Jeff Jeff on wed 6 oct 10
I'm about to run out of cone 06 cones for my electric kiln. I have 05 and
04 cones in the studio as well but I'm not sure about using them for a
bisque.
It occurs to me that I have almost never fired a bisque firing to anything
but a cone 06 temp. (In 30 years of making pots.) It leads me to ask, does
anyone bisque fire to another temp, and if so, do you do so because 06 was
problematic for you?
Even though my slip cast pots are thinner than my wheel thrown pots, in
general, I haven't run into any real glaze application issues maintaining t=
he
06 temp. I've read that other temps have their benefits but I haven't
really experimented enough to know. Has anyone?
Thanks
Jeff Longtin
Minneapolis
Victoria E. Hamilton on wed 6 oct 10
Jeff,
As far as I can tell, bisque firing to 05 (and more so with 04) just leaves
your pots a little less absorbent, and a smidge (technical term) more
durable for handling. Not sure about your slipcast pots, but your thrown
pots should be fine. Testing of course, but all I'd do would be apply the
glaze a little differently - e.g., if dipping, hold the pot in the glaze fo=
r
a count of 4 or 5 instead of a count of 3.
Buona fortuna.
Vicki Hamilton
Seattle
-----Original Message-----
From: Clayart [mailto:Clayart@LSV.CERAMICS.ORG] On Behalf Of Jeff Jeff
Sent: Wednesday, October 06, 2010 7:05 AM
To: Clayart@LSV.CERAMICS.ORG
Subject: bisque temp (06 or otherwise?)
I'm about to run out of cone 06 cones for my electric kiln. I have 05 and
04 cones in the studio as well but I'm not sure about using them for a
bisque.
It occurs to me that I have almost never fired a bisque firing to anything
but a cone 06 temp. (In 30 years of making pots.) It leads me to ask, does
anyone bisque fire to another temp, and if so, do you do so because 06 was
problematic for you?
Even though my slip cast pots are thinner than my wheel thrown pots, in
general, I haven't run into any real glaze application issues maintaining
the
06 temp. I've read that other temps have their benefits but I haven't
really experimented enough to know. Has anyone?
Thanks
Jeff Longtin
Minneapolis
Pottery by John on wed 6 oct 10
Jeff,
I bisque at 08 or 06 for raku work and at 04 for everything else, even low
fire. When I bisqued at 06 for everything, I had bubble and pits with some
work, which is much less at 04.
John Lowes
Sandy Springs, Georgia
http://wynhillpottery.weebly.com/
Lee Love on wed 6 oct 10
If you under bisque, you can always sponge to adjust. If you over
bisque, you might need to thicken your glazes.
--
=3DA0Lee, a Mashiko potter in Minneapolis
http://mingeisota.blogspot.com/
=3D93Observe the wonders as they occur around you. Don't claim them. Feel
the artistry moving through and be silent.=3D94 --Rumi
Marcia Selsor on wed 6 oct 10
For earthenware Majolica maybe bisque as high as ^02
For terra sigs no higher than ^09
For sensitive porcelain maybe ^04.
all depends as always
Marcia
Marcia Selsor
http://www.marciaselsor.com
fran johnson on wed 6 oct 10
I bisque at c. 05, for both my stoneware and porcelain. It works well for b=
=3D
oth clays.=3DA0 At a lower temp the clay was too fragile and had more break=
ag=3D
e just handling it while glazing.
=3DA0
Fran
--- On Wed, 10/6/10, Jeff Jeff wrote:
From: Jeff Jeff
Subject: bisque temp (06 or otherwise?)
To: Clayart@LSV.CERAMICS.ORG
Date: Wednesday, October 6, 2010, 9:04 AM
I'm about to run out of cone 06 cones for my electric kiln. I have 05 and
04 cones in the studio as well but I'm not sure about using them for a
bisque.
