James Freeman on wed 7 apr 10
Shula...
Most of my sculptural pieces are fired to cone 06 or 04. I usually
bisque them to cone 04, but occasionally I will bisque to cone 6. The
high bisque makes the piece much stronger, and materially alters how
some of my glazes will look, though it does make the piece much harder
to glaze. Sometimes I bisque to cone 04, liner glaze to cone 6, then
glaze the outside with 06 or 04 glazes.
Your piece will be much weaker if you low fire it using your mid or
high fire clay, as it will essentially remain just bisqueware. If
this strength is good enough for your piece, then you are fine. My
own clay is a cone 6-10 body, but my low fired sculptural pieces are
plenty strong. They won't hold water, but not many people drink out
of a sculpture. If bisque strength is insufficient for what you are
doing, and if you do not wish to simply use an earthenware clay, then
I would suggest a cone 6 bisque followed by a low glaze firing, though
glazing will be a LOT more work.
No reason why you can't spray your low fire glazes. All of my pieces
are sprayed.
Never used paper clay, but can't see why it too wouldn't be just fine
at 06-04 for a sculpture.
Have fun.
...James
James Freeman
"All I say is by way of discourse, and nothing by way of advice. I
should not speak so boldly if it were my due to be believed."
-Michel de Montaigne
http://www.jamesfreemanstudio.com
http://www.flickr.com/photos/jamesfreemanstudio/
http://www.jamesfreemanstudio.com/resources
On Wed, Apr 7, 2010 at 10:07 PM, Shula wrote:
> I usually fire to cone 6+ - functional ware and crystalline glazed pieces=
=3D
- in an electric kiln. I've been thinking about making some sculptural for=
=3D
ms and am considering using glazes that fire at cone 04. I have a couple of=
=3D
questions that I'm hoping some Claybuds can give me some help with:
> =3DA0- I usually bisque at cone 04. If I am going to glaze at cone 04, to=
w=3D
hat cone do I bisque the sculpture?
> =3DA0- Is there any reason that I can't / shouldn't spray cone 04 glazes?
> =3DA0- I use Aardvark cone 5 bee mix for most of my functional ware. If I=
u=3D
se this clay for the sculptural forms and only fire to cone 04, will that m=
=3D
ake the sculptures more fragile or otherwise negatively impact the pieces?
> =3DA0- If I use cone 5 paperclay for the sculptural forms and only fire t=
o =3D
cone 04, will that make the sculptures more fragile or otherwise negatively=
=3D
impact the pieces?
>
Shula on wed 7 apr 10
I usually fire to cone 6+ - functional ware and crystalline glazed pieces -=
in an electric kiln. I've been thinking about making some sculptural forms=
and am considering using glazes that fire at cone 04. I have a couple of q=
uestions that I'm hoping some Claybuds can give me some help with:
- I usually bisque at cone 04. If I am going to glaze at cone 04, to what =
cone do I bisque the sculpture?
- Is there any reason that I can't / shouldn't spray cone 04 glazes?
- I use Aardvark cone 5 bee mix for most of my functional ware. If I use t=
his clay for the sculptural forms and only fire to cone 04, will that make =
the sculptures more fragile or otherwise negatively impact the pieces?
- If I use cone 5 paperclay for the sculptural forms and only fire to cone=
04, will that make the sculptures more fragile or otherwise negatively imp=
act the pieces?
Thanks for your help.
Shula
Shula
Desert Hot Springs, California USA
www.claymystique.etsy.com
Stephani Stephenson on thu 8 apr 10
Hi Shula, i'm rambling this evening. i put some of your questions in quot=
=3D
es
, followed by my responses. I must admit, my general take is, in this
situation, there are quite a few variables and no hard and fast rules!
Shula wrote :
..."thinking about making some sculptural forms and am considering using
glazes that fire at cone 04. "=3D20
"If I am going to glaze at cone 04, to what cone do I bisque the sculptur=
=3D
e?"
The clay you select has handling , fired and glaze response characterist=
=3D
ics.
Handling properties are important. if you will be making forms you have m=
=3D
ade
before, and like the handling of your current clay, try working with it f=
=3D
irst.
