Kate Johnson on thu 2 sep 04
...or maybe it ISN'T crazy and it just sounds that way to me.
Someone was asking me about making an enclosed form, for a flask--not unlike
Chris's whistle concept. We've been kicking around how that might be
possible, given that I don't have a wheel, so I'm looking at built forms.
(I'm figuring on joining two sides made over a dome-shape myself...)
One of the fellows thought I could make a form with ice, which would then
melt out (and make mud? Slip?), and another just asked if I couldn't make a
wax form and them melt THAT out. Um. At firing temps? This sounds like a
real "hey, Bubba, watch THIS" kind of trick. Darwin Awards idea. I know
lost wax works with jewelry making and sculpture, but...don't know about in
a kiln.
He thought if I just heated it enough to melt the wax out before firing, it
would work. I'm concerned about all that wax soaking into the raw clay.
What say you? Is this crazy Rube Goldberg stuff, or an old established
technique?!
Regards,
Kate Johnson
Graphics/Fine Arts
http://www.cathyjohnson.info/
http://www.epsi.net/graphic/
Earl Brunner on thu 2 sep 04
I don't think wax would work for the reason you thought of yourself. Where
is the melting wax going to go. It will BURN at some point, in a gas kiln
that might not be a disaster, but the sudden heat from the flames might. In
an electric kiln it is sure to cause MAJOR problems, not the least of which
would be the smoke. We had some children made forms that were made around
bunched up paper that caused enough smoke (even with exhaust fans)at our art
center awhile back, that someone called the fire department.
Another problem is that as your pieces dry, they will shrink, and then crack
because the wax won't shrink with them. Your best bet is probably to make
two half forms and then connect them.
Earl Brunner
Las Vegas, NV
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Kate Johnson
Sent: Thursday, September 02, 2004 3:39 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: crazy question about lost wax...
...or maybe it ISN'T crazy and it just sounds that way to me.
Someone was asking me about making an enclosed form, for a flask--not unlike
Chris's whistle concept. We've been kicking around how that might be
possible, given that I don't have a wheel, so I'm looking at built forms.
(I'm figuring on joining two sides made over a dome-shape myself...)
One of the fellows thought I could make a form with ice, which would then
melt out (and make mud? Slip?), and another just asked if I couldn't make a
wax form and them melt THAT out. Um. At firing temps? This sounds like a
real "hey, Bubba, watch THIS" kind of trick. Darwin Awards idea. I know
lost wax works with jewelry making and sculpture, but...don't know about in
a kiln.
He thought if I just heated it enough to melt the wax out before firing, it
would work. I'm concerned about all that wax soaking into the raw clay.
What say you? Is this crazy Rube Goldberg stuff, or an old established
technique?!
Warren Heintz on thu 2 sep 04
The process of lost wax casting is an old one and
before the use of investment,plaster like
materials,clay was used to make moulds. Th ewax was
packed with clay,and in firing the clay both burnrd
out the wax and fired the clay creating the flask. A
pouring sprew ,made of wax created the opening for the
wax to exit/burn or melt out and later allowed for the
metal to be poured in. It should work,only problem
that I can immediately see is distorting the wax while
packing on the clay the clay. And also what temperture
metals you might use. I've casted pewter(650degrees?)
but using plaster. Make very sure plasteris completely
dried out. Hope this helps.
--- Kate Johnson wrote:
> ...or maybe it ISN'T crazy and it just sounds that
> way to me.
>
> Someone was asking me about making an enclosed form,
> for a flask--not unlike
> Chris's whistle concept. We've been kicking around
> how that might be
> possible, given that I don't have a wheel, so I'm
> looking at built forms.
> (I'm figuring on joining two sides made over a
> dome-shape myself...)
>
> One of the fellows thought I could make a form with
> ice, which would then
> melt out (and make mud? Slip?), and another just
> asked if I couldn't make a
> wax form and them melt THAT out. Um. At firing
> temps? This sounds like a
> real "hey, Bubba, watch THIS" kind of trick. Darwin
> Awards idea. I know
> lost wax works with jewelry making and sculpture,
> but...don't know about in
> a kiln.
>
> He thought if I just heated it enough to melt the
> wax out before firing, it
> would work. I'm concerned about all that wax
> soaking into the raw clay.
> What say you? Is this crazy Rube Goldberg stuff, or
> an old established
> technique?!
>
> Regards,
> Kate Johnson
> Graphics/Fine Arts
> http://www.cathyjohnson.info/
> http://www.epsi.net/graphic/
>
>
______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change
> your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be
> reached at melpots@pclink.com.
>
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Kate Johnson on thu 2 sep 04
Hi Earl!
>I don't think wax would work for the reason you thought of yourself. Where
> is the melting wax going to go. It will BURN at some point, in a gas kiln
> that might not be a disaster, but the sudden heat from the flames might.
> In
> an electric kiln it is sure to cause MAJOR problems, not the least of
> which
> would be the smoke.
And it is an electric kiln that I have access to. Sounded like a VERY bad
idea to me, but I wanted to check, thank you!
We had some children made forms that were made around
> bunched up paper that caused enough smoke (even with exhaust fans)at our
> art
> center awhile back, that someone called the fire department.