It occurs to me that I have almost never fired a bisque firing to anything
but a cone 06 temp. (In 30 years of making pots.) It leads me to ask, does
anyone bisque fire to another temp, and if so, do you do so because 06 was
problematic for you?
Even though my slip cast pots are thinner than my wheel thrown pots, in
general, I haven't run into any real glaze application issues maintaining t=
=3D
he
06=3DA0 temp. I've read that other temps have their benefits but I haven't
really=3DA0 experimented enough to know. Has anyone?
Thanks
Jeff Longtin
Minneapolis
DJ Brewer on thu 7 oct 10
At the college studio where I take classes our professor always
bisques to 08. Says it makes for a more porous bisque that absorbs glaze
better. I'm a neophyte on the subject. I thought everyone bisqued to 08.
DJ
On 10/7/2010 4:41 PM, Snail Scott wrote:
> with a brush anyhow, it makes little real
> difference to me. If I had a product line which relied on
> consistent absorption during glaze dipping, it would be
> far more critical. If I were using an outgassing-vulnerable
> glaze (like a ^06 cadmium red), that would matter, too,
> and I'd want to bisque consistently perhaps two cones
> above the glaze temp, just to be safe.
Snail Scott on thu 7 oct 10
On Oct 6, 2010, at 9:04 AM, Jeff Jeff wrote:
> It occurs to me that I have almost never fired a bisque firing to
> anything
> but a cone 06 temp. (In 30 years of making pots.) It leads me to
> ask, does
> anyone bisque fire to another temp, and if so, do you do so because
> 06 was
> problematic for you?
I've gone higher (as high as ^03), to make harder, more
durable bisque for transport or for reduced absorption,
and I've gone lower (as low at ^012) to save energy or
for a faster firing cycle or higher absorption, or for a softer,
easier to grind bisque. I also change cones when I run
out of one or another.
Since I do not do a production line of ware, and apply
my surfaces with a brush anyhow, it makes little real
difference to me. If I had a product line which relied on
consistent absorption during glaze dipping, it would be
far more critical. If I were using an outgassing-vulnerable
glaze (like a ^06 cadmium red), that would matter, too,
and I'd want to bisque consistently perhaps two cones
above the glaze temp, just to be safe.
I also frequently skip bisque firing altogether. Bisque is
something I do as needed, not out of habit. 'Needs' that
induce me to do so include: 1. using gas-sensitive glazes,
2. doing multi-part work that can be best trued up when it's
strong enough to assemble but soft enough to grind easily,
3. when I'm doing a series and want to surface everything
at once for consistency but fear to have greenware around
the studio for long, and 4. when some 'fiddly bits' might get
damaged during surface applications to greenware.
Some people report serious glaze flaws from very low
bisque temps, but I am not among them.
-Snail
Lee Love on thu 7 oct 10
On Thu, Oct 7, 2010 at 4:41 PM, Snail Scott wro=
=3D
te:
> Some people report serious glaze flaws from very low
> bisque temps, but I am not among them.
Sponging is important for low bisque.
I've also turned several people on to single fire earthenware. It
is good to at least experiment outside the box. Don't be afraid.
--
=3DA0Lee, a Mashiko potter in Minneapolis
http://mingeisota.blogspot.com/
=3D93Observe the wonders as they occur around you. Don't claim them. Feel
the artistry moving through and be silent.=3D94 --Rumi
Snail Scott on fri 8 oct 10
On Oct 7, 2010, at 11:12 PM, DJ Brewer wrote:
> At the college studio where I take classes our professor always
> bisques to 08. Says it makes for a more porous bisque that absorbs
> glaze better. I'm a neophyte on the subject. I thought everyone
> bisqued to 08...
