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How do you melt silver coins?


#1

I received a terrific gift - several .999 silver coins for the
express purpose of my jewlery-making! But, how do I go about the
process of melting them down? I know, of course, that I’ll use my
acetelyne torch, but how do I get it to a flat sheet with consistent
thickness? And, is there a way that I can get it to, say, 26 gauge?

Dori


#2

If you really want it in such a form, how about just running the
coins through the rolling mill?

Margaret


#3

Dori

  1. Heat source
  2. Crucible to melt it in
  3. ingot mold
  4. Rolling mill

Torch you have

Crucible, could be a lot of things, most common is the ceramic type
for melting with a torch. Condition before use, i.e. coat with flux
first and melt.

Ingot mold can be steel or a carbon block, just something to hold
the shape of a basic plate form.

Rolling mill, make sure that your ingot is not thicker than what
your mill will open to. Could hammer it down, but boy would you be
along time, on the bright side, you would be an expert with a hammer
after word.

Anneal often to keep your plate from cracking.

Alternative - get wax, a bar of soap piece of wood and carve to a
design you want and then with cuttlefish bone press a mold into the
surface and pour what you want.

I just hit the highlights of course, read the archives for specifics
and additional alternatives.

Terry


#4

Dori:

I wouldn’t recommend acetylene as a good gas for doing ANY work on
silver: it combines chemically with silver when at high
temperatures. This is the primary cause of fire scale in silver and
its alloys. Also, you should add the precise amount of copper needed
to make the 999 fine silver into sterling silver, as pure silver is
just too soft to make jewelry. As for making it into sheet, a flat
rolling mill will do what you need. If you don’t have propane or
natural gas or a rolling mill, take it to a jeweler who does and
have them alloy, pour, and roll it into sheet.

Chris


#5

buy a crucible and tongs
buy some borax flux
season the crucible with the flux
cut your coins into smaller pieces
add to crucible

melt (looks like a rolling ball of mercury-waer saety googles with
tinting, or welders glasses)

pour into greased and warmed mold- buy one or use a charcoal block
that you have carved a long flat rectangle into-(use a stainless
steel ruler and pull it /scrape to the depth of the gauge you want,by
marking it on the ruler with a sharpie and then add a couple of mm’s
for safety).warm the charcoal periodically while melting to prevent
the metal “jumping” out of the charcoal to get the best results you
can hope for,without a mold.

air cool until grey then water quench

forge it on a highly polished anvil or bench block if you don’t have
access to rolling mill otherwise invest in a rolling mill all, in all
you are looking at about near 220.00 to melt and roll out your
coins…

better to send them to a refiner, get the credit for the.999Ag and
then buy sheet,prefabricated with it if you don’t have the euipment
already to go…

R.E.Rourke

(another tip: read Tim McCreight’s book “the complete
Metalsmith”-everything you need to know is in there…and more.Most
libraries have a copy of at least the 1st edition, or its available
from Bryn Mawr Press at about 18 bucks for the most basic edition )


#6
I wouldn't recommend acetylene as a good gas for doing ANY work on
silver: it combines chemically with silver when at high
temperatures. This is the primary cause of fire scale in silver and
its alloys.

Fire scale is a copper oxide in the silver copper matrix and does
not form in fine silver. And is caused exposure to oxygen at high
temperatures not acetylene.

James Binnion
@James_Binnion
James Binnion Metal Arts


360-756-6550


#7

A very labor UNINTENSIVE methoid would be to trade the coins in to a
precious metals refinery for wire, sheet metal, etc. Most refinery
are glad to trade. But do you have enough to make the trade
worthwhile, as there is usually a fee. Or you can buy a few thou of
equipment and do it yourself. Letting a refinery do the grunt work
seems like a more efficient method to me. I personally think that my
time, spent rolling, pulling, etc… is quite a bit more valuable
than the miniscule fee they charge. I’d rather spend my time
producing finished pieces than producing raw material. Casting is
the same. I send my waxes to a casting co. in Pennsylvania(an Orchid
member) that charges aprox $10 labor plus material. Unless you are
willing to work for 50 cents per hour, it seems like the best way.

