Jenna Logan on sat 11 jul 98
I started using a new midrange brownstone clay , I bisque fired to ^ 06. The
bisqued pots have a white powder (or what looks like a white powder) covering
them . Can anyone tell me what this is & what causes it ? Thanks, Jenna
Earl Brunner on sun 12 jul 98
Probably soluable salts from your water supply or the supply used to mix your
clay. Clays that bisque red or other darker colors sometimes show this in the
bisque, it's usually not hamful and will normally disappear in the glaze fire.
Fay & Ralph Loewenthal on mon 13 jul 98
Jenna that white powder sounds like scumming / salt to
me. If it was a bought clay I would scream blue murder at
the supplier. If it was dug up clay then the only solution I
have heard of is to add barium carbonate to it. Beware this
barium carbonate is not nice stuff, really poisonous. Hope
this helps Ralph in PE SA.
beardiherd on wed 22 dec 99
Thank you all for your help with my bisque question. I am really happy that
I waited and ask the list for help. I knew I had to be right . You don't
hear from me often, but I appreciate your generous willingness to share your
knowledge. My degree and training is in the Nuclear Medicine field, which
Ihate and fortunately do not have to work at very often. I am trying hard
to make my little pottery studio work. But I know I don't know much and I
appreciate having you all here. Thank you Sherry Morrow Besides that, I
didn't want to ruin all those cups!
Linda & Malcolm on mon 9 oct 00
Hi, I'm new to the group although I have been using it as a source of =
information over the past few months. I have a question regarding =
bisquing. I am currently using a c-6 clay (oxidation) which contains =
manganese and have had problems with blistering/pinholing. Laguna clay =
recommended that I bisque to c-04 (I have been bisquing to c-08) and =
that should resolve the problem. Now my question: can I also bisque =
c-10 clay (going into a reduction kiln) to c-04 or is it best to bisque =
that clay to c-08. I'm fairly new to firing, hope all this makes sense. =
=20
=20
Jim V Brooks on mon 9 oct 00
I bisque cone 10 clay to cone 04 often. It will give you a slightly harder
bisque but it wont hurt the clay/pottery. Glaze and fire to cone 6 as
usual.... Jim in Dallas
Cindy Strnad on mon 9 oct 00
Hi, Linda.
I bisque all my clay to ^06, unless I'm pit firing, and then it's less, to
allow for more porosity. If your glaze applies easily to your ^04 bisque,
then ^04 is okay. The glaze should dry within a few minutes. If it doesn't,
you're bisque firing too hot. There was another post (maybe today) that
talked about curing pinholes by firing bisque v-e-r-y slowly. If you don't
like the properties of the ^06 bisque, you might want to try the slower
firing.
Cindy Strnad
Earthen Vessels Pottery
RR 1, Box 51
Custer, SD 57730
USA
earthenv@gwtc.net
http://www.earthenvesselssd.com
vince pitelka on tue 10 oct 00
> i fire to cone 08 bisque...always.
> glaze just sucks up the right way.
> no soaking.
> makes no sense at all.
> fire slow, finish, turn off kiln.
I agree with Mel here. In thirty years I have never soaked a bisque-firing.
I always bisque slowly to cone 08 - usually seven or eight hours.
- Vince
Vince Pitelka
Home - vpitelka@dekalb.net
615/597-5376
Work - wpitelka@tntech.edu
615/597-6801 ext. 111, fax 615/597-6803
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
http://www.craftcenter.tntech.edu/
mel jacobson on tue 10 oct 00
this is an old topic.
i just listen to ron roy. (hero)
fire slow, then slower.
15 hours.
or more.
same cost....20 amps at 10 hours
or 50 amps at 4 hours.
and the pots are better.
i fire to cone 08 bisque...always.
glaze just sucks up the right way.
06 for me is just too hot.
others feel different.
but, they are my pots and i like them best at 08.
no soaking.
makes no sense at all.
fire
slow,
finish,
turn off kiln.
glaze,
make
treasures.
(we hope)
mel
(kurt says i have first pick at the answers...well, that is
what the owner gets...first pick. wholesale)
FROM MINNETONKA, MINNESOTA, USA
http://www.pclink.com/melpots (website)
Steve Mills on wed 11 oct 00
I couldn't agree more, You can never bisc too slowly.
