A friend was interested in getting some made. I expect that bronze moulds came into use in the 14th or 15th century, as we have inventory evidence for them but this Shire book says the 13th, although I’d like to know his evidence:
What has occured to me is that the lack of stone moulds for casting pewter objects is partly due to the fact that metal moulds were used, and they would be recycled when they went out of fashion. Of course that still leaves plenty of small things to be cast using stone, and we know spoons were in the 15th century because of a mould fragment found in London.
Pictures of an 18th century spoon mould can be found here:
There is one small drawback to the bronze moulds though. According to the 1427 inventory of Thomas Filkes, a London pewterer, the moulds are:
A small charger mould of brass, weight 80lbs, value 26s 8d at 4d per lb.
A middle platter mould of brass, 54lbs, 18s.
And fourteen more in a list
The moulds weigh a surprising amount, with 80lbs being about 36kg of metal, all for a mould to make a charger, although I’m not sure what one is, embarassingly enough. The middle sized plate mould is smaller, at 24.4kg, but that is a lot of weight for what is used to cast a kilogram or two of metal.
Small saucer moulds weigh more like 16lbs, which is 7.2kg. So the moulds themselves would have been a few mm to, in places a cm or more thick, with a high heat capacity so you could cast into them repeatedly. The large mass is probably also to ensure that they don’t warp or change shape in any way during the casting. I suspect they would have greased the mould or dusted it with carbon black or sooted it with a candle, so that the pewter would release easily from it. Either way these moulds would have had a long life, and the total value of those in the workshop in 1427 was £16, which I think would be a couple of years wages at least!
Nowadays bronze isn’t quite so expensive, although the making of them would be, albeit maybe only a years wages (Average is about 26k now in the UK, the mode is, IIRC, more like 21k)
According to my source book (English Medieval Industries, edited by John Blair and Nigel Ramsay, published in 1991, 2001 paperback, absolutely essential for anyone interested in the medieval period and the industries that were big then), these would have been shared between two to six pewterers, which would at least help defray the cost of them. The pewter industry in London was huge, exporting large amounts to the continent in the 15th century, and there were pewterers in all the main regional towns, from Bury St Edmunds to BristolaSouthampton to York.
You can read some of the book here on google books, which is worthwhile since the book itself now sells for silly money second hand.
I sometimes think a new edition would be a good idea, but the basic framework will not have changed much, rather there would be more detail, e.g. on pewter and copper alloys more detail on the compositions and how they varied depending on the purpose.
Anyway, getting some proper bronze moulds is a worthy project, and hopefully it will work out okay.