Just had a wonderful dinner with great company and some discussions on Pewter casting were had with Tanw, so I need to get them down whilst I remember.
Tanw was suggesting that the issue with pouring a nice thin hollow cast might actually be that the alloy used in modern pewter isn’t anywhere near the same as what was used in period. Modern “Brittania” has absolutely no lead content, it’s usually a mix of tin (93%), copper (2%) and antimony (5%), whereas period Pewter varied greatly in it’s alloy make up, but was primarily tin and lead, as long as tin was more than 51%, it was classed as Pewter. He suggested that it might be worth experimenting with these more period pewters, as it might be easier to get a thin walled hollow casting. While I’m on the subject, my theory on the wall thickness of the period pieces is based on the fact that most photo’s I have found seem to make the hollow pieces look like ther are actually squashed flat to some degree. This would not be possibly without a large amount of pressure on the experimented pieces I have currently made.
Plumbers solder these days could therefore possibly be used as the basis for a more period form of pewter, as it is purchasable in 40T/60L 50T/50L or even 60T/40L mix, and only requires the addition of more tin to purify the pewter. Blackwood’s can supply solder sticks, as well as a pure stick of tin, which would make making a period Pewter mix easily, however I suspect that I’m going to have to purchase packs of 20 and 25 sticks… This is however now the plan, as providing a pure period example, complete with the correctly mixed alloy, would be something that I would find very cool to do. The multiple stick option gives me an easy way to experiment with mixes, though I’ll need a small melting pot that fits nicely on my burner to mix them in.
Tanw also suggested that it might be worth looking into the smelting process, and checking to see whether there are any other metals that are accidently left in the tin or lead after smelting due to the imperfections of the smelting process. This is something else I shall research, and hopefully the Brian Spencer book I am awaiting might shed some light on the metallurgical consistancy of the period examples.
Anyway.. Way past my bed time. Night all…
Wait for the book. It has the different alloys used according to the end product’s use and finish required. When melting your alloy, make sure you have a gaseous filter mask. Also, the reason most of the ampoules are squashed flat is that the contents had been used and the ampoule as hollowware was no longer required. Also, many came out of digs and had many layers of ‘other stuff’ on top. Modern pewter also sometimes contains bismuth.
Ahhh Hey Tyg! Thanks for that.
The Hollow-ware attempts I have tried wouldn’t squash flat, even if you stood on them… The wall thickness is only about 1.5mm, however the modern pewter alloy is slightly stronger/harder than say a 60t/40l solder. So my theory is that the wall thickness is a fair bit thinner as well as the alloy being slightly softer.
It’s also interesting to note that most Ampullae discovered have been crimped closed. The alloy would need to be fairly soft so crimp seal easily without the need for special tools. Considering that they are virtually tourist souvenirs, I find it hard to believe that they would make them hard to crimp.
Though I’m just theorising here, because it’s fun to theorise about it, and then get proof later.
1.5mm thick!!! Not surprised as that’s a reasonably standard ring thickness!! Hadn’t realised your castings were working out that thick to start with.
coupla secs later… they’re going to need to be shim thickness. You’re talking 0.5mm or less and yes, way more lead in the mix.
Yup, that’s why Tanw was suggesting looking into the alloy. Which also means that the finished product would be even more of a period recreation.
Looking forward to playing…