Increasing ring size?

[Sim]

Hi all,

Just made a ring from PMC silver and it's shrunk a whopping 5 sizes. I need to get it up another three - how do I do this on a mandrel? I know I'll need to anneal the silver, but does that mean I hammer it hot, or after quenching? And do I just hammer up?

Thanks!

[Kwant]

Not sure you will be able to size it up by 3 without it cracking, but if you are going to attempt it, you anneal and quench before hammering on the mandrel. Being that PMC is fine silver, it is softer than sterling so you may be able to do it if you take it slowly and anneal frequently, remembering to slip the ring off the mandrel and turn it over repeatedly to prevent conical distortion.

[Sim]

Thank you! We'll see how it goes. I need to get it to size L, so it went titchy :/ I'll do as you said and hope for the best. Is it normally a maximum of two sizes you can increase? The middle could do with another round of polishing so I might get a bit of there too. Eventually

[Dennis]

If you once cut it you can achieve the correct size by pushing it up a ring stick manually. Then fill the gap with a custom made piece, soldered in.
I don't do clay, but also wonder whether you can fire some into the gap. Dennis.

[Kwant]

You could well be right there Dennis as there is a method of joining unfired to fired clay using oil paste and refiring, I have never tried this so not sure how effective it is, but a custom made piece soldered in is an intelligent solution :0)

[Sim]

Thanks all! I wanted to avoid cutting/adding if possible, as I'm not totally sure how the metal will behave. But I will use it as a last resort. Thanks!

[medusa]

wouldn't PMC be too brittle to size up on a mandrel? Not something I'd do myself, knowing how brittle the fingerprint rolls I make are. I think Dennis' idea is better or better still start again.

[Sim]

Yup, it cracked! I didn't even get to move up a size. Ah well, fingers crossed for next time

[medusa]

meh, if I'd have seen sooner, you might still have it. On the plus side you have some pure silver to boost the assay quality of your scrap pot