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State of casted rings?


#1

Just recently had a few styles of rings casted. I made them all a
size 7. I have sized a few now just to have them on hand. I have
been anealing them first to be on the safe side. What state is the
metal when I get it back from a casting company? Is it annealed or is
it brittle??? (These are white rough sterling castings.) Can I anneal
them in my kiln and what temp for how long ~ do I need too?

Thanks so much for any input.
joy kruse


#2

The castings should be in an annealed state, unless the casting
house has done something novel. CIA


#3
What state is the metal when I get it back from a casting company?
Is it annealed or is it brittle??? (These are white rough sterling
castings.) 

Cast sterling silver will normally be pretty soft. Whether it’s
totally dead soft depends on what temperature the flask was at when
quenched and how slowly it cooled to get there, as with too slow
cooling, some age hardening may take place. But it should never be
brittle or too hard to do normal work with.

If you choose to anneal, you’re better off using a torch. That
allows you more freedom to apply a proper fire coat to protect from
fire scale and fire stain (already a problem with castings).
Annealing in a kiln can be done, but there’s generally no reason to
do it that way for jewelry scale castings, and since it usually
involves longer times, fire stain problems can be substantially
worse as a result. With a torch, apply a suitable firecoat, such as
Prips flux or Cupronil or Fire Scoff, etc, then heat with a torch
just to the point where a faint dark glow in subdued light is seen,
or to where a colorless or blue flame picks up bright yellow sodium
flare coloring when it hits the metal (that’s visible just a little
cooler than that faint red glow, but is hot enough for annealing.
Sterling anneals at this temperature in mere seconds, so no dwell
time is needed. Wait till any visible glow is gone (not longer) and
quench in water.

Peter


#4

Joy,

Freshly cast metal is as soft as it gets. It is when you start to
change its shape by hammering, stretching, or bending that you will
make it harder, and will then require annealing to soften it again.

Jay Whaley


#5
The castings should be in an annealed state, unless the casting
house has done something novel. 

Not really, they are in the “as cast state” which is typically softer
than annealed wrought silver. They are also have less tensile
strength than annealed wrought silver. The crystal structure is
large and dendritic there also can be porosity that makes sections
weak so stretching cast rings can be somewhat tricky when compared to
working up wrought material.

James Binnion
James Binnion Metal Arts


#6

Thanks so much. This is just what I needed to know. Seems I am always
trying to reinvent the wheel in my little studio. I will proceed as
you have instructed.

Happy making!! :slight_smile:
joy


#7
This is just what I needed to know. Seems I am always trying to
reinvent the wheel in my little studio. I will proceed as you have
instructed. 

Welcome to the club, I find I do this a lot myself, I also suspect
that a lot of the people on this list do it as well (they are a smart
bunch :wink: ).

I made a set of cocky jaws recently, and found that the pliers I’d
used as a base gave me a massive cramp in my hand.

I’ve given up trying to make a set again, but have thoughts about
making a purpose built clamp that does the same thing.

Regards Charles A.


#8

Hi James,

Not really, they are in the "as cast state" which is typically
softer than annealed wrought silver. 

I’m going to have to slap those teachers again, but I will use the
term “as cast” from now on.

Regards Charles A.


#9
They are also have less tensile strength than annealed wrought
silver. The crystal structure is large and dendritic there also
can be porosity that makes sections 

Thanks so much. This is what I was wondering. I stretched a ring on
my ring stretcher and I wanted to see how far I could push it. It
cracked and seemed more porous than what I am tradationally use to.
It had almost no resistance and then it cracked. With my forged
rings they seem to have resistance you can feel right away even if
annealed. It is just a slight difference in ‘feeling’ the metal
stretch. (Does that make any sense?) I will tumble all of these
rings and I am assuming that will work harden them slightly and
reduce some of that porosity but is it ever the same as a forged
ring?

Thanks again. I love science so I always want to know what is going
on that I can’t ‘see.’

joy


#10

Joy,

I will tumble all of these rings and I am assuming that will work
harden them slightly and reduce some of that porosity but is it
ever the same as a forged ring? 

Tumbling affects only a thin surface layer, perhaps a half
millimeter deep at best, and that’s with steel shot, not with the
tiny pins of a magnetic tumbler. They don’t do much at all beyond
surface brightening. With heavier steel shot in a decent rotary
tumbler, the work hardening that occurs is still only the surface
layer, and not to a large degree in terms of affecting the whole
ring. The main effect is that by burnishing the surface, the tumbling
allows that surface skin to be a bit more compacted and free of
obvious surface porosity, thus a better polish than what you get with
just plain cast silver. But then, only if, when polishing the tumbled
ring, you can do it without cutting through that thin burnished
layer. It’s thin enough that this can be uncertain. While such a
surface can be slightly tougher and more resistant to scuffing and
tiny dents, the overall toughness of the ring, resistance to bending
or breaking on a stretcher, or even the degree to which impacts will
cause the larger size dents, will not be significantly different from
the plain cast ring. This is not to say tumbling is a waste of time.
It isn’t. It does distinctly help, and improves the surface sometimes
quite a bit. But don’t expect it to do much more than that. It’s
still not even close to a forged ring, because 99 percent of the
silver remains in the as cast state, rather than with the tight,
uniform, small crystal structure that a properly treated forged piece
can have. There is still, as you’ve noted, a large difference.

