CP Dunbar on thu 17 apr 97
Quote from Val Cushing - (page 43)
Stoneware should bebisque fired between C/010 & up to C/06.
Many fire to C/08 as ideal
Never go Lower than C/ 010. At C//04 stoneware will start to
harden & become more difficult to glaze. But porcelain should
be bisques to C/04 - never lower than C/06.
-Stoneware comments anyone ?
how high do you bisque ?
problems ?
answers ?
anecdotes ?
bad mother-in-laws ?
thanx. cp
--
"And she shall have music wherever my Lady goes."
cpdunbar@concentric.net
Dana Henson on sat 6 jun 98
I've never used majolica before and am about to make up a recipe that is to be
fired to cone 04/03. Can anyone please tell me what temperature to bisque to?
Thanks in advance...
Dana Henson
G_Henson@venus.twu.edu (Denton, TX)
mel jacobson on fri 30 jul 99
i have been all over the place on this one.
i have settled on cone 08 as my general purpose
bisque temp.
others fire 06, but i find it very hard, and it does
not suck up enough glaze for me.
i like to layer glazes, or mabe three thin dips for the
average pot.
this topic has gone around and around, but each potter
seems to find a range that works for them.
i was doing as low as cone 011, but, man you have to be
careful....a great deal of glaze pulls in real fast.
mel/mn just fire the bisque slow.
http://www.pclink.com/melpots
from minnetonka, minnesota, u.s.a.
Ron Roy on mon 2 aug 99
I have always (40 years) bisqued at cone 04 - everything. There are a few
good reasons for this - ware is stronger when bisqued higher and is the
main recommendation when potters are experiencing bisque dunting - it is
always advisable with porcelain which is particularly susceptible to
dunting on the way down at the quartz inversion (573C) - porcelain always
has a lot of free quartz in it.
As to having trouble getting glaze to stay on ware that's fired to 04 - I
have never had that problem - the glaze does have to be thicker in the
bucket but you will have more control because the ware is not so absorbent
- the main advantage to having your glazes thicker in the bucket - it stays
suspended longer.
RR
Ron Roy
93 Pegasus Trail
Scarborough, Ontario
Canada M1G 3N8
Tel: 416-439-2621
Fax: 416-438-7849
Web page: http://digitalfire.com/education/people/ronroy.htm
Maria Elaine Lanza on wed 4 aug 99
Thanks Ron for responding to my bisque temp concern... have a couple of
questions about your reply though that I hope you will answer as well :
!. Would you still recommend ^04 bisque temp for ^6 porcelain?
2. When you say that the glaze needs to be thicker... at what reading on the
hydrometer would you recommend the glaze density should be... I usually aim
for 3.5... thicker?
Thanks again, Marie Elaine
> ----------------------------Original message----------------------------
> I have always (40 years) bisqued at cone 04 - everything. There are a few
> good reasons for this - ware is stronger when bisqued higher and is the
> main recommendation when potters are experiencing bisque dunting - it is
> always advisable with porcelain which is particularly susceptible to
> dunting on the way down at the quartz inversion (573C) - porcelain always
> has a lot of free quartz in it.
>
> As to having trouble getting glaze to stay on ware that's fired to 04 - I
> have never had that problem - the glaze does have to be thicker in the
> bucket but you will have more control because the ware is not so absorbent
> - the main advantage to having your glazes thicker in the bucket - it
stays
> suspended longer.
>
> RR
>
>
> Ron Roy
> 93 Pegasus Trail
> Scarborough, Ontario
> Canada M1G 3N8
> Tel: 416-439-2621
> Fax: 416-438-7849
>
> Web page: http://digitalfire.com/education/people/ronroy.htm
>
Ron Roy on sat 7 aug 99
Hi Elaine,
Answer to #1: Yes, absolutely.