At the college studio where I teach, I have lately
been bisque firing to ^08. I used to bisque to ^04
routinely when I taught elsewhere, so as to leave
the door open for the use of earthenware and ^06
glazes by students. I don't do that at my present
program, however, as our facilities do not allow
for separate low-temperature glaze firings. Thus,
the drop in bisque temps. I see no merit to firing
higher in our current situation, except that less
absorbent bisque might allow for smoother brushed
design work. Still, dampening the bisque will do
pretty well to achieve that same end. A shorter
bisque cycle also makes my schedule slightly more
flexible, in terms of when I can return to campus to
fire another kilnload of work. Lower temps =3D faster
firing and faster cooling, taking an hour or two off
the cycle. Not much, but it's handy, saves energy,
and none of our shop glazes seem negatively
affected.
So why not ^010 or ^012? No real reason, except that
in a cramped classroom situation, damage can happen,
and stronger work lives longer. It's an incremental
change, though. ^06 would be good, but leads to
confusion among beginning students since we glaze
fire to ^6, so I avoid ^06 in the classroom simply to avoid
careless errors. ^04 is good, and stronger yet, but less
absorbent and requires a slightly longer firing cycle. If
we did earthenware, ^03 or even ^02 might be better,
depending on the optimum maturation of the clay.
There are very few clear-cut lines in this matter; mainly
a balancing of relative benefits versus detriments.
-Snail
Brad Sondahl on sat 9 oct 10
I[m aware of two reasons for bisqueing--to harden the pots so they
don't fall apart when glazing, and to burn out organics and sulfur
which can produce pinholes and blisters in the glaze fire. Overfiring
the bisque can result in glaze water not being absorbed into the clay,
making for poor thickness of glaze and slow drying time. I fire to
cone 06, which I've found to be a happy medium. Clays vary on their
sulfur and organic content, and people mostly fire the bisque as they
learned it, unless they have problems. A friend of mine just fired to
visible red heat, which worked for hardening the pots, but he was
having a lot of glaze issues, so I suggested a higher bisque which did
benefit him.
Brad Sondahl
sondahl.com
David Woof on sun 10 oct 10
Hi Jeff=3D2C =3D20
you ask a good question. The answer includes but is not limited to whether=
=3D
06 is problematic in and of itself=3D3B but in the reasons 06 demands oth=
er=3D
supporting techniques and solutions to the problems 06 presents while fixi=
=3D
ng one "problem" that may or may not even exist. =3D20
Potters and clay artists are really not of interest to the clay industry as=
=3D
a whole=3D2C so as clay use in industry has gone ever higher tech=3D2C man=
y in=3D
dustrial demands are for cleaner materials and so our reason for firing hig=
=3D
her is not as valid with more use of the cleaner clays we now have access t=
=3D
o. And our formulated moist clay suppliers are becoming ever more centraliz=
=3D
ed and conscious of quality control. Anyone ready for synthetic clay? We=
=3D
have arrived!!!
I usually bisque to 010 on utilitarian ware unless a particular body does h=
=3D
ave a gassing problem at the lower cones=3D2C or if a higher cone bisque an=
d =3D
consequently a tighter body is what I desire for some other application. A=
=3D
nd why would I deliberately use a problem body unless it offered some uniqu=
=3D
e quality not found anywhere else and I wanted it sooo bad? =3D20
Like everything we do=3D2C it is easy to get into a habit and then develop =
te=3D
chnique to support it and stop questioning rather than take the time out to=
=3D
ask more questions and try or learn a new and possibly a more efficient ap=
=3D
proach. Glad you too are thinking/asking. =3D20
I think some folks unquestioningly fire to 06 and then again unquestioningl=
=3D
y use epsom salts as a Flocculent. This thickened (less water ratio) prope=
=3D
rty or characteristic compensates for the less absorbent quality of the cla=
=3D
y at this higher fired temp and the thicker glaze consistency builds an ade=
=3D
quate thickness on these pots of lower absorbency. =3D20
=3D20
Forgotten in all this may be that the original reason to fire to cone 06 w=
=3D
as that some dirty bodies needed to fire that high to burn away the organic=
=3D
combustibles that could later cause gassing craters and pin holes. There a=
=3D
re other cause as well but higher bisque fixed some problems so this info g=
=3D
ot published=3D2C as so it should=3D2C and folks started to do 06 as a stan=
dard=3D
and largely forgot why while at the same time advocating flocculation as t=
=3D
he supporting solution to the problem caused by the higher bisque. A closed=
=3D
loop until someone stops and asks why and could there be a better way.