Yes, it will be underfired at cone 04, it will be more absorbant and not=
=3D
as
strong, but whether it is strong enough for your forms depends on the
specific forms, their size, function and what you want from them. In your=
=3D
climate, added porosity should not make a differentce, unless the sculptu=
=3D
res
need to hold water, and even then you can probably use a penetrating
sealant.(did i hear the ssssssss of ssssacrilege from ssssssomewhere?)
you could choose a clay body with a lower maturation temp, but you migh=
=3D
t
find it difficult to work with in the way it handles and joins for you. =
=3D
So
, if it were me , I would experiment with the clay I am accustomed to,
though, just for fun and learning, I might order samples of other clays=
=3D
,
including raku bodies, just to compare . and i would compare fired color=
=3D
at
04, compare absorption, copare strength, compare glaze response, make bar=
=3D
s
and sample forms and see how easily the bars snap and the forms hold up. =
=3D
I
would also compare greenstrength, and drying and joining characteristics =
=3D
.=3D20
- "I usually bisque at cone 04. If I am going to glaze at cone 04, to wh=
=3D
at
cone do I bisque the sculpture?"
You can bisque the piece at 04 , or you can even bisque the piece to a
higher temperature
, say cone 01 to cone 2 to gain strength and clay color, then glaze fire =
=3D
at
cone 04. this tends to work with open bodies. some fine grained bodies
don't do so well , and may crack in the glaze fire, or the finer grained
bodies may not absorb glaze too well, if they have been bisqued too high,=
=3D
too close to their maturation temp.
but, the gist is, you can experiment to find out what works with your cl=
=3D
ay,
glazes, and firing range.=3D20
Or do both firings to cone 04. that is certainly easier, as you can tha=
=3D
n
combine your glaze and bisque firings.
- "Is there any reason that I can't / shouldn't spray cone 04 glazes?"
there is no reason you shouldn't spray them. use the s=
=3D
ame
safety precautions, and i am assuming you are not spraying lead glazes.
- "I use Aardvark cone 5 bee mix for most of my functional ware. If I us=
=3D
e
this clay for the sculptural forms and only fire to cone 04, will that ma=
=3D
ke
the sculptures more fragile or otherwise negatively impact the pieces?"
since i don't know your forms, i'll gamble and say that it=
=3D
probably won't negatively impact the work. the world is full of lowfire
sculpture of all sizes and shapes, and all of it isn't done with ringing=
=3D
matured , fired clay. but , only your own testing will answer conclusive=
=3D
ly
for you.
- If I use cone 5 paperclay for the sculptural forms and only fire to co=
=3D
ne
04, will that make the sculptures more fragile or otherwise negatively
impact the pieces?
try it out. i would make a fairly simple form, b=
=3D
ut
of a similar size and weight, to find out .
A final note on glazes. you may have to experiment with=
=3D
glazes. they will look different on different bodies. you can apply slip=
=3D
s,
underglazes, etc, if you feel the claybody itself is not giving you the
glaze response you desire. Crazing is much more common with lowfire gla=
=3D
zes
, especially on underfired bodies. whenever you change temps, expect to d=
=3D
o a
little searching for the right clay/glaze/temperature combination. do som=
=3D
e
tests with regard to handling, fired strength, color and glaze response. =
=3D
I
find that some "lowfire sculpture' bodies are difficult to work with,
especially in joining slabs. If you like the way your cone 5 b-mix handle=
=3D
s,
might as well see how it does at the lower temperature. if the work is
decorative in nature.. some of the rigorous requirements (as per
dinnerware), need not be adhered to quite as stringently...
there's a lot that can be done at cone 04
anyway, hope this helps .=3D20
Snail Scott on sun 11 apr 10
On Apr 7, 2010, at 9:07 PM, Shula wrote:
> - I usually bisque at cone 04. If I am going to glaze at cone 04, to
> what cone do I bisque the sculpture?
Some low-fire glazes are sensitive to the outgassing of
underfired bisque, so bisque to at least the cone of the
glaze you will use, or a cone or so more just to be sure.
You may choose to go higher for other reasons, however.
(see below).
> - Is there any reason that I can't / shouldn't spray cone 04 glazes?
No. They are just glazes, after all.
> - I use Aardvark cone 5 bee mix for most of my functional ware. If I
> use this clay for the sculptural forms and only fire to cone 04,
> will that make the sculptures more fragile or otherwise negatively
> impact the pieces?
> - If I use cone 5 paperclay for the sculptural forms and only fire
> to cone 04, will that make the sculptures more fragile or otherwise
> negatively impact the pieces?
They will be more fragile than if made from a proper
low-fire clay body, whether of paperclay or not. There
is also likely to be bad glaze fit with an underfired body,
resulting in crazing. For best results, use a body that is
formulated for your firing temperature. You can also
apply low-fire glazes to a vitrified ('high-bisqued') clay,
though you need to use a few tricks to get good adhesion
since there will be no absorption. You can also stop
short of full vitrification, and pick a somewhat lower firing
temp that will be a good compromise between strength
and absorption while minimizing crazing. Many people
choose ^1 or 2 for this. Testing your particular glaze and
clay combo will be necessary, though.
-Snail
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