For the last couple of days I have been threatening to show a niello cased
Cal. 57 pocket watch, which has been stripped of it's niello inlay - but each
time, got side-tracked by Tonny's post. Be it the actual watch he posted, or
the title of his post.
Today, I am just going to post this no frills, stripped niello Cal. 57 in all
it's glory.
Nothing to do with any riddle as to what movement it is - or even not a scarce
timepiece. The Cal. 57 whilst not as long lived as the C.52 movement, was
produced over many years.
The Watch

Is housed in a 0.900 German Silver case caring the Probus Scafusia logo -
however, in contrast to all other IWC (by standard) pocket watches, where the
watch (case) serial number is found on BOTH the outer and inner lids, the
outer case lid (seen here below ) whilst hallmarked and carrying the Probus
Scafusia logo, does not bear the watch serial number!

I was finally with help of a zoom lens able to capture and make out the three
small numbers stamped into the lip of the rear case back.
At first this puzzeled me. After all it was far to short a number to be a
watch serial number, as well as that entire lip is 1.55mm in width so why put
a 3 digit number there?

The numbers read: # 836 - and then I realised that as you can see here
below, these are the last 3 digits of the case/watch serial number!

When trying to understand why these numbers were stamped there, I consulted
with the craftsman who is my go to casemaker for repairs.
He explained, that in this case, the rear case lid (which is hinged - so when
made originally is a loose/seperate piece) was hand made to fit that
particular case number, 899836 and once it was finished/fitted properly, the
silversmith who completed the job, would stamp the last 3 digits of the
matching case for that rear lid on it. This, so that when the seperate
components came back from the external supplier who completed the niello work
/ inlay, they could assemble the matching case lid to the correct fitting case
without the need to have to find which case it belonged to by trial and error
fitting.
I guess, it was some sort of fall back / re-use situation, and if the rear lid
would buckle of resize during the niello process (which is as Adrian
previoulsy explained too) a heat based process, then it would be very easy to
remove those lightly stamped three letters, and hand rework the case back to
fit another case - whereas, if they stamped the entire serial number in the
lid, it would not be re-usable and they would have to smelt it down again.
What is intriguing to me is that whilst when looking at the detail of the case
work, one can clearly see that in some places (like just under the actual
crown on the crown neck) there is a clear and still intact niello inlay. See
the solid semi circular stipe of niello here below).

But, where there seems to be no niello inlay left on the engraved deeper
sections of the case - in an exact opposite manner than to traditional inlay,
there seems to be traces of niello onj the upper (higher) surfaces of the
case.
I have not seen this before. This phenomena (wow that's a big word for me! )
carries through to the case back....

where again, only the higher lying areas of the case seem to be "blackened".
The gold cartouche for engraving remains blank (albeit with scratches).
This is also the case for the very nice "penny edge" finishing on the side of
the case.Only blackend on the high points.

One can only wonder as to how this case looked like originally - in some form
of black on silver. Was it in fact originally niello or some other finish?
Possibly, a later attempt by someone to redo the case finish? I have no idea,
but all in all even in it's current condition with that case work as is, it is
a very nice pocket watch with a Cal. 57 movement.
Later once I was told about those three case number stamps, I looked again -
and indeed we find it as well, on the inside of the actual case too ; just to
the right of the hinge!

The Cal. 57 is in fair condition and as can be seen here below (serial number
removed to protect the innocent), is yet to be fully serviced and restored.
This lovely watch is patiently awaiting that day - which judging by the lack
of any service marks whatsoever on the watch, has probably been the case since
1929 when she left the manufatury in Schaffhausen,