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Casting with copper


#1

I am trying to collect on casting copper. I was wondering
if anyone has any experience in this or any ideas about this. I’m
kind of new to orchid so I’m sorry if this is not quite how it works.


#2

Dear Brenan, I don’t think you can cast with copper or I would have
done it. I had pretty good luck casting 50% copper and 50% silver,
but I think I overheated the last batch and it was porous. Copper at
high temps does not flow well. I think you are risking anything you
attempt to cast with it. It will be interesting to see if anyone
else has a solution.


#3

Hi Brenan & Welcome to Orchid

It just so happens that where I am a guest lecturer (Cal. College of
the arts-formerly CCAC) one of the seniors has been doing this as
her main project/thesis…

What I have learned from her is:

  1. Cut your metal up into tiny pieces…

  2. When placing into the crucible do it in 1/3 increments…Meaning
    put in the first batch, melt, add the second batch, melt and then
    the last batch & melt…

  3. Use lots of flux–borax.

  4. It will melt longer than it takes for a bronze melt.

  5. Set your casting machine arm/wind up for a longer spin out.

  6. Cool down to dead cold,and then quench.

  7. And of course, keep a separate crucible for your copper castings
    and use high grade copper…

*** Your surface will be rough…We have used copper for our organic
castings & this texture issue is really a non-issue. ***

Guess you would say I’m an older pooch who is still learning new
tricks!!!

P.S. We have even been casting aluminum, successfully…

P.P.S. Another mention of a great show that John & I are pleased to
be apart of:

Please enjoy the right up of Pathways in the SF Examiner! You can
view the article at

http://tinyurl.com/y55njwa

Cheers from SF-home of Springtime,
Jo-Ann Maggiora Donivan
http://www.donivanandmaggiora.com


#4

Hi Jay,

I don't think you can cast with copper or I would have done it. I
had pretty good luck casting 50% copper and 50% silver, but I think
I overheated the last batch and it was porous. Copper at high temps
does not flow well. I think you are risking anything you attempt to
cast with it. It will be interesting to see if anyone else has a
solution. 

It can be done, but it requires a furnace, which is a different
setup to a hand torch and a dished crucible.

I prefer alloying bronze though it’s a lower melt point due to the
addition of the tin i.e.; copper melts at 1083 C (1981 F), but
adding tin cuttings drops that temperature considerably. A lot of
bronze casters make the mistake of melting the copper first "then"
adding the tin. This is a logical assumption, however alloying bronze
this way will see a lot of your tin vaporising. Tin first, then
copper. Load the crucible with your tin, then cover with granulated
copper. The copper forms a crust, which acts like a lid, and stops
any tin vapor. The lot melts into a nice alloy that is far from pink
:wink:

I digress. Melting copper is not really an issue, it does require a
fair amount of flux to keep it flowing nicely though. I should do a
micro melt at some stage.

Regards Charles


#5

Hi Jo-Ann,

I can give you some tips also.

  1. Use granulated copper, it’s sold that way from metal recyclers,
    and there are a lot of benefits, apart from the obvious that you
    don’t have to spend time cutting up copper.

  2. I just throw the entire charge into the crucible, but I use a
    furnace, and I have a flux used for smelting aluminium… I was
    given 320 kg so I gave 6 canisters to a friend, 2 canisters is 80 kg,
    and I haven’t even dented the first one yet!

  3. See 2) and borax is fine, although it’s very aggressive.

  4. Absolutely, the addition of tin lowers the melt point of the
    copper.

  5. I use gravity, haven’t tried my casting machine, or that sling
    caster that gets everyone running :wink:

  6. I use delft clay and casting sand, haven’t tried it with
    investment plaster.

  7. Good policy

Hey I’m an old dog, but I’m learning new tricks too.

A lot of my friends cast aluminium, they reside on a Yahoo! list

Regards Charles


#6

I was under the impression that heating copper to the melting point -
to fuse or cast - gave forth dangerous gasses?

Maryellen


#7
A lot of bronze casters make the mistake of melting the copper
first "then" adding the tin. This is a logical assumption, however
alloying bronze this way will see a lot of your tin vaporising. 

It’s a logical assumption only if your brain’s on backwards! :wink: If
pure copper (with a drastically higher melting point than tin) is so
hard to melt, and tin (with its drastically lower melting point than
copper) readily alloys with it, then it is logical to me to melt the
tin first and add the copper - which will then melt at a lower
temperature than if it was melted pure - unless of course it’s not as
simple as that. You’d clearly lose some tin if it was done the other
way around. But I guess we don’t all think the same way. There are
plenty of obvious things to some people, which are not obvious to me.

Helen
UK


#8
I was under the impression that heating copper to the melting point
- to fuse or cast - gave forth dangerous gasses? 

Nope, totally incorrect.

James Binnion
James Binnion Metal Arts


#9
I was under the impression that heating copper to the melting
point - to fuse or cast - gave forth dangerous gasses? 

Copper isn’t so bad, it’s what might be with it that might cause you
grief.

Grease, lead, zinc. All nasty stuff.

Copper will make you feel sick, but it’s relatively harmless.

Ventilation is the solution to any gas problem.

Regards Charles


#10
Ventilation is the solution to any gas problem. 

While proper ventilation is a requirement for metal working of any
kind it is highly unlikely while casting you will be heating copper
to the point of vaporization which is over 4500F ( 2500 C) so unless
you are arc welding it you will not be breathing copper fumes. Grease
will should not be a problem as you should never be melting dirty
metal the grease itself is not really an issue but the dirt and
solids in grease will likely remain and contaminate your melt. Zinc
certainly and lead likely are going to be present in brass and many
bronze alloys but not in commercial copper.

James Binnion
James Binnion Metal Arts