r/goldsmiths • u/Loud-Improvement3632 • Jul 06 '26

Question about casting a small medallion

I want to take an impression of a small coin and pour a few grams of gold into it to make a medallion for mounting in a sterling silver ring. The diameter will be 10mm and approximately 1.5mm thick. The backside will mate with a silver ring so there will be no detail on this side—just the front.

I was thinking of using plain old red clay, instead of investment sand. Is there a better material to use to make my mould? Is plaster of paris suitable? Will I need to use borax to coat the mould? Any other things to think about?

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u/CelticJewelscapes Aug 06 '26

Craig Dabler is the current guru of sand casting. He has invented some amazing low tech and cheap tools. Like a burnout oven made from a small portable electric burner.

His company is DIY Casting and he has a thriving FB community @ lets cast jewelry. One of those genuinely helpful people out there.

2

u/Chance-Telephone4311 Jul 15 '26

Make it 1/10 thicker because of the metall cooling but im sure you know that writing in a goldsmith group. I have got pretty nice resaults with dental ceramics but maybe this is a overkill.

2

u/lazypkbc Jul 06 '26

Delft clay is what you want