Stone Moulds for Pewter Casting

[Robert of Canterbury]

I just had a great day. I went up to the Herbert museum in Coventry and spent four hours with the curator in their archives looking at the 140 odd moulds and mould fragments they have.

Lots of eye openers, plenty of food for thought, a couple of answers to particular questions and a whole bunch of new lines of enquiry to pursue.

A few random observations,

the most common Mould thickness seems to be around 20mm. Some up to 28-30, one as thin as 12mm.

Keys/locking pins. most bored with a conical bit.

Male backplates. ony a couple, but they exist, and are quite complex.

air escape lines. Few & far between, far fewer than on most recreation moulds.

Stone. a few types represented, but no soapstone. Mostly some form of limestone/mudstone/ironstone. (one even had an ammonite in it )

some Photos to follow.

[Thomas Powers]

'some Photos to follow"

Oh *goody*!


Thomas

[Derian le Breton]

Not medieval, but you might be interested in these:

http://www.flickr.com/photos/derianlebreton/593703810/
http://www.flickr.com/photos/derianlebreton/698429779/

Also, there was a thread a while back where Mac posted a set of known stone types for medieval stone molds for pewter casting. IIRC there were about 100 items, and there was one soapstone mold. Roughly a third were "unknown".

-Derian.

[Tracy Justus]

Oooooh, photos! Please!

The moulds that Derian posted are interesting. You can see in the first one that the mouldmaker used all of his stone- there's what looks to be a couple of beads (with divots for the removable cores) as well as the fibulae pins and an arc of half rounds. I wonder if the mould had more than one other half- there looks like holes for two sets of alignment pins.

I've never seen a antique mould before where both sides were preserved. I'm going to guess that the mould was held together for casting by wooden pegs. My husband saw an 18th c stone mould for lead shot at the recent Baltimore Arms and Armor Fair which used wooden pegs. Presumably the stone would get hot enough that lead pins would melt.

Tracy

[Robert of Canterbury]

So, Photos.

All of these were taken with the Kind permission of the Herbert Museum and Art Gallery Coventry. Do Not copy these pictures without crediting the Herbert as the source of the Original object in the photo.

A broken piece of a mould for a lovely gothic beaker.



What looks like a Pawn or perhaps a finial. Slush cast perhaps?


The Base of a Candlestick mould perhaps?



a broken piece of a three part mould for two (or more) pin backed animal badges


Grommets?


A Male backplate. the channel revealed by the break is an air escape. You can see the two pinhole vents to the next vent on the surface of the raised lozenge. Too Cool for words. The fabulously cool thing is that i've already used a variant of this technique to get a mould to flow properly!



Another mindblowing piece, half of a backplate for a row of studs, with a male projection to make the final piece hollowed out.(Sadly not the best pic)



Crescents and a Wavy Star. Note the points left by the compass in marking out.



And Lastly, A whole bunch of backplate halves

[Derian le Breton]

Note the points left by the compass in marking out.

There's similar evidence for compass use in many ancient and medieval coins as well.

-Derian.

[Robert of Canterbury]

Derian,

Compass marks on coins - pimples in the centre of coins, indicating a mark left on the die by a compass foot? or something else?

[Derian le Breton]

Compass marks on coins - pimples in the centre of coins, indicating a mark left on the die by a compass foot? or something else?

Yes, when not covered by a design element anyway.

There is generally an engraved circular line underneath border beading; this seems to have been laid out with a compass. This helps when punching the beads, as you have a groove for the punch to "ride" in, resulting in uniform distance from the center of the coin.

Many reproduction coins do not use this technique, and have uneven border beading; this is a dead giveaway that the coin is a modern reproduction. Virtually no medieval coins have border beading that "wobbles". The same thing is true for the distance between beads; with medieval coins the beads are virtually always less than half a radius apart.

Many makers of modern reproductions do not pay sufficient attention to these details.

-Derian.