know the origin of
the master. I know in 1943, when they recorded the Rodgers and Hart
revival of "A Connecticut Yankee" they actually used glass.

DrG

On 1/22/11 4:36 AM, Jolyon Hudson wrote:
> 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
>