Silver Casting

I have been thinking of casting a chalice in sliver in addition to making
some broach-like settings. I am set up to do sand casting and can probably
finish the stuff off in the machine shop.

I have a number of 100 oz ingots of .999 bulion to play with but suspect
that one does not want to use pure silver for this sort of stuff.

Can someone provide me with some alloying info to get something like
sterling?

Is this really necessary?

js

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On Fri, 16 Jul 2004 07:40:57 -0700, in ¤ô Jack Schmidling wrote:

I have been thinking of casting a chalice in sliver in addition to making
some broach-like settings. I am set up to do sand casting and can probably
finish the stuff off in the machine shop.

I have a number of 100 oz ingots of .999 bulion to play with but suspect
that one does not want to use pure silver for this sort of stuff.

Can someone provide me with some alloying info to get something like
sterling?

Is this really necessary?

js

Recent threads suggest that it's pointless for us to suggest that sand casting
an item of this size may be less successful than you hope, given that silver is
more prone to problems with shrinkage porosity than some of the other metals you
might be sand casting. But if you use plenty of sprues (or gates, if you like),
and the thickness of the chalice you use as the model is not too thin, you might
get sucess. And of course sand casting is easy enough to try over and over till
it works, at little expense other than the silver itself, so I'd say, "go for
it". Not much to lose if you've already got the setup. Sterling silver melts
at around 1640 F, and you'll want it around a hundred degrees hotter than that
to pour, I'd guess... Be sure to use some boric acid powder or a mix of boric
acid and borax, as a melting flux, to help control oxidation when you melt.
Thin sheet metal forms will be difficult to get to fill well, unless you have
the metal at a seriously elevated temperature when you pour, which can increase
problems with porosity. But if you've already got the setup, then it's easy
enough to try, and of course, any silver scrap you generate can easily enough be
remelted, or sent for refining.

The alloy normally used as sterling silver is 7.5 percent copper, with the
balance being pure silver. Be sure to use good pure copper as the copper
source. i've always used scrap copper electrical wire, which works just fine.
If you want to get fancy, there are proprietary silver alloys out there which
use other than copper, in order to reduce fire scale/oxidation problems on the
silver when casting. These tend to produce a softer alloy than sterling, but
may be worth investigating. I don't know if they are available as "master
alloys which you'd add to pure silver. suspect not, but worth asking. United
Precious Metals is the main supplier I'm aware of for these alloys. As I said,
the exact formula for them is proprietary, so I can't give you that composition.

Hope this helps, and have fun. let us know how it turns out, will you?

Peter

"Peter W. Rowe"

and the thickness of the chalice you use as the model is not too thin,
you might
get sucess.....

I would not have given it a thought until I saw the goblet I bought on ebay.
It is from Spain for what that is worth but very thick and a really nice
feeling cup. I don't think there would be any problems casting it in sand
other than the usual take 2, 3, etc till getting it right.

If I had the notion at the time, I could have used it for the pattern but
now it has rubies all over it.

The alloy normally used as sterling silver is 7.5 percent copper, with the
balance being pure silver.....

That sounds easy enough but the other question was, do I need to do this?
Would pure silver present any problems?

js


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Jack Schmidling wrote:


That sounds easy enough

Just do it, ... and you'll find out how "easy" it is.

Abrasha
http://www.abrasha.com

"Abrasha"

That sounds easy enough

Just do it, ... and you'll find out how "easy" it is.

I was referring to the formula for sterling.


Adding 7.5% copper to molten silver does not sound like much of a challenge
either.

As far as the whole project is concerned, I have made silver, aluminum and
brass bells just a little smaller than this and the only problem I had was
with the handle so I cast it separately and soldered it on later. I was
planning on doing this with the stem/base of the cup also.

js


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On Sat, 17 Jul 2004 00:19:11 -0700, in ¸ô Jack Schmidling wrote:


Adding 7.5% copper to molten silver does not sound like much of a challenge
either.

Rather than melting the silver and adding solid copper to it, just put both
together, cold in the crucible, with the copper on the bottom (to limit
oxidation), and melt both at the same time. You won't then need it to get
quite as hot, as sterling melts at a lower temp than either fine silver or
copper.