=3D20
However for my general use=3D2C I fire to cone 010 and deflocculate my glaz=
es=3D
with Glass Magic=3D2C and add bentonite and CMC as mechanical suspenders a=
s =3D
well. Deflocculated and suspended in this combination allows the glaze to =
=3D
flow smoothly from loaded brushes=3D2C sprays well=3D2C and to dip and pour=
wit=3D
h ease. And with the added benefit to stay virtually bottom cakeing free e=
=3D
ven over extended periods of storage time for most glazes. Not all defloccu=
=3D
lants have equal effects. Glass Magic=3D2C not at all formulated for potter=
s=3D
=3D2C has hit on something of special quality in this regard =3D20
I do keep a bottle of magnesium sulfate on hand for that rare day when I ch=
=3D
ose to floc something
.
I observe that accurate information on flocculation/deflocculation=3D2C bis=
qu=3D
e firing temps=3D2C etc=3D2C is scattered and one must hunt it=3D2C collect=
it an=3D
d question whether some of the info out there is simply an unwitting repeti=
=3D
tion of parts that have been lost or misinterpreted in the several generati=
=3D
ons of transmission. Some of it may have to die with the diehards as change=
=3D
comes hard even when not to is harder still. We all have preferences=3D=
2C=3D
access to certain materials and we each must find our own truth.
=3D20
It excites me when I see me stop and ask the question that leads to change=
=3D
=3D2C and it does good for me when someone else does too. Go for it!!!
=3D20
David Woof
=3D20
=3D20
14a. Re: bisque temp (06 or otherwise?)
On Oct 6=3D2C 2010=3D2C at 9:04 AM=3D2C Jeff Jeff wrote:
> It occurs to me that I have almost never fired a bisque firing to
> anything
> but a cone 06 temp. (In 30 years of making pots.) It leads me to
> ask=3D2C does
> anyone bisque fire to another temp=3D2C and if so=3D2C do you do so becau=
se
> 06 was
> problematic for you?
=3D20
=3D
Karen Gringhuis on thu 14 oct 10
Both Sondahl & Woof discuss the role of bisque firing temperature in =3D
burning
out organic materials to avoid pinholes and blisters. But no one (unless=
=3D
I
missed it) has mentioned the role of TIME in bisque firing.=3D20=3D20
Years ago, after experiencing blisters**, etc., I turned to the Orton Fdt=
=3D
n.
for help. After breaking and analyzing one problem example, they (Dale
Fronk) advised a temperature rise from red heat up to final temp. of NO
FASTER than 100 degrees F per minute. This solved the problem and I've
bisqued this way ever since.=3D20
My electric kiln has no computer controller but I use a digital pyrometer=
=3D
(don't leave home without it!).=3D20=3D20
This SLOWER temp. rise schedule also helped friends solve these same
problems. And a fast rise recently contributed to a near-disaster for a
friend who should have known better.=3D20
Electric firing incl. bisque is not as simple as some people seem to thin=
=3D
k.
But that's another story.=3D20
** Blisters under only one of the two glazes on the SAME pot - anyone who=
=3D
wants the whole story, write me back.
Karen Gringhuis
Ron Roy on thu 14 oct 10
And!
The amount of oxygen present is crucial. Sometimes the amount of
organics burning out is enough that all the available oxygen is used
up - and/or the insides of lidded forms or bowls upside down will
result in oxygen being used up. It's not hard to see the difference in
the colour of reduced clay - even with white bodies.
So time, temperature and a source of new oxygen are all factors.
