OK, so after have many issues to solve with trying to quickly make the Double R’s for the Rowany chain’s, I thought I might share a few tips and hints to make difficult productions possibly a little easier.
Keeping your soapstone mould very hot helps to get the detail and also helps the pewter to flow into the extremities of the mould without too much trouble. Sometimes however, there are other issues involved in preventing a good pour.
When carving think of the flow of the molten metal as it passes through the cavity made by your desired mould. Frequently air pockets can cause issues making pour after pour fail to produce a worthwhile casting. Air pockets can be reduced by providing bleeder scratches which channel the air out of the soapstone but are too thin to allow pewter through before it sets. Sometimes however, it is not exactly possible to provide these bleeder scratches, as there is nowhere to take them that allows air to escape. This was indeed the case in the double Rs for the rowany chains. There was a loop at the end of the trailing leg of the R which build up enough pressure to hold back the molten pewter, not allowing it to complete the loop. various attempts at bleeder scratches taking the air out couldn’t get to the heart of the issue. In the end, the easiest meathod was to drill a 1mm hole through the soapstone at the centre of the loop, and provide bleed scratches into that. The down side is that if you drill directly through, you end up ruining the back side of the soapstone so that you cannot utilise that for making more moulds. To fix this, you could attempt to drill partially through from the mould face, and then in from the edge of the mould. This option provides an air passage, however preserves the rear face for more moulds. There is however another downside, should pewter get into the air hold, it will likely block it, and be a real pain to remove.
I’ve also had to drill an escape hole for the air when there is a loop. Be gentle when drilling, because it can crack the soapstone.
Where you’re only missing a tiny part of the cast, you could try making a small pit using your knife point, rather than drilling. It has worked for me. The air can’t escape as such, but it can compress.
- Crispin Sexi
Nice work on the chain.
I was a little puzzled about the level of finish. Were you casting in cuttle bone, I would have thought soap stone or plaster would have been better for mass production. It was a bit a shame as it detracted from the overall effect.
But I suppose there will be a clean up phase.
In period for that era it could have been stamped out hollow ware as well, so the option are all there. Makes for a lighter peice of regalia.
Any questions drop me a line.
Yes, I have tried that also.
In fact the double R moulds required both techniques . Thanks heaps for your input. 
If you ever have anything to add feel free. 
The level of finish was due to the level of commitment to those particular chains. The intent was to provide a sample of what they were to look like, as those particular chains are only temporary, and were only intended to last the evening. if they were to be the REAL chains, I would have either spent many hours getting the mould just right, or many many hours finishing up the castings so that they were neat and finished nicely. As it was, I had from Wednesday evening, until Saturday at the tourney to finish what was there from start to finish.
Carving, casting, cleaning and linking… and admittedly I left most of it for Friday. The linking was actually what took the longest as I had to draw out one of the links on each piece… Stupid mistake which could have been fixed by recasting them all with a longer tag/link.
It was a fun little high stress project, which will be repeated with the real chains in Silver as soon as the design is finalised. But for now, we have a Prop with the real Shields that Tyg has done a fantastic job on.