SubscribeFinally! it’ been a while since I posted a pewter project post, but I have now got a few projects on the go so there will be a number of them coming in the next month or two.
This weeks project has been a personal token for an SCA member to give to those they favour. It is a simple medallion with initials on one side, and a raised representation of a logo/device on the other side.
Usually my medallions are carved into one side of the mould for depth and then the other side is smoothed and has the detail carved into that. For this particular token I wanted to attempt a fully symmetrical moulding process by carving half the depth into each side of the mould. I did this for two reasons, firstly, the one sided method I used previously whilst it makes for a nicer edge, usually needs alot more work to clean up. Secondly it allowed me practice in aligning the two halves of the mould, whilst the old method allowed for misalignment, it meant that the main image was not centred on the finished token, and it would look kind of wrong.
After some experimentation in attempting to get a good quality pour each time (see last post), I managed to find the best combination of temperature and mould tapping that resulted in a great amount of detail showing. This further experimentation also made me realise the importance of the mould tapping and the continuation of it until the entire button* has solidified. It seems that during the freezing process pewter can sill move past other parts that have frozen solid. I suspect this would be similar to the crystals of ice that form in water, they allow water to pass around them, but still hold their shape.
Interestingly this also brings to my attention the creation of another type of artefact on an improperly cast item. This artefact is caused if the mould moves during this crystallising phase of the freeze, and creates a texture like the one in the picture to the left. It is rather a fine texture, however given the choice of all three of the artefacts described here and in the last post, I would rather this one, as the detail of the casting is almost perfect. To reduce or even eliminate this artefact I would suggest the use of either wiring the mould together tightly, or using mechanical clamps to stop the mould from moving during the tapping and pouring process. I may even attempt to make some sort of mechanical tapping/shaking jig so as to reduce stresses on the soapstone mould as well as the chances of the mould moving.
In a happy coincidence when I was checking the email to confirm that I had gotten the commission done as requested, I noticed that I was missing a vital part of the Dragons. So the above information about the tapping/shaking process was only discovered after the wings were added, and the entire batch recast. I’m sure my customer will be much happier with the better detailed casts than he might have been with the previous batch, specially as his Dragons are now actually dragons and not Lizards. ;)