Ed in Kokomo


#8

Wow, Dori, what a wonderful gift.

First off, many of us use acetylene with silver as the tool of
choice for most work. There is no problem with it. If you get a
little firescale or fire stain (from overheating), there are several
tried-and-true ways to remove it, such as adding hydrogen peroxide to
your pickle and/or sanding. Acetylene/air torches are pretty much the
standard in many schools for teaching beginning silversmiths;
additionally, most of us have the torch we learned on as our “old
faithful” in our shops, so there are a lot of silversmiths out there
using acetylene.

Having said that, there is no reason to melt those coins unless you
really want sterling! Use a rolling mill to roll them out to whatever
gauge you want. If you want a hint of the design (which can be a cool
and almost abstract effect once rolled to that thinness), then just
anneal and roll. Otherwise, you can use a file or grinding wheel to
knock down the highlights on the design (you don’t have to remove it
all, just hit the high points) and start rolling. You’ll need to
anneal several times to get it done.

Keep in mind that fine silver is not going to ever harden as much as
sterling, but it’s still WAY harder than 24K or 22K gold. If you’re
using it judiciously in your designs, it’s a truly lovely component.
And if you draw or mill it into wire, it can be a lovely chain, as
well.

Enjoy and don’t let it intimidate you. You’ll learn a lot about the
working properties of the metal by just working those coins down.

Karen Goeller
No Limitations Designs
Hand-made, one-of-a-kind jewelry


#9
I wouldn't recommend acetylene as a good gas for doing ANY work on
silver: it combines chemically with silver when at high
temperatures. This is the primary cause of fire scale in silver
and its alloys. 

In fact acetylene is perfect for silver whether it be sterling or
fine. Acetylene does not cause fire scale, improper preparation of
the sterling causes fire scale. Prips flux properly applied
(discussed hundreds of times on Orchid) works 100% of the time to
prevent firescale on sterling. We have been fabricating and repairing
silver of all sizes and types (as well as gold) for 28 years. In
fact, all local jewelers refer their silver repair customers to us
because we know what we are doing. Darn acetylene!

Gary
Janine’s Jewelry
Redding, Ca.


#10

in addition to all the good comments about this topic I would like
to add a few recommendations:

Most novice jewellers forget to preheat the glazed (seasoned)
crucible to orange glowing colour before adding the metal and
additional borax powder. It is very important for silver casting as
the alloy is very reactive when molten (also Silver/Copper crystals
grow larger). Extended heating can result in cracks when rolling
therefore cast your metal without hesitation into the preheated
ingot. You should see a mirror like glow on the surface. Before
casting move your crucible around to make sure that there are no
silver lumps hidden under the surface. Silver can be reduced by
rolling up to 50% before annealing again. If you draw wire you need
to anneal it earlier (when it starts breaking). Again: keep your
annealing time short and avoid too frequent annealing. Use the
largest possible flame for the job. Having used Hydrogen/Oxygen,
Acetylene/Oxygen and LP Gas I prefer to use a straight LP Gas torch
(no oxygen) for silver work to reduce fire scale. Find some more
hints onour webpage:

http://www.planert-jewellery.com.au/soldering_hints.htm

Martin & Dorte Planert
www.planert-jewellery.com.au


#11

I would not alloy the fine silver coins. Use them as they are. I use
fine silver in making jewelry that will not be subject to heavy
wear—pendants, earrings, pins, etc… as it does not tarnish. I also
use fine silver for enameled pieces.

If you do casting you will be pleased to know that fine silver casts
beautifully. One way is to just cut the coins into small pieces. to
make them easier to melt. Be sure to keep the flame of the torch on
the fine silver as you pour it into your mold. Fine silver seems to
freeze faster than sterling.