Peter

Going down the casing route is good thinking on your part in view of
the soldering problems you have had with fabricating your chalice the
traditional way.
Sand casting will give a most unusal texture to the surface, and using
100 oz of silver would definatelly qualify the chalice for the guiness
book of records.
Would your mantle shelf be strong enough to take this size and weight?
I can easily imagine a gallon of wine in it. Certainly nice to use.
the other option would be to cast a cylinder from the silver, then
turn the whole chalice up in a lathe. Fine silver turns very well.
that way you would achieve the shape and size without any soldering atall.
good lateral thinking.
Youll find using pure silver a much better option to the traditional
sterling .
Ive used it a lot . I had a comission many years ago to make some
paper weights in pure silver. these were 3in in dia by 1in thick. I
recessed the top and fused clear enamel therein 1/4in deep then floated
paillions of fleur de 'Lys on the enamel. . fired them in a kiln till
the siver just started to melt. wonderful effect.
Fine silver doesnt get fire scale like the 925 alloy. To answer your
last question it isnt neccessary at all to alloy silver nor alloy gold.
Pure silver has the most beautiful white colour. When you see sterling
along side it theres no comparison. Same with gold. It has the
loveliest yellow of all metals.
as Peter our moderator has said we look forward to seeing the results
of your continuing efforts.
theres no doubt youll get the results you seek in the end.
All our support for your efforts.
Making broach settings are easier done by hammering the silver into a
die. the bigger the hammer the better. My biggest hammer is 275 lbs.
Takes some handling. I now use this minting technique a lot to make
items of jewellery. Its also easy to make money this way. Id have no
problem making 1pound coins (UK currency) but the trouble is they cost 2
pounds to make. Once the tooling is made(the expensive bit) the
production costs are nominal. Ill give some thought to making a chalice
this way, could be a new development.

Jack Schmidling wrote:
I have been thinking of casting a chalice in sliver in addition to making
some broach-like settings. I am set up to do sand casting and can probably
finish the stuff off in the machine shop.

I have a number of 100 oz ingots of .999 bulion to play with but suspect
that one does not want to use pure silver for this sort of stuff.

Can someone provide me with some alloying info to get something like
sterling?

Is this really necessary?

js

"Ted Frater"

Going down the casing route is good thinking on your part in view of
the soldering problems you have had with fabricating your chalice the
traditional way..

You know, if you unfriendly types would read my message instead of reacting
to my name, things would be much more pleasant.

I had not problems fabricating a chalice as I never attempted to fabricate
one and never implied that I wanted to. I bought 6 of them on ebay which
gave me plenty of stuf to futz around with.

Sand casting will give a most unusal texture to the surface....

That's why someone invented the lathe. Sand is more than adequate for
anyone other than a Troglodyte whose most sophisticated tool is a hammer.

and using
100 oz of silver would definatelly qualify the chalice for the guiness
book of records....

Who said anything about using 100 oz for the cup? I said I have a number of
such ingots. Is it not possible just to use some of it?

Certainly nice to use.
the other option would be to cast a cylinder from the silver, then
turn the whole chalice up in a lathe. Fine silver turns very well.
that way you would achieve the shape and size without any soldering atall.
good lateral thinking......

Duh! But why not cast it close to the final shape and save a lot of
hogging?

Youll find using pure silver a much better option to the traditional
sterling .....

Ah.... finally something useful.


Fine silver doesnt get fire scale like the 925 alloy. To answer your
last question it isnt neccessary at all to alloy silver nor alloy gold.
Pure silver has the most beautiful white colour. When you see sterling
along side it theres no comparison......

So what is the point of sterling? Surely not to save a little silver.

Making broach settings are easier done by hammering the silver into a
die. the bigger the hammer the better.....

Where does one get the dies? I can't even find decent broaches.

Ill give some thought to making a chalice
this way, could be a new development.

You might need a real man's hammer for that one.

BTW, one of my neatest cast projects was a whole set of nuts as in the
bowlfull around Christmas time. I used the real nuts (walnut, Brazil,
peanut, pecan, almond, etc as the patterns and cast them in pairs. I also
made a small bowl to hold a complete set. Also put them on key chains and
gave them as gifts. We made them in silver, aluminum and brass and won the
blue ribbon, best of show and $100 at the only art fair I ever went to. We
called the display Aluminart. Funny thing was, while we wowed the judges,
we did not sell a single piece. That was 20 years ago and now the melting
furnace is more commonly used for brewing beer but every once in a while I
get the urge to melt something.

js


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On Sat, 17 Jul 2004 00:19:15 -0700, in Ìô Jack Schmidling wrote:


You know, if you unfriendly types would read my message instead of reacting
to my name, things would be much more pleasant.


In this instance, Jack, I think Ted was attempting a bit of satirical humor,
not insult. He's impressed by the scope/scale of your projects. Most
newcomers are happy if they can manage, with much help, to cast a small thing
like a ring. Though I understand you've had prior sand casting experience,
perhaps Ted missed that. For a beginner, just jumping into casting something
the size of a chalice is rather more than a normal beginning task.