That DID happen once at the high school...I think it was a raku firing,
though.
>
> Another problem is that as your pieces dry, they will shrink, and then
> crack
> because the wax won't shrink with them. Your best bet is probably to make
> two half forms and then connect them.
That was the plan, before all the wonderful, wild, wacky ideas started
pouring in. Thanks, I'll stick to plan one!
Best--
Kate
Kim Lindaberry on thu 2 sep 04
It could be dangerous to use just any clay body to try this method out.
The thermal shock of hot metal hitting the wrong clay body (or
improperly prepared clay body) could cause the mold to crack (or
explode) and molten metal to shoot out. There is a modern day casting
method referred to as "ceramic shell". That method utilizes a
combination of specialized ceramic materials for the mold. The mold
cracking is also always a potential problem even using those
specialized ceramic shell materials. One problem is that as wax heats
up it expands and it may crack a ceramic material mold before it
becomes hard. Often there are specialized steam heating units that are
used first to melt the wax out before the mold is placed in a kiln for
firing.
Definitely research the ceramic shell method to see if it would be
practical for you to pursue.
On Sep 2, 2004, at 8:08 PM, Warren Heintz wrote:
> The process of lost wax casting is an old one and
> before the use of investment,plaster like
> materials,clay was used to make moulds. Th ewax was
> packed with clay,and in firing the clay both burnrd
> out the wax and fired the clay creating the flask. A
> pouring sprew ,made of wax created the opening for the
> wax to exit/burn or melt out and later allowed for the
> metal to be poured in. It should work,only problem
> that I can immediately see is distorting the wax while
> packing on the clay the clay. And also what temperture
> metals you might use. I've casted pewter(650degrees?)
> but using plaster. Make very sure plasteris completely
> dried out. Hope this helps.
Kate Johnson on fri 3 sep 04
Hi Ivor...
> Oh boy, has this one taken of into outer space.
> Original inquiry was for some sort of inner support or armature around
> which a clay piece could be built.
> The mind boggles.
Yep. Meanwhile I've made four flasks today, the first two using rice as
a support, which pours out easily, leaving only a few grains behind so far,
and they'll burn out. The second two I just used air as the support, making
a closed vessel, letting it get about leather hard and then tapping it into
shape (Spanking? Paddling? What DO you call that?) The air itself offered
plenty of resistance in the clay balloon. When it was really leather hard,
I cut a hole for the spout, built a cylinder, and affixed it with slip.
The initial shape on all but one I simply did in two pieces, in a papier
mache box used as a mold. Then used slip and "stitched" them together,
reinforced the seam with a coil of soft clay.
The final one is a very small flask--it was just a small slab of clay folded
over, edges sealed, and blown full of air. After it got leather hard
thereabouts, I paddled it into a flash shape.
I'm tired. But thanks for the help, all...even that that wasn't germane
to my problem was interesting.
Regards,
Kate Johnson
Graphics/Fine Arts
http://www.cathyjohnson.info/
http://www.epsi.net/graphic/
> Ivor Lewis
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
>
Logan Oplinger on fri 3 sep 04
On Thu, 2 Sep 2004 17:39:11 -0500, Kate Johnson wrote:
>...or maybe it ISN'T crazy and it just sounds that way to me.
>
>Someone was asking me about making an enclosed form, for a flask--not
unlike
>Chris's whistle concept. We've been kicking around how that might be
>possible, given that I don't have a wheel, so I'm looking at built forms.
>(I'm figuring on joining two sides made over a dome-shape myself...)
>
>One of the fellows thought I could make a form with ice, which would then
>melt out (and make mud? Slip?), and another just asked if I couldn't make
a
>wax form and them melt THAT out. Um. At firing temps? This sounds like a
>real "hey, Bubba, watch THIS" kind of trick. Darwin Awards idea. I know
>lost wax works with jewelry making and sculpture, but...don't know about in
>a kiln.
>
>He thought if I just heated it enough to melt the wax out before firing, it
>would work. I'm concerned about all that wax soaking into the raw clay.
>What say you? Is this crazy Rube Goldberg stuff, or an old established
>technique?!
>
>Regards,
>Kate Johnson
>Graphics/Fine Arts
>http://www.cathyjohnson.info/
>http://www.epsi.net/graphic/
Hello Kate,
You do not say how complex the outer surface of your clay shapes will be.
If they are not too complex there are two possibilities that come to mind.
1. Slip cast the shapes, or
2. Press mold the shapes.
Either method requires that a negative plaster mold be cast around a
positive model of the desired shape. The shapes should be simple enough so
that the plaster mold requires only two or three sections. The model can
be made of any substantial material like wax, clay, plaster, wood, etc.
Except for wax, the model surface will need to be coated with a thin layer
of petroleum jelly so the plaster will not stick. The plaster mold is cast
in two or more sections.
Slip casting is more involved in that it will require special casting
clays, plus a few chemical additives.
Press molding may be simpler for a limited number of shapes. Once the
plastic clay has been pressed by hand into the plaster mold, the clay is
allowed to dry to leather hard and shrink away from the mold. The sections
of each shape can then be joined together.