Steve
Bath
UK
In message , mel jacobson writes
> this is an old topic.
>
>i just listen to ron roy. (hero)
>
>fire slow, then slower.
>15 hours.
>
>or more.
>
>same cost....20 amps at 10 hours
>or 50 amps at 4 hours.
>
>and the pots are better.
>
>i fire to cone 08 bisque...always.
>glaze just sucks up the right way.
>
>06 for me is just too hot.
>
>others feel different.
>but, they are my pots and i like them best at 08.
>
>no soaking.
>makes no sense at all.
>fire
>slow,
>finish,
>turn off kiln.
>glaze,
>make
>treasures.
>(we hope)
>mel
>(kurt says i have first pick at the answers...well, that is
>what the owner gets...first pick. wholesale)
>
>
>FROM MINNETONKA, MINNESOTA, USA
>http://www.pclink.com/melpots (website)
>
--
Steve Mills
Bath
UK
Gayle Bair on thu 12 oct 00
Forgive me if this is a stupid question but
is it possible that the ^ one bisques could be a cause
crazing?
Gayle Bair
Gaylebair@bainbridge.net
Snip>
> i fire to cone 08 bisque...always.
> glaze just sucks up the right way.
> no soaking.
> makes no sense at all.
> fire slow, finish, turn off kiln.
I agree with Mel here. In thirty years I have never soaked a bisque-firing.
I always bisque slowly to cone 08 - usually seven or eight hours.
- Vince
vince pitelka on fri 13 oct 00
> Everything remains OK as long as all the pieces in the
> load are small to average size, but once you start trying
> to fire bowls over about 16" in diameter, the cracking begins.
> I think these cracks happen during cooling, when the
> edges of a bowl cool faster than the center. The crack
> happens because the clay has not been fired hard
> enough to resist the force.
> I don't know if this is really what is happening, but Ron
> Roy suggested this when I was discussing it with him,
> and it makes sense to me.
> Increasing the firing back up to cone 06 greatly reduces
> the incidence of these cracks.
David -
I guess it must depend on the claybody. As you know, strength of bone-dry
and bisque-ware depends so much on the distribution of platelate sizes - the
broader the distrubution of sizes, the more contact points, and the stronger
the sintered framework at the bisque-fired stage.
I like the way glazes go onto wares bisqued to cone 08, and that is what I
have always been accustom to. We always bisque-fire to cone 08 at the Craft
Center, and I can't say we have any particular problems with cracking in
large plates and bowls. In the ten years I did production in California I
used several Westwood (now Laguna) claybodies - Rod's Bod, and Danish White
with sand. Large mixing bowls, serving bowls, and platters were a mainstay
for me, and I never had problems with rim cracking.
If I fire a stack of large plates or large shallow bowls with no air-space
between them, I do have problems with cracking, no matter what claybody I
use. I'm sure this is because of the reason you mention above - the rim
heats up before the center. To eliminate this problem, I keep a good supply
of little softbrick shims around - I cut thin slices off scrap softbricks,
and break them up into 1/2" pieces. I place one bowl or platter on the kiln
shelf, and then place three shims around the bottom, then place another
piece, then another three shims in the same location as the previous ones,
then another piece, up to four or five plates or bowls. I never have
problems with cracking when I do this. It is easy to place the shims, and I
use them again and again. This gives enough air space to allow the plate or
bowl to heat up evenly.
Best wishes -
- Vince
Vince Pitelka
Home - vpitelka@dekalb.net
615/597-5376
Work - wpitelka@tntech.edu
615/597-6801 ext. 111, fax 615/597-6803
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166
http://www.craftcenter.tntech.edu/
David Hendley on fri 13 oct 00
I hate to disagree with 2 old pros like Mel & Vince
(not really, I like it), but I think cone 08 is not a hot
enough temperature for bisque firing.
It is not good for my claybody anyway. I have learned
this the hard way, as I gradually, through the years,
lowered my firing temperature from 06 to 08 to save
time and $.
Everything remains OK as long as all the pieces in the
load are small to average size, but once you start trying
to fire bowls over about 16" in diameter, the cracking begins.
I think these cracks happen during cooling, when the
edges of a bowl cool faster than the center. The crack
happens because the clay has not been fired hard
enough to resist the force.