Peter


#11
Thanks so much. This is what I was wondering. I stretched a ring
on my ring stretcher and I wanted to see how far I could push it.
It cracked and seemed more porous than what I am tradationally use
to. 

All castings are porous to some degree It depends on many different
factors as to how porous it will be. But it could be just the
dendritic as cast structure of the metal that made the rings crack.

It had almost no resistance and then it cracked. With my forged
rings they seem to have resistance you can feel right away even if
annealed. It is just a slight difference in 'feeling' the metal
stretch. (Does that make any sense?) 

Yes

I will tumble all of these rings and I am assuming that will work
harden them slightly and reduce some of that porosity but is it
ever the same as a forged ring? 

Tumbling will make no difference at all, the hard layer formed by
tumbling is only a few millionths of an inch thick. To really do any
work hardening will require a metal hammer on the cast metal with
significant reduction in cross section. This is not normally
possible with most castings.

James Binnion
James Binnion Metal Arts


#12

Tumbling will only harden the surface of cast material. It won’t help
your problem.

Judy Hoch


#13

Ok, please allow me to interject.There is no such word as “casted”.
Many students misused it during my years of teaching. You can cast.
Once it is cast, it’s cast. You can say you’re “casting” and that’s
it. Same with fishing, different context.You can cast a line, and
it’s called “casting” a line. Sorry, it drives me a bit nuts to see
improper use of words.

Margie Mersky
mmwaxmodels.com


#14
Tumbling affects only a thin surface layer, perhaps a half
millimeter deep at best, 

Not even that on jewelry scale machines and objects. You cant get
enough energy into the work. Maybe with a Centrifugal Barrel Finisher
that has a 5HP motor and your work would look like it had been beat
to death. It takes real movement of metal to get that kind of depth.

James Binnion
James Binnion Metal Arts


#15

Tumbling affects only a thin surface layer, perhaps a half
millimeter deep at best,

Not even that on jewelry scale machines and objects. You cant get
enough energy into the work. Maybe with a Centrifugal Barrel
Finisher that has a 5HP motor and your work would look like it had
been beat to death. It takes real movement of metal to get that
kind of depth. 

Jim, I based that statement on one instance recently, where I tumbled
a bunch of cast pendants. These have a milled design of almost
vertical cuts into the surface, with the cuts all too narrow for any
of the shot (imagine the lettering on a class ring…), so all the
tumbling was confined to the outer surface. In that situation, I
found the originally sharp corners/edges of the recesses to be
slightly mushroomed over, since the shot could hit one side of the
corners, but not the other. The depth of that effect was roughly half
a millimeter, or seems so to my memory. (enough to mess up the detail
on the castings, which I recast, and tumbled the next time in my
magnetic tumbler, which worked well). It was only these half
protected corners which got uneven burnishing which showed any
appreciable and noticable distortion. The rest of the surfaces were
merely nicely burnished. I think it’s the unequal distribution of
the tumbling to only one side of each corner, and the fact that the
corner shape offers less resistance to the tumbling forces than a
flat surface would do, that resulted in that degree of effect, and
would agree with you that this would not be the usual depth of the
effect on the metal.

My tumbler is fairly small, using an octagonal faceted barrel (think
of a shape something like a large single cut stone…) set an about
a 30 degree angle. It’s designed for small volume jewelry tumbling
with steel shot, not a repurposed lapidary machine, but it’s still
not an exceptionally large or powerful thing. I got it from allcraft
a few years ago (If memory serves, it was about a hundred fifty bucks
or so…), and it does work better with steel shot than previous
tumblers I’ve used.

Peter Rowe


#16

Thanks to everyone on my questions of cast rings. I went ahead and
sized them all and did not worry about annealing them. We will see
how they hold up to customer wear after they are sold over the
summer. It will be interesting to see if I get any customers need
their ring reshaped after wearing it a short while. Also did not
realize how thin a layer tumbling affected. Thanks again :slight_smile:

joy Web:


#17

There have been several recent studies on tumbling jewelry with
steel shot that measured actual hardness and depth of hardness. It
is really so thin that mild polishing will remove it.

http://www.ganoksin.com/gnkurl/m0

James Binnion
James Binnion Metal Arts