Again, I'm reminded of the old adage/definition, which states that experts are
the guys who know all the very many reasons why a thing is impossible, or
should not be done. Meanwhile, an amateur is the guy who, not knowing a thing
is impossible, goes ahead an naively does it...


Sand casting will give a most unusal texture to the surface....

That's why someone invented the lathe. Sand is more than adequate for
anyone other than a Troglodyte whose most sophisticated tool is a hammer.

now now. Be nice. Actually, hammer work is capable of far greater delicacy
than you can get with casting, even high tech methods other than simple sand
molds. For one thing, wrought silver, has a much finer crystal structure
without the pores and defects common to castings. The result is denser metal
that's much stronger, harder, and will take a much higher level of polish. All
the best holloware is made either by such methods, or on the commercial level,
via spinning lathes which also start with rolled/milled sheet metal and form it
to the desired shape by deforming, compressing, and otherwise working the metal
the way hammers do. It's also a good way to build up strong wrists and arm
muscles, as well as a good way to drive everyone in the neighborhood quite mad
due to the noise... And with hand raising (as the process of developing such
forms with hammers and stakes is called), you're not limited to the shapes one
can turn on a lathe. ovals, varied faceted forms, and completely free form
assymetrical forms are all possible.


Who said anything about using 100 oz for the cup? I said I have a number of
such ingots. Is it not possible just to use some of it?

Certainly nice to use.
the other option would be to cast a cylinder from the silver, then
turn the whole chalice up in a lathe. Fine silver turns very well.
that way you would achieve the shape and size without any soldering atall.
good lateral thinking......

Duh! But why not cast it close to the final shape and save a lot of
hogging?


Again, Ted strayed into the realm of humor...

Youll find using pure silver a much better option to the traditional
sterling .....

Ah.... finally something useful.


Fine silver doesnt get fire scale like the 925 alloy. To answer your
last question it isnt neccessary at all to alloy silver nor alloy gold.
Pure silver has the most beautiful white colour. When you see sterling
along side it theres no comparison......

So what is the point of sterling? Surely not to save a little silver.


Actually, this can be open to opinion. While fine silver has a white color,
and is not prone to the oxidation problems of sterling silver, it is
considerably softer. This softness, which makes many thinner forms impractical
to make or use, is the big disadvantage of fine silver. for example, you might
make a chalice via casting that might have a fairly delicate looking stem.
With sterling silver, that stem could be thinner, and still have enough
strength, while in fine silver, it would not be hard to make a stem that looks
nice but would be prone to bending when used. In the case of Ted's die struck
items, the work hardening of the striking process makes the silver quite hard
enough to hold up. but a fine silver casting will be fully annealed. That
will be a very soft piece of metal, compared to the same thing in sterling
silver.

Making broach settings are easier done by hammering the silver into a
die. the bigger the hammer the better.....

Where does one get the dies? I can't even find decent broaches.

Ted actually does something here most craftspeople don't do. he uses die
striking, via high pressure presses, or the old style of drop hammer (when he
refers to a 275 pound hammer, it's not one with a handle that you lift with one
arm, or even a normal sledge. it's likely a 275 lbs steel striking form that
drops in a frame to hit a die set mounted in the base. Making the dies is
the tool and die makers art. Generally one does not buy them, unless one gets
lucky and finds what is needed in some old defunct manufacturers stock, or on
ebay where such antique dies may be sold, etc. Gold machinery in providence
R.I. has bins and bins of the old dies. Commercially, these days, much more
work is produced by lost wax casting. (in investment, not sand. investment
looks a lot like plaster, but takes high temps, and produces much smoother
castings that you get with sand.)


Ill give some thought to making a chalice
this way, could be a new development.

You might need a real man's hammer for that one.

his 275 lb drop hammer would do it. Take a weight of that size, and drop is
from a height of, say, five or six feet. Calculate the energy imparted at
impact. It's quite a lot... Note that larger foms might be developed using a
sequence of progressive dies, not just one single strike.

"P.W. Rowe, moderator, r.c.j." wrote in
message ...

Making the dies is
the tool and die makers art. Generally one does not buy them, unless one
gets
lucky and finds what is needed in some old defunct manufacturers stock, or
on
ebay where such antique dies may be sold, etc.

There's a guy on the re-enactment scene in the UK who is making coin dies
for historic coins, all marked so that collectors know that the resultant
coins are modern copies.

He's charges reasonably low prices for his dies, less than £120 (about
$200) last I heard.

--
William Black
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Strange women lying in ponds distributing swords
is no basis for a system of government