For both methods it is important that there are no undercuts in the surface
of the shape, and that there are no odd appendages that would cause the
clay to catch on the mold and crack as it shrinks.
There are many ceramics books that cover the subject of slipcasting, and
the methods of slip cast mold making can be applied to press molds as well.
I hope this helps.
Logan Oplinger
Another Tropical Island
Ivor and Olive Lewis on fri 3 sep 04
Dear Kate Johnson,
The big problem with using a "Wax Core" over which to model clay is
that the competition between shrinkage of your clay and the lack of
resilience of the "Core" material will cause your clay to crack and
perhaps fall from its support.
So you have to think in terms of something which will compress under
the force imposed by your shrinking, drying, clay. I'm sure you will
think of something to do the job.
Best regards,
Ivor Lewis.
Redhill,
S. Australia.
.
Kate Johnson on fri 3 sep 04
Hi Ivor...
> Dear Kate Johnson,
> The big problem with using a "Wax Core" over which to model clay is
> that the competition between shrinkage of your clay and the lack of
> resilience of the "Core" material will cause your clay to crack and
> perhaps fall from its support.
Ah, didn't think of that problem, though I DID think to remove cork stoppers
I used to round the inkwell holes before the little things were dry--good
thing, too. Same/same...
> So you have to think in terms of something which will compress under
> the force imposed by your shrinking, drying, clay. I'm sure you will
> think of something to do the job.
Actually I'll probaby just do two halves and join them when almost leather
hard, thereabouts. If I need to have the shape supported while reaching
that stand-alone stage, I think I'll fill the form with rice or
beans--people who make formed leather vessels do that, I believe. Anyway,
the beans could be poured out before the form begins to shrink in drying...I
think. Sound good?
Best--
Kate
Ivor and Olive Lewis on fri 3 sep 04
Oh boy, has this one taken of into outer space.
Original inquiry was for some sort of inner support or armature around
which a clay piece could be built.
The mind boggles.
Ivor Lewis
Ivor and Olive Lewis on sat 4 sep 04
Dear Kate Johnson,
I suppose you have already consulted F. Carlton Ball and Janice Lovoos
seminal book on "Making pottery without a wheel" ISBN 0671609270.
They just about covers all the option.
Have fun with your work.
Best regards,
Ivor Lewis.
Redhill,
S. Australia
Kate Johnson on sat 4 sep 04
> Dear Kate Johnson,
> I suppose you have already consulted F. Carlton Ball and Janice Lovoos
> seminal book on "Making pottery without a wheel" ISBN 0671609270.
> They just about covers all the option.
No, but it's now on my list! I have several books that cover built forms
among other options, but not one wholly devoted to the subject. Thank
you...
> Have fun with your work.
ALWAYS. I'm about ready to get back to the big foliate face/greenman wall
sculpture after all this practical stuff...hope the plastic has kept him
likewise...
Best--
Kat
Kate Johnson on tue 14 sep 04
Hi Ivor--
> Dear Kate Johnson,
> I suppose you have already consulted F. Carlton Ball and Janice Lovoos
> seminal book on "Making pottery without a wheel" ISBN 0671609270.
> They just about covers all the option.
> Have fun with your work.
I have just received the book...actually, darn it, TWO copies, because
Amazon said the first one had been sold, so try again. Now I have
two...grmph. But it is marvelous and very helpful, thank you! The styles
are a bit dated to my eye, but the basic information is pure gold.
Best--
Kat
Ivor and Olive Lewis on wed 15 sep 04
Dear Kate Johnson,
Pleasing to hear of your success.
Styles are cyclic, what goes around comes around, again, and again,
and again.
But principles are eternal.
As some say, adopt, adapt then individualise.
Best regards,
Ivor.
Kate Johnson on wed 15 sep 04
> Dear Kate Johnson,
> Pleasing to hear of your success.
> Styles are cyclic, what goes around comes around, again, and again,
> and again.
> But principles are eternal.
> As some say, adopt, adapt then individualise.
Thank you, Ivor. I'm in a kind of interesting spot, here...most of the
pottery I am making at the moment is historically inspired redware (a tad
older than the 1965 of the _Making Pottery Without a Wheel_ book, more along
the lines of 200+ year old stuff). I am not trying to reproduce it exactly,
though I would love to be able to get a bit closer to the original. I still
HAVE to put my individual stamp on it...
(Probably why I continue to sculpt, simultaneously...I'm not happy _only_
reproducing an historic style, anyway.)
I met a wonderful potter over the weekend who also sells to the living
history market--Lisa Crews. She has shards and photos of original French
pottery 250+ years old, and uses the beautiful and intricate blue designs on
her own work, both as borders and centerpieces. (She also does Native
American style pit-fired stuff, hand built. WONDERFUL.) I was quite
inspired by her dedication to research--traveling to archaeological digs and
museums, taking measurements and photos...
But...I still have to "adapt, adopt, and individualize," as you say. I
think Lisa does, too...such a balancing act. I respect what went before, I
love it, but...
...gotta go fire my new greenman sculpture...
Thanks again...
Best--
Kate
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