I don't know if this is really what is happening, but Ron
Roy suggested this when I was discussing it with him,
and it makes sense to me.
Increasing the firing back up to cone 06 greatly reduces
the incidence of these cracks.
--
David Hendley
Maydelle, Texas
hendley@tyler.net
http://www.farmpots.com/
| > i fire to cone 08 bisque...always.
| > glaze just sucks up the right way.
| > no soaking.
| > makes no sense at all.
| > fire slow, finish, turn off kiln.
|
| I agree with Mel here. In thirty years I have never soaked a
bisque-firing.
| I always bisque slowly to cone 08 - usually seven or eight hours.
| - Vince
|
Charles on sat 14 oct 00
Wow, I almost hate to say this...but we at The Creative Oasis bisque to
012...no problems on large or small pieces....no bubbling, pitting or other
nastiness...maybe we are just lucky.
-Charles
Visit my webpage...
http://www.thecreativeoasis.com/Hughes/hughes.html
----- Original Message -----
From: David Hendley
To:
Sent: Friday, October 13, 2000 2:14 PM
Subject: Re: bisque
> I hate to disagree with 2 old pros like Mel & Vince
> (not really, I like it), but I think cone 08 is not a hot
> enough temperature for bisque firing.
> It is not good for my claybody anyway. I have learned
> this the hard way, as I gradually, through the years,
> lowered my firing temperature from 06 to 08 to save
> time and $.
>
> Everything remains OK as long as all the pieces in the
> load are small to average size, but once you start trying
> to fire bowls over about 16" in diameter, the cracking begins.
> I think these cracks happen during cooling, when the
> edges of a bowl cool faster than the center. The crack
> happens because the clay has not been fired hard
> enough to resist the force.
> I don't know if this is really what is happening, but Ron
> Roy suggested this when I was discussing it with him,
> and it makes sense to me.
> Increasing the firing back up to cone 06 greatly reduces
> the incidence of these cracks.
>
> --
> David Hendley
> Maydelle, Texas
> hendley@tyler.net
> http://www.farmpots.com/
>
>
>
> Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
Dave Murphy on sat 14 oct 00
Hey David:
I agree with you. I fire alot of beginner work as well as my own production
work. I have not had a mishap, a pinhole or any other problem associated
with bisquing when i upped my temp to 05 (1910 F) I usually take about 12
hours to get there. Very slow to the 212 degrees and then hold for 15
minutes.
ps. I like disagreeing with them too!
Barbara Murphy
Waterloo County Pottery
Waterloo, Ontario
Canada
----- Original Message -----
From: "David Hendley"
To:
Sent: Friday, October 13, 2000 2:14 PM
Subject: Re: bisque
> I hate to disagree with 2 old pros like Mel & Vince
> (not really, I like it), but I think cone 08 is not a hot
> enough temperature for bisque firing.
> It is not good for my claybody anyway. I have learned
> this the hard way, as I gradually, through the years,
> lowered my firing temperature from 06 to 08 to save
> time and $.
>
> Everything remains OK as long as all the pieces in the
> load are small to average size, but once you start trying
> to fire bowls over about 16" in diameter, the cracking begins.
> I think these cracks happen during cooling, when the
> edges of a bowl cool faster than the center. The crack
> happens because the clay has not been fired hard
> enough to resist the force.
> I don't know if this is really what is happening, but Ron
> Roy suggested this when I was discussing it with him,
> and it makes sense to me.
> Increasing the firing back up to cone 06 greatly reduces
> the incidence of these cracks.
>
> --
> David Hendley
> Maydelle, Texas
> hendley@tyler.net
> http://www.farmpots.com/
>
>
>
>
> | > i fire to cone 08 bisque...always.
> | > glaze just sucks up the right way.
> | > no soaking.
> | > makes no sense at all.
> | > fire slow, finish, turn off kiln.
>
> |
> | I agree with Mel here. In thirty years I have never soaked a
> bisque-firing.
> | I always bisque slowly to cone 08 - usually seven or eight hours.
> | - Vince
> |
>
>
____________________________________________________________________________
__
> 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.
>
Ron Roy on wed 18 oct 00
OK so I'm way behind - I know.
I have always bisqued at cone 04 - there are some advantages to this.
