Casting Argentium using Delft clay?

Hi all,

I’ve been lurking on the list for a while. I’m interested in copying
antique French horn mouthpieces, which were made of sheet metal
formed around a mandrel, with a ring soldered around the top to form
the rim. A typical rim starts as a ring about 3mm thick, 24mm
external diameter and 18mm internal diameter and I’m wondering
whether it would be feasible to cast them using Delft clay - which I
haven’t yet used.

First of all, is this feasible? The main reason I ask is that the
instructions state that Argentium should be left to cool for a long
period in order to prevent cracking. But in videos of the Delft
process that I’ve watched the casting is immediately cooled -
presumably to avoid burning too much of the clay.

If it is possible, my next question is whether there are any
differences between the processes for Sterling silver and Argentium
that I should be aware of? For example, is it an absolute necessity
to use a graphite crucible?

Many thanks in advance,