Err. when exactly do you mean by “dark ages”?
There are scads of stone molds used for pewter and lead products
(which were in regular production up until about the 1750’s) which
were mass production pieces, at least as they saw them (in Europe)
at the time.
There are also a variety of stone and fragments of fired
clay/dung/straw moulds that were used for bronze and precious metal
’production’ casting from the late Roman period, straight through
until the present. The stone moulded waxes went out of fashion about
1200 or so, but the Vikings had a regular production line going for
those oval bodice brooches, and there are hundreds of surviving
plate brooches all through European museums from the middle of the
’dark ages’. Nevermind all the late Roman Crossbow brooches that
seem to turn up under every rock and shrub.
Take a look at the Helgo workshop excavations in Sweden. There’s
another workshop on one of the Scilly Isles, (of all strange places)
but I forget the name at the moment. There’s also the Mote of Mark
workshop remains from western Scotland, from the 6th-7th centuries,
from about the darkest moments of the ‘dark ages’. Again, it seems
to be largely remnants of production moulds.
The 'clay+straw+horse dung" moulding investment as described by
Theophilus (1125AD) may smell pretty bad when you first start to
fire it, but it works surprisingly well, given what it is. And it
will handle pretty much the same sorts of objects that modern
investment will, undercuts and all. It just smells bad. Really bad
when first firing.
If you really want to talk about production bronze casting, take a
look at what the Chinese were up to: interlocking ceramic mould
blocks that could be interchanged to vary the decoration on cast
If you’re defining ‘production’ as quality as good as what we get
from rubber moulds and investment, and quantities in the hundreds or
thousands the way we tend to run them, then no, no one ever,
anywhere, did ‘production’ casting before these two key technologies
were invented. On the other hand, if you’re defining ‘production’ as
’enough to make a living, all day long, every day’ then there was
production casting done in any period you care to name for the past
several thousand years. It just got easier as time went along and we
had better technology.