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Silver won't flow


#1

Hello, I’ve been reading the in the archives for some
time now. I am fairly new at jewelry making and want to start
casting. Here’s my problem:

I am melting silver in a prepared crucible with a borax, boric acid
flux (dry). It seems to take inordinately long and then invariably
I end up with a ball of silver that will not flow. I’ve tried a
number of different methods, but this is always the result. What am I
doing wrong?

Any help will be greatly appreciated. I’ve read everything I can
find, but it seems from what I’ve found that I’m the only person for
whom silver does not just melt and flow. Can this be true? Thanks so
much for any

Kind regards,
Barbara O’Neill


#2

Barbara,

You didn’t say how much you are trying to melt and with which tools.
But in general, make sure you use enough heat. Use a larger sprout if
needed. The silver will be ready for casting if you get a
"dancing"-like effect on the surface.

Try it with a smaller amount to test it.

Alain


#3

Barbara, what type of melting torch are you using? Sounds like your
heat source is inadequate. You may want to try using a oxy/propane
setup with a rosebud tip.

Best wishes,
Ken Sanders


#4

What type of torch are you using, and with what fuel? How much
silver are you attempting to melt?

Talia in Kansas


#5
       Any help will be greatly appreciated.  I've read everything
I can find, but it seems from what I've found that I'm the only
person for whom silver does not just melt and flow.  Can this be
true? 

No, it can’t be true. Silver doesn’t melt or refuse to do so based
on the person attempting it. it does it based on whether it’s hot
enough, or not.

When silver melts, it first gets rather slushy, and in that state
pulls together into a “wet” mass that may look fully melted, being
liquid on the outside and especially on the top. but at that point,
the top, where the torch hits, may be molten, but most of the mass is
still slushy or even solid at the bottom where it’s chilled by the
crucible.

You simply need to heat it hotter. it will be ready to cast when
the surface of the metal is not only wet and molten, but is
"spinning", and the whole mass of metal in crucible is easily fluid
and moves and flows around the crucible easily. To get there, you
probably need the silver to be a good hundred degrees or more hotter
than you’re currently getting it.

You don’t mention what type of torch you’re attempting to melt the
silver with, nor how much silver you’re attempting to melt at once.
You may simply need a bigger or hotter torch. Another thing to watch
is what sort of surface the crucible is sitting on. Put the crucible
on a soft fire brick, charcoal block, or soldering pad, or some other
insulating surface so that surface doesn’t draw too much heat from
the bottom of the crucible. And, you may find it useful to preheat
the crucible thoroughly before you place the silver in it.

Be sure the entire mass of silver is fully covered by the torch
flame, be sure the flame is reasonably gentle and not oxidizing but
otherwise still good and hot, and be sure the metal stays clean and
oxide free by using a bit of boric acid, or a mix of boric acid and
borax powders, added to the top of the silver as you start to melt,
and a bit more added during melting if it looks like the surface is
oxidizing, or anything other than clean and bright.

Peter


#6

Barbara, If your silver won’t flow it’s not hot enough. I assume you
want to pour it into an ingot mold or some such. If so, you need to
get it hot enough so that the survace is shiny and shimmery. You
should have a fairly bright ring around the metal when you pour.
Since you say it’s taking a long time to ball up, it sounds like
your torch is too small for the amount of metal you are trying to
melt. That will also happen if the gas pressure is low.

Jerry in Kodiak


#7

And, I would add, is your crucible properly seasoned? And re your
silver; is it “new” stuff, or scrap that might possibly have some
solder in it?

Margaret


#8

Gosh I’m not sure but I remember reading that if your silver gets so
hot that it starts “a dancing effect” that means that you have over
heated it and it is rapidly absorbing Oxygen and other gasses which
cause porosity, and alloy separation as well I cast small amounts 20
to 40 ounces of silver a day 2 to 4 times a week and the only time I
notice any movement in my metal is when I pour from a melting dish
into the Crucible of my caster and the metal contacts the flux while
the metal is nearly at flow temperature and the flux is still cool,
remember that Melt temperature and flow temperature are different,
and different alloys of sterling have different liquidous temps.

Too hot and liquidous turns gaseous remember the physical states of
most things are solid, liquid and gas or vapor and these are all
associated with temperature, Not necessarily in order actually some
are solids at very low temperatures and liquid and then watch out, as
in the case of these that are normally in a gaseous state Oxygen and
Nitrogen come to mind right off.

I use a very large Oxy Acetylene torch with a quite large Rose bud
(multiple Orifice tip) but if all you are getting is a ball of semi
molten silver then you aren’t getting your metal hot enough, once it
gets hot enough the surface tension breaks down and it will flow
into a flat top puddle that will offer minimal resistance when
stirred with a carbon stirring rod, it will feel nearly as though you
were stirring something slightly thicker than water, and the surface
will be shiny and wet looking if the flux is working for you. But it
won’t be dancing for you.

If I’m using Deoxidizing grain I use Boric Acid it won’t flow with
the metal, it will stay primarily in the crucible if you use a bit
too much, Borax will flow with the metal and leaves holes when
pickled, If I’m using traditional copper based alloy then I’ll use a
PH Neutral flux like Matt’s casting flux, but sparingly, it will flow
into the mold cavity if you get carried away, and leave the nasty
large holes when pickled, Do not use a PH Neutral flux like Matt’s
casting flux if you are using Deoxidizing casting grain Not
recommended by several refiners and suppliers I tried it any way and
got a high rate of very tiny surface porosity,(occasionally suppliers
know what they are talking about)

Kenneth Ferrell


#9

In the interest of fairness to anyone having trouble melting silver
for casting, I will admit to an embarassing bit of my own history. I
have managed to turn perfectly good silver into a black-and-white
spongy brittle mass that had to be thrown out. I was using a large
oxy-acet. torch-- plenty of heat. I assume that I oxidized it all to
hell. I don’t really know. However, I never did that when using a
smaller torch, so maybe I just fried it. Bottom line, it isn’t just a
matter of hot enough or not. I’ve also covered my silver totally
black with soot. So getting the flame right is pretty important, too,
especially (I’m guessing) with dirty acetylene. This confession will
not solve anybody’s problems. My goal is just to let any other
melting-klutzes out there that you’re not alone. Hi, my name is Noel
and I’m a melting-klutz… I’ve been clean for two years…

–Noel Yovovich


#10

Barbara, It is quite possible you are not heating up your crucible
enough prior to melting the silver and as a result when you try to
pour the temperature of the silver drops and returns to the solid
state. Joe Dule