If you are using a clay that has a lot of free quartz in it - the pots are
stronger and will resist quartz dunting during bisque cooling. I use
porcelain - those kinds of bodies have 25% quartz. It does not make a
difference if you only do smaller ware but larger platters, plates and
bowls can use the extra hardness.
A higher bisque means your glazes have to be thicker - an advantage in that
thicker glazes settle more slowly between stirs. This is particularly
important with certain glazes - those with less than 5% clay and/or
defocking materials like Neph Sy.
It's just a matter of understanding the science and deciding what to do
based on reality.
RR
Ron Roy
93 Pegasus Trail
Scarborough
Ontario, Canada
M1G 3N8
Evenings 416-439-2621
Fax 416-438-7849
Shanley & Geoff Marchese on wed 20 aug 03
Clear DayHi- my name is Shanley Marchese- and I have a question for you- =
I work with my childrens pre school (A LOT!)
and for our anual Fall Festival we have each class do some sort of class =
project involving the children that we then auction off to earn funds =
for our school. Generally these are some sort of Bisque project that =
involves things such as thumb print art, or hand prints . . .something =
of each child. =20
The person who we had do our glazing and fireing has gone out of =
business so I am looking for someone new! I wondered if you know =
someone cheap (or willing to be cheap for a school fundraiser!) who we =
can contact to do our items. The school is located on the NorthWest end =
of town- corner of 290 and Hwy 6 (FM 1960) but we are willing to drive a =
bit if needed. The people we used last year actually we out in Baytown- =
which was a bit far- but we can do it if necessary. =20
We generally have 20 -30 large projects- items such as canisters, =
platters, serving trays, pedastal bowls, or large mixing bowls. =20
Thanks for your help!
Shanley Marchese
gmarchese@houston.rr.com
9403 Meadow Point Court
Houston, TX 77095
281-855-1087
281-788-8115
Bill Edwards on thu 23 oct 03
^06 will work but try using ^04 for your bisque and a
longer firing time if you can. If your using a manual
kiln and 04 cones then fire slower by turning the
knobs up and holding at longer intervals, mainly in
the mid range on the way up for bisque. (For well
dried raw wares) For a computer controlled firing use
the slow fire method to ^04. Just remember, the hotter
you bisque fire your work the less porous it becomes
and less likely to absorb the water from the glaze
mix.
^04 is a little hotter than 06 which will help drive
off impurities and also provide a little less
porosity. Clean your bisqued wares well to remove all
dust. Preferably a good dip in water and allow to
completely dry but if your going to re-dip prior to
complete drying make sure your glaze is a proper
consistency.
This will work for most any pottery (04 bisque)and
includes raku. Its just a standard bisque that I use
and has worked for me for years at ^6 and ^10 as well
as raku. Others will use a different set of rules and
I am late getting in on this thread so you may already
have your answer?
Bill Edwards
Tamara Williams
Subject: dumb question inside
ok.. so if a clay says cone 6.. how do I bisque fire
it? is it
^06 =
bisque and THEN ^6 Glaze? or ^6 for both?? I'm in
such a fog I
can't =
remember right now and my grandma got me all confused
=====
http://www.tallapoosariverpottery.com/
Bill Edwards
PO Box 267
Lafayette, AL, 36862
__________________________________
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The New Yahoo! Shopping - with improved product search
http://shopping.yahoo.com
Donna Kat on tue 19 jun 07
It would help to know where and in what way the plates are cracking. Are
they getting air both on the top and the bottom of the floor? Have you
tried waxing the lip? If the plate is bottom side down on a solid base the
stress of shrinkage could be the problem or it may not be compressed
enough. You might try going back over the bottom with a rubber or wood
rib.
On Thu, 14 Jun 2007 07:41:25 -0700, cindy pegg wrote:
>Not sure if this will go thru. I am not receiving messages and cannot get
into archives.
> Having a problem with bisque cracking. Large platters 1/2 thickness are
cracking, but not the plates that are smaller. New automatic kiln was
bisqued at med. will switch to low. Propping lid until 1000 degrees. Is
this correct?
>
>
>---------------------------------
>Need Mail bonding?
>Go to the Yahoo! Mail Q&A for great tips from Yahoo! Answers users.
