Would Argentium be better than sterling for casting stamping blank medallions?

[seb]

Hello,

I've had some 925 silver blank medallions cast, and I notice on some of them a cloud-like stain (doesn't look like fire scale or stain from what I've read...) than cannot be removed by polishing.
The caster can't explain why this happens, he says it just does on some series (which is why he casts small series at a time) and that it's the downside of casting vs die cutting.
I'm wondering if a more experienced silver caster can help me here.
1. Has anyone experienced this when casting 925 silver, and knows why this is happening?
2. If I use Argentium, could it effectively reduce problems?
3. Do you cast Argentium the same way as you do Sterling?
4. Is doing a Rhodium plating on Argentium really unnecessary?

Thank you in advance for your advice
Seb

[medusa]

Hi Seb,

I don't know about argentium, but I do know that sometimes I've had a bad batch of castings. Usually it only shows up when it's enamelled. the heat does something to it. If it can't be removed by polishing, and maybe depletion gilding, then I'd ask for a new lot.