Bob Masta on wed 8 dec 04
Judie:
The problem with trying to melt metals in your kiln
is that they will likely oxidize long before they melt,
if you just put in bare metal chunks. This is true
in electric kilns for certain (from experience!) and
no doubt in fuel kilns unless they are in constant
reduction (no experience there).
I believe that you need to put the metal in a crucible
and cover it with something. It might work in a saggar
with a sealed lid. You may also be able to coat the
metal with something that will keep out the oxygen
until the metal (and the coating) melts, then pour
the molten metal out from under the resulting slag.
Best regards,
> Date: Tue, 7 Dec 2004 06:39:49 -0500
> From: Judie
> Subject: Re: CLAYART Digest - 4 Dec 2004 to 5 Dec 2004
> (#2004-337)
>
> Has anyone ever attempted to manipulate metal in the kiln. I
> would like to know melting points and different variables
> and which metals would work best for this. I'm interested to
> get any feedback from anyone who has worked with this
> technique and medium in the past. Thanks. Judie
>
Bob Masta
potsATdaqartaDOTcom
Tarrant, Derek on wed 8 dec 04
Judie,
Depending on your choice of metal this can be quite easily achieved.
I work in a Zinc company so forgive the bias. But really, the low melting
point of Zinc (795 degrees F) makes this an easy choice as well as a safer
one. The shorter time to melt in a ceramic kiln will reduce oxidation and
once a layer of oxide (dross) forms on the top that tends to inhibit further
reaction. Remove the crucible and scrape the dross to one side before
pouring.
Copper, bronzes and iron by comparison melt at more than twice that
temperature and are considerably more hazardous to handle.
I don't want to preach but be very careful with molten metals. They are
VERY fluid and can explode with devastating effects if poured into a damp
mold or come into contact with water (steam explosion). A hat, full face
shield, arm protectors or heavy sleeves, mineral fiber gloves, jeans and
good boots I would say are a must. A strong crucible with a good flat base
and easily gripped rim plus a properly engineered pair of tongs wouldn't
hurt either.
There are several commercially available Zinc die-casting alloys you could
use depending on your end use requirement. Probably a gravity casting
alloy such as ZA27 for sand casting or ZA12 or ZA8 for sand and permanent
mold casting would do. Alternatively there are slush casting alloys (used
in a very similar way to slip casting but in a non porous mold and done much
more quickly) which are used to make hollow items or non structural things
like decorative casket corners and lamp bases etc. See Eastern Alloys
website - http://www.eazall.com/ for more comprehensive details.
You can use HEAVY Aluminium or steel or cast iron permanent metal molds.
Smoke the inside surface with a sooty candle flame to get metal release.
Hope this helps
Regards,
Derek
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Bob Masta
Sent: Wednesday, December 08, 2004 9:48 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: Melting metal in the kiln
Judie:
The problem with trying to melt metals in your kiln
is that they will likely oxidize long before they melt,
if you just put in bare metal chunks. This is true
in electric kilns for certain (from experience!) and
no doubt in fuel kilns unless they are in constant
reduction (no experience there).
I believe that you need to put the metal in a crucible
and cover it with something. It might work in a saggar
with a sealed lid. You may also be able to coat the
metal with something that will keep out the oxygen
until the metal (and the coating) melts, then pour
the molten metal out from under the resulting slag.
Best regards,
> Date: Tue, 7 Dec 2004 06:39:49 -0500
> From: Judie
> Subject: Re: CLAYART Digest - 4 Dec 2004 to 5 Dec 2004
> (#2004-337)
>
> Has anyone ever attempted to manipulate metal in the kiln. I
> would like to know melting points and different variables
> and which metals would work best for this. I'm interested to
> get any feedback from anyone who has worked with this
> technique and medium in the past. Thanks. Judie
>
Bob Masta
potsATdaqartaDOTcom
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Harry Peery on thu 9 dec 04
I don't want to preach but be very careful with molten metals. They are
> VERY fluid and can explode with devastating effects if poured into a damp
> mold or come into contact with water (steam explosion).
Derek,
As an aside to your mention of the crucible, I took some classes on metal
casting (silver). We would put the silver slugs in a crucible and melt them
with our torches. I once witnessed a woman walk halfway across the room with
melted silver in the crucible shouting "Coming through, hot stuff" whilst
holding her hand under the crucible in case of any drips! (shaking head)
Your cautionary warning is necessary, indeed.
Sue in sunny 80 degree Florida, where the weather refuses to believe it's
almost winter.
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