Alma


#12

Odd, most jewelers and schools teaching metalsmithing use acetylene
with quite satisfactory results. My own caveat being that the metal
is prepared correctly.If not, then one sees fire scale to the point
of blackness (= Ag2S) or sulphur and sulfides namely silver sulfide
and hydrogen sulfide attacking and permeate the surface leaving
tarnish and similar compounds to discolour the metal as occurs in a
normal atmospheric reaction requiring no heat. From many years ago
the 19th century experiments of Messrs’s…M. P. E. Berthelot and L.
J. G. Vieille made clear the reaction upon the explosion of acetylene
and precious metals and found that if liquid acetylene was contained
and heated to a high temperature by a platinum, or fine gold wire
raised to a red heat, the whole mass decomposes and gives rise to
such tremendous pressures that no cylinder can contain the mass of
metal or the gases hovering above the metals…but that was
contained,. You are asserting that this combining happens in an open
atmosphere, as in general soldering.

I am having a hard time finding any evidence or reference that
validates that acetylene gas “combines” with Ag in the solidus or
liquidus states ( as it certainly does not combine in the solid
state) even in the acid based field of coordination chemistry, or
other fields that have no bearing on jewelery making. However there
is much to support that silver is insoluble in gases in open
atmospheres/ hand crafted jewelery making that is not cast with gas
covered furnaces assisting.Gold or platinum also do not combine with
any gases at normal or elevated temperatures. Could you give me a /
the citation, as I would like to read about the 2 states of matter
combining when a precious metal reaches the liquidus state, or
approaching [those] temperatures-, say any point between flowing
flux,solder to about 2162 C (or the boiling point of silver ) for
instance.

Thank you, R.E.Rourke


#13
From many years ago the 19th century experiments of Messrs's..M. P.
E. Berthelot and L. J. G. Vieille made clear the reaction upon the
explosion of acetylene and precious metals and found that if liquid
acetylene was contained and heated to a high temperature by a
platinum, or fine gold wire raised to a red heat, the whole mass
decomposes and gives rise to such tremendous pressures that no
cylinder can contain the mass of metal or the gases hovering above
the metals...but that was contained,. 

Silver, copper and mercury will combine with acetylene at room temp
and atmospheric pressure to form acetylides of those metals (Ag2C2
or Cu2C2. These compounds are very unstable and will explode if
shocked. This is why copper pipe and silver brazed joints are not
allowed for use in transporting acetylene gas. However the rate of
production at room temp and pressure is very low and is certainly not
an issue when using a torch as the acetylene is converted to carbon
monoxide and hydrogen and then to carbon dioxide and water vapor by
the combustion process and never reaches the workpiece as acetylene.

http://www.msha.gov/Accident_Prevention/Tips/acetylenegas.htm


http://ctea.ca/AcetyleneMaterialSafetyData.htm

James Binnion
@James_Binnion
James Binnion Metal Arts


360-756-6550


#14

Hello Orchidland,

This is a related question to responses that suggested rolling out
the silver coins instead of melting them and forming ingots.

If I have a one ounce 24K gold coin and want to roll it out, does it
need to be annealed periodically??? We’re talking pure gold here,
which is supposed to be very ductile.

Voices of experience, please respond,
Judy in Kansas


#15
If I have a one ounce 24K gold coin and want to roll it out, does
it need to be annealed periodically? 

It is ductile in nature but you need to annealed periodically
otherwise edges will be cracked.

Pavan


#16

Hi Judy,

I don’t anneal my 24k when rolling it out to the thickness I want. I
do anneal it after I have reached the thickness I want and before I
use it. Usually for me this involves using it to laminate onto silver
and I find it easier to get the gold to conform to the silver surface
I want to put it on when it is dead soft. I am not using coins but
what my supplier calls “mini bars”

Hope this helps
Doug Frey
www.dfrey.com


#17

any metal hardens when going through a rolling mill and requires
periodic annealling.

R.E.R.