...how I can support rings for firing so they can stand up?
I’m a real beginner with enameling, but I have done some with
soldered joints involved. It seems improbable (at least to me) that
1540* solder would draw into a joint when fired with soft fusing
enamels at 1325*, but I guarantee you that it does that for me.
Perhaps the solidus is lower than 1325, I don’t know. But your
soldered joint may be less solid than you think. Especially if your
’enameling’ solder flows at 1460 or 1490 and you are firing in the
1400’s. (You can get 1540 enameling solder from Otto Frei).
Anyway, if you don’t get a reply with better ideas, try making a
fairly dense nest out of stainless steel binding wire and embed the
ring in that, or carve out a magnesia block so the ring fits nicely
in it with the top well exposed to the heat. The magnesia block
method has worked well for me. The blocks do get weaker with
repeated use so handle them gently.