If you need to go faster - open a couple of spy holes - or better
still - use a vent system to make sure there is enough fresh air.
RR
Quoting Karen Gringhuis :
> Both Sondahl & Woof discuss the role of bisque firing temperature in burn=
ing
> out organic materials to avoid pinholes and blisters. But no one (unless=
I
> missed it) has mentioned the role of TIME in bisque firing.
>
> Years ago, after experiencing blisters**, etc., I turned to the Orton Fdt=
n.
> for help. After breaking and analyzing one problem example, they (Dale
> Fronk) advised a temperature rise from red heat up to final temp. of NO
> FASTER than 100 degrees F per minute. This solved the problem and I've
> bisqued this way ever since.
>
> My electric kiln has no computer controller but I use a digital pyrometer
> (don't leave home without it!).
>
> This SLOWER temp. rise schedule also helped friends solve these same
> problems. And a fast rise recently contributed to a near-disaster for a
> friend who should have known better.
>
> Electric firing incl. bisque is not as simple as some people seem to thin=
k.
> But that's another story.
>
> ** Blisters under only one of the two glazes on the SAME pot - anyone who
> wants the whole story, write me back.
>
> Karen Gringhuis
>
Lee Love on fri 15 oct 10
Also, I bisque high organic clay bodies to 012 and lower with no problems.
--
=3DA0Lee, a Mashiko potter in Minneapolis
http://mingeisota.blogspot.com/
=3D93Observe the wonders as they occur around you. Don't claim them. Feel
the artistry moving through and be silent.=3D94 --Rumi
Lee Love on fri 15 oct 10
On Thu, Oct 14, 2010 at 2:37 PM, Karen Gringhuis wrot=
=3D
e:
> Both Sondahl & Woof discuss the role of bisque firing temperature in burn=
=3D
ing
> out organic materials to avoid pinholes and blisters. =3DA0But no one (un=
le=3D
ss I
> missed it) has mentioned the role of TIME in bisque firing.
Pinholes that appear immediately after glazing can be eliminated by
sponging low fired bisque before it is glazed.
I single fire with no problems related to organics.
--
=3DA0Lee, a Mashiko potter in Minneapolis
http://mingeisota.blogspot.com/
=3D93Observe the wonders as they occur around you. Don't claim them. Feel
the artistry moving through and be silent.=3D94 --Rumi
Lee Love on fri 15 oct 10
On Fri, Oct 15, 2010 at 11:23 AM, wrote:
> How about pinholes AFTER firing. (electric) Do you think LONGER bisque, a=
=3D
s
> opposed to fast fire, might be the answer?
>
> I never heard of a debate about LENGTH of bisque before Steve(?) brought =
=3D
it
> up?
Maybe. But the pinhole problem might be solved firing a
little higher or holding at the end of the firing too
One way to see if organics are the culprit is to fire a
non-organic body along with one containing organics.
--
=3DA0Lee, a Mashiko potter in Minneapolis
http://mingeisota.blogspot.com/
=3D93Observe the wonders as they occur around you. Don't claim them. Feel
the artistry moving through and be silent.=3D94 --Rumi
Lee Love on mon 18 oct 10
On Thu, Oct 7, 2010 at 10:13 PM, Lee Love wrote:
> On Thu, Oct 7, 2010 at 4:41 PM, Snail Scott w=
=3D
rote:
> =3DA0I've also turned several people on to single fire earthenware. =3DA0=
It
> is good to at least experiment outside the box. =3DA0 Don't be afraid.
Kip O'Krongly is one of the persons I turned on to single fire
earthenware. See some of her work here:
http://www.kipokrongly.com/Minnesota.html
--=3D20
--
=3DA0Lee, a Mashiko potter in Minneapolis
http://mingeisota.blogspot.com/
=3D93Observe the wonders as they occur around you. Don't claim them. Feel
the artistry moving through and be silent.=3D94 --Rumi
| |
|