>
>__________________________________________________________________________
____
>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.
Lee Love on mon 16 jun 08
On Mon, Jun 16, 2008 at 1:37 PM, Bill Merrill wrote:
> bisqued to cone 010-012 for my stoneware.
In my woodfired bisque, the kiln is at 012 at the top (the hottest
part.) The rest is cooler.
I also single fire, which is something all folks should consider
with skyrocketing energy prices. Single firing is evidence that low
bisque should not be a problem with the right glazes and clay body.
--
Lee Love in Minneapolis
http://mashikopots.blogspot.com/
http://claycraft.blogspot.com/
"We are such stuff as dreams are made on, and our little life is
rounded with a sleep." --PROSPERO Tempest Shakespeare
Bill Merrill on mon 16 jun 08
Bisquing at cone 04 is good for porcelain, because porcelain doesn't
start to vitrify at that temperature and the body can be handled easier.
I would not advise=20
Bisquing to Cone 04 for stoneware. The body can start to become denser
and a glaze could have a hard time adhering to the piece. I have always
bisqued to cone 010-012 for my stoneware. There has never been bloating
etc. with the body I make, and the body has 15% Newman red in it. I do
not bisque fire fast. I fire slow enough to let the carbonaceous
materials in the clay burn off. When glazing, I use a hydrometer made
for heavy liquids to keep my glazes at a particular consistency.
Different glazes have different amounts of water added. Glazes with
more clay for example will use more water than a glaze with less clay.
To keep the glaze from going on too thick or thin, I count while the
piece in submerged in the glaze. I get consistent results applying
glaze this way. If spraying, I count revolutions of a pot on a
turntable and use a needle to occasionally check the thickness of the
glaze on the pot. You can count even when pouring glaze. Glazing is
when most people are frenzied to get pots glazed and get the kiln loaded
and firing. I would suggest that you make 2 or 3 carloads of pots then
glaze and when a firing is going on, glaze the next load. Get a rhythm
going. Mix clay, throw pots, dry them. Bisque, glaze fire....start the
cycle over. Dave Shaner fired a 90 cubic foot kiln every 10 days or so.
Keep making pots the best ones are still in you.
=20
Bill
Ron Roy on tue 24 jun 08
Hi Bill,
I've been bisquing at 04 for everything for 60 years - never had the clay
glassify - never had an adhesion problem - even for cone 04, 6, and 8
clays.
Not only does it allow for thicker glazes in the bucket - it also helps
prevent bisque dunting and helps to burn out impurities in iron bearing
clay to help prevent overfiring.
It is especially important at lower temperatures - when glazes have little
raw clay in them and need the added thickness to stay suspended.
It has been the solution to many potters problems - I can't understand why
you would try to scare people away from trying something that solves so
many problems?
RR
>Bisquing at cone 04 is good for porcelain, because porcelain doesn't
>start to vitrify at that temperature and the body can be handled easier.
>I would not advise
>
>Bisquing to Cone 04 for stoneware. The body can start to become denser
>and a glaze could have a hard time adhering to the piece. I have always
>bisqued to cone 010-012 for my stoneware. There has never been bloating
>etc. with the body I make, and the body has 15% Newman red in it. I do
>not bisque fire fast. I fire slow enough to let the carbonaceous
>materials in the clay burn off. When glazing, I use a hydrometer made
>for heavy liquids to keep my glazes at a particular consistency.
>Different glazes have different amounts of water added. Glazes with
>more clay for example will use more water than a glaze with less clay.
>To keep the glaze from going on too thick or thin, I count while the
>piece in submerged in the glaze. I get consistent results applying
>glaze this way. If spraying, I count revolutions of a pot on a
>turntable and use a needle to occasionally check the thickness of the
>glaze on the pot. You can count even when pouring glaze. Glazing is
>when most people are frenzied to get pots glazed and get the kiln loaded
>and firing. I would suggest that you make 2 or 3 carloads of pots then
>glaze and when a firing is going on, glaze the next load. Get a rhythm
>going. Mix clay, throw pots, dry them. Bisque, glaze fire....start the
>cycle over. Dave Shaner fired a 90 cubic foot kiln every 10 days or so.
>Keep making pots the best ones are still in you.
>
>
>
>Bill
Ron Roy
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
| |
|
