I’m reposting this because it never turned up after my initial
posting. Forgive me if this is a repeat.
Hi all. I’m relatively new at this jewelry making stuff so the
following incident which I think is a bizarre situation might
seem pretty common to many of you. Well, here goes. I had a
gold ring cast at Ampex in NY. Was doing some filing and
polishing work on it prior to setting the stone. Placed it on a
metal mandrel to check size. It felt like it was stuck on the
mandrel so I just manipulated it with my fingers, twisting it
around to loosen. Well, when I slipped it off, it had fractured,
or should I say split in a ragged way in the same spot the sprue
had been. I’ve soldered it shut and it looks fine. You’d never
know. But I’m curious as to why this would happen. Are my
fingers that strong (I tore gold with my bear hands 
)? Could
there have been hidden porosity? What exactly happened here?
Thanks in advance. RD
Hi all. I’m relatively new at this jewelry making stuff so the
following incident which I think is a bizarre situation might
seem pretty common to many of you. Well, here goes. I had a
gold ring cast at Ampex in NY. Was doing some filing and
polishing work on it prior to setting the stone. Placed it on a
metal mandrel to check size. It felt like it was stuck on the
mandrel so I just manipulated it with my fingers, twisting it
around to loosen.
Well, when I slipped it off, it had fractured, or should I say
split in a ragged way in the same spot the sprue had been. I’ve
soldered it shut and it looks fine. You’d never know. But I’m
curious as to why this would happen. Are my fingers that strong
(I tore gold with my bear hands )? Could there have been
hidden porosity? What exactly happened here?
Thanks in advance. RD
Hi,
It’s probably ‘suck-back’. At the point of spruing, with no
reservoir present, the metal can chill quickly. This happens
from 1.)Not enough metal for an adequate sprue, 2.) Too cold of
a melt/not hot enough mold.
Skip Meister
NRA Endowment and
Instructor
@Skip_Meister
08/03/9723:28:50