Answer #2: I don't use a hydrometer for testing the slop - and I don't
think - in the long run it is accurate enough when the slop starts changing
reology. Better to find another way. If you want to establish criteria for
slop thickness - using any criteria - here is what you should do. Using
some bisque fired at the new bisque temperature - mix your glaze up thicker
than you would normally use it (take some water off) - dip a tile into it
and use what ever method you choose to gauge the thickness at that point.
Add more water - dip another piece of bisque - gauge thickness, repeat till
you are satisfied you have less thickness than you think will work. Fire
all the test pieces to find out what thickness is right.
How much water to add at a time - depends on how much glaze there is of
course - for every household bucket try a cup more water each time - even
if you don't get it right on you will know it is between two points.
What is reology? This has to do with what happens to suspensions when they
change due to chemical influences. A flocculated slop will need more water
to appear the same thickness, a deflocculated slop will need less water to
appear the same thickness. Sodium is a well know deflocculator, Epsom salts
is a well know flocculator.
Perhaps someone else could explain this in a better way.
RR
>----------------------------Original message----------------------------
>Thanks Ron for responding to my bisque temp concern... have a couple of
>questions about your reply though that I hope you will answer as well :
>
>1. Would you still recommend ^04 bisque temp for ^6 porcelain?
>
>2. When you say that the glaze needs to be thicker... at what reading on the
>hydrometer would you recommend the glaze density should be... I usually aim
>for 3.5... thicker?
>
>Thanks again, Marie Elaine
Ron Roy
93 Pegasus Trail
Scarborough, Ontario
Canada M1G 3N8
Tel: 416-439-2621
Fax: 416-438-7849
Web page: http://digitalfire.com/education/people/ronroy.htm
Joyce Lee on mon 9 aug 99
RR or anybody who can help ...
I'm using a kiln-sitter. Since my beginning forays into pottery I've put
an 06^ into the kiln sitter for bisque firing, thinking that meant I was
firing to ^06. Now you're talking about 04^ being your choice for bisque
firing. Question: when my 06^ bends, does that mean it's actually gone
through the 06 firing and has hit 04? My owner's manual does not address
this. I know it's elementary info that I should know by this time, but
I'm trying to fill the holes in my clayart education .... gaps, chasms
... and David doesn't want me to post directly any more ... sad... and
Dannon and Vince are out of town ... and Tony is busy ... and Geoff has
clay troubles of his own ... and no telling where Mel is ...sigh ... and
I really don't have an open dance card elsewhere ... pitiful...
Thank you.
Joyce
In the Mojave listening to the 4:30 a.m. tree frogs ... so pleased the
frogs seem to be returning to the desert ... ours, of course, are more
"bush" frogs since, at least on our scrub acreage, we have few trees.
Nice sound ... sound of life.
Tom Wirt on mon 9 aug 99
> Hi Elaine,
>
> Answer #2: I don't use a hydrometer for testing the slop - and I don't
> think - in the long run it is accurate enough when the slop starts
changing
> reology.
Elaine,
Picking up on Ron's post re: measuring glaze thickness, once you've found
the proper coating thickness and its related glaze/water mix, the way to
measure Specific Gravity, rather than a hydrometer is by weight.
What you are trying to measure is the amount of glaze material suspended in
water.
We use an 8 oz. plastic jar with a sharp rim. And we use the same jar for
all measurements. We fill the container just until the fluid (water or
glaze) fills under the rim.
Now take your good glaze slop (the one that gave you the correct application
thickness) and weigh it. From then on, you can use that weight to ensure
that you've got the same proportion of water to glaze ingredients every
time.
If you do need to know the specific gravity (say to give someone else the
glaze), You will also need to weigh the same container full to the same
point with just water. Divide your glaze weight by the water weight and
you've got specific gravity.
Once you've got the specific gravity of the correct water/solids mix, if you
mix a new batch and it's too thick or thin for glazing, you can use
flocculants and deflocculants to adjust the apparent thickness for proper
application.
Hydrometers are made for measuring specific gravity of solutions. Glazes
are suspensions. The solid particles in the glaze keep the hydrometer from
accurately indicating the specific gravity, I assume because of the drag
they exert on the glass tube. That's why the weighing method is more
accurate.
Hope this helps
Tom Wirt
Dewitt Gimblet on mon 9 aug 99
In my little Skutt, witness cones show that an 04 bar in the sitter gives
05 through most of the kiln. You will need an 04 or possibly an 03 in the
sitter to get a true 04. Only way to tell is to run a load or two with
witness cones.
deg
At 10:26 AM 8/9/99 -0400, you wrote:
>----------------------------Original message----------------------------
>RR or anybody who can help ...
>
>I'm using a kiln-sitter. Since my beginning forays into pottery I've put
>an 06^ into the kiln sitter for bisque firing, thinking that meant I was
>firing to ^06. Now you're talking about 04^ being your choice for bisque
>firing. Question: when my 06^ bends, does that mean it's actually gone
>through the 06 firing and has hit 04? My owner's manual does not address
>this. I know it's elementary info that I should know by this time, but
>I'm trying to fill the holes in my clayart education .... gaps, chasms
>... and David doesn't want me to post directly any more ... sad... and
>Dannon and Vince are out of town ... and Tony is busy ... and Geoff has
>clay troubles of his own ... and no telling where Mel is ...sigh ... and
>I really don't have an open dance card elsewhere ... pitiful...
>
>Thank you.
>
>Joyce
>In the Mojave listening to the 4:30 a.m. tree frogs ... so pleased the
>frogs seem to be returning to the desert ... ours, of course, are more
>"bush" frogs since, at least on our scrub acreage, we have few trees.
>Nice sound ... sound of life.
>
Joyce Lee on tue 10 aug 99
Wow! Sure thing about Clayart ... all your regulars abandon you for
bigger&better ... and there are new ones to take their place! June, of
course, was my very first guru ... great to hear from her.......and
Bonnie always answers my pleas ... did again, thank you. Bill from
Persimmon Hill hasn't checked in, though. But thanks to Karen, Mike,
Deg, Merrie, and yea! Dannon's back, and many others who will be hearing
from me ....it seems clear that when 06 bends in the sitter, it means
you have reached 06 at that spot in the kiln. If you want 04, you'll
have to put an 04 in the sitter. Thank you.
Joyce
In the Mojave where she'll be glad when everybody's through with their
summer gallivanting, and get back in cyberspace to offer their talents
where they're appreciated.
Stephen Mills on tue 10 aug 99
Dear Joyce,
Worry not dear Lady,
06 bending means heatwork to 06 has been achieved, no more and no less,
which is what you were after.
Steve
Bath
UK
In message , Joyce Lee writes
>----------------------------Original message----------------------------
>RR or anybody who can help ...
>
>I'm using a kiln-sitter. Since my beginning forays into pottery I've put
>an 06^ into the kiln sitter for bisque firing, thinking that meant I was
>firing to ^06. Now you're talking about 04^ being your choice for bisque
>firing. Question: when my 06^ bends, does that mean it's actually gone
>through the 06 firing and has hit 04? My owner's manual does not address
>this. I know it's elementary info that I should know by this time, but
>I'm trying to fill the holes in my clayart education .... gaps, chasms
>... and David doesn't want me to post directly any more ... sad... and
>Dannon and Vince are out of town ... and Tony is busy ... and Geoff has
>clay troubles of his own ... and no telling where Mel is ...sigh ... and
>I really don't have an open dance card elsewhere ... pitiful...
>
>Thank you.
>
>Joyce
>In the Mojave listening to the 4:30 a.m. tree frogs ... so pleased the
>frogs seem to be returning to the desert ... ours, of course, are more
>"bush" frogs since, at least on our scrub acreage, we have few trees.
>Nice sound ... sound of life.
>
--
Steve Mills
Bath
UK
home e-mail: stevemills@mudslinger.demon.co.uk
work e-mail: stevemills@bathpotters.demon.co.uk
own website: http://www.mudslinger.demon.co.uk
BPS website: http://www.bathpotters.demon.co.uk
Ben Shelton on wed 11 aug 99
I'm of the train of thought that any cone in the sitter is about one cone
behind the same cone when placed in a cone pack. This is why the packaging
usually say "witness" cone whatever. You're supposed to see it going down.
Anyone else???
Ben
-----Original Message-----
From: Joyce Lee
To: CLAYART@LSV.UKY.EDU
Date: Tuesday, August 10, 1999 1:48 PM
Subject: bisque temp
>----------------------------Original message----------------------------
>Wow! Sure thing about Clayart ... all your regulars abandon you for
>bigger&better ... and there are new ones to take their place! June, of
>course, was my very first guru ... great to hear from her.......and
>Bonnie always answers my pleas ... did again, thank you. Bill from
>Persimmon Hill hasn't checked in, though. But thanks to Karen, Mike,
>Deg, Merrie, and yea! Dannon's back, and many others who will be hearing
>from me ....it seems clear that when 06 bends in the sitter, it means
>you have reached 06 at that spot in the kiln. If you want 04, you'll
>have to put an 04 in the sitter. Thank you.
>
>Joyce
>In the Mojave where she'll be glad when everybody's through with their
>summer gallivanting, and get back in cyberspace to offer their talents
>where they're appreciated.
>
Ray Aldridge on wed 11 aug 99
At 01:47 PM 8/10/99 EDT, you wrote:
>from me ....it seems clear that when 06 bends in the sitter, it means
>you have reached 06 at that spot in the kiln. If you want 04, you'll
>have to put an 04 in the sitter. Thank you.
>
I'm not sure if this is actually true. In my experience, I have to put an
03 cone in the sitter to get 04 on an adjacent shelf. 9 in the sitter
means 8 in the kiln. I theorize that this is because the weight of the
sitter rod causes the cone to deform before it would if only supporting its
own weight in a near-upright position. If slight variations in angle when
placed in a cone pack can influence the temp at which the cone drops, then
surely the weight of the sitter rod would have a much larger effect.
Ray
David Woodin on wed 11 aug 99
Just because an 06 in the sitter shuts off the kiln doen't mean the kiln
fired to cone 06. The only way to be sure is to use some witness kilns on
vaious shelves in your kiln. On the other hand probably the cone 06 bending
in the sitter indicated the bisque firing was hot enough. Glaze firings
need to be backed up with witness cones to be sure of what cone to use in the
sitter. Other things also affect the sitter calibration such as is the rod
bend? has its size changed? was the sitter calibrated using the jig that
comes with the kiln?
David
Don Prey on thu 12 aug 99
In a message dated 08/11/99 7:33:52 AM, you wrote:
<behind the same cone when placed in a cone pack. This is why the packaging
usually say "witness" cone whatever. You're supposed to see it going down.
Anyone else???
>>
Ben, My experience with a number of kilns over the last 12 years has been
as follows: Depending on the kiln and the adjustment/maintenance of the
sitter, I find that there can be about a 3/4 to 1 and 3/4 cone difference.
The difference is such that the kiln shuts down too early. That is to say,
if I want to bisque to 08 I will put a cone 06 in the sitter (Orton Jr. cone
in the sitter, Orton large cone on the shelf next to the ware). When doing a
cone 5 glaze fire, I will be using a Jr. cone 6 or 7....depending on specific
glazes, type of load and all that. I let the kiln setter terminate a bisque
firing, but always use whitness cones (large) and terminate the firing myself
for a glaze firing (this may entail a reset of the power on the sitter if it
trips before the witness cones tell me I'm finished).
Not only do the Jr. and Large cones react differently to heat work, but they
were designed to be used standing at a specific angle and to bend under there
own weight. The kiln sitter is really a safety device, not a heat work
monitor, per se. The other option available is to use Orton Pyrometric Bars
in the sitter. They deform in a manner that closely matches the large
standing cones. In any case there are enough variables operating to warrant
some calibration of the kiln/sitter