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Using buttons and sprues in casting


#1

As I do a lot of casting I have accumulated a batch of sprues and
buttons, and would like to use them in casting new items. I know
that I must add at least 50% fresh metal for each cast.

However, I wonder if I should convert the sprues and buttons to
grain. Or should I just put them in the crucible, and as they are
large, get them almost molten, and then add fresh metal and continue
to melt them together.

If it is better for me to convert the sprues and buttons to grain,
what is the proceedure. I know that I should melt them, then plunge
them into a bucket of water. However, how close to the water should
I bring the crucible before pouring the metal? I have had
conflicting advice. Some suggest pouring from a distance of about 2
feet. Others had told me to bring the crucible right up to the water
and then pour.

I am concerned about the safety of this process, and will appreciate
your help.

Alma


#2

Hi Alma

You have said quit a bi, t but there is much more that needs to be
known.

What type of metal, Gold, Silver or bronze?

What kind of furnace do you have, or is it torch melted? How do you
monitor Temp?

Do you have a protective atmosphere? How deep is your graining tank?

Do you plan on using flux? Is your crucible self skimming?

I could think of more questions for a better answer.

This is why people turn in there gold and get fresh.

It is worth a shot if you don’t have the time though.


#3

Hi Alma,

The biggest issue with buttons is to make sure they’re clean. No
investment. Anywhere. No flux either.

I’ll normally chop the sprues off with a bolt cutter, to make it
easier to fit them in the crucible later, and do make it easier to
clean them. They also usually take a spin through the sand blaster,
or at very least an ultrasonic, to blast off as much surface crud as
possible.

Chopping them up also makes it easier to make your weights. A single
100gm button is harder to deal with than a 50gm button, and a bunch
of nice, bite-sized sprues that can be thrown in anywhere.

I don’t normally pre-melt the buttons. I just put it all in the
crucible together, and bring it all up to temp. Concentrate on the
button, as it’s biggest, but it shouldn’t be that big of a deal.

As far as graining goes, don’t bother. If you want to, I’ve had good
luck dropping from waist height into a 5 gallon bucket of swirling
water. Ended up with what looked like silver popcorn, rather than
beads, but it broke the quantities up into nice manageable units. I
wouldn’t get a hot crucible anywhere near the surface of a water
bath. Seems karmically unwise.

Regards,
Brian


#4

Hi Alma,

I just add my cleaned buttons and sprues along with scrap.925 silver
to the rest of the metal in the crucible and go ahead and melt. In my
gas fired crucible furnace they all melt at more or less the same
time. Usually the rest of my crucible mix is fine silver casting
grain and sufficient copper to alloy to a touch above.925 to ensure
that the melt is at or above .925.

Cheers
Jen


#5

Thank you all for the excellent suggestions on using my buttons and
sprues in casting. As I would be melting them with my torch in the
crucible of my Neycraft centrifuge, it will take some time to get
them all melted. In additiion, I would have to spend time getting
them clean and free of all investment. Also, making shot does not
seem feasible, so I have decided to take them to the local refinery,
and trade them in for fresh casting grain.

Time is of the essence. I just finished one show, and now am busy
preparing for two more. I just have to budget my time. So thanks
again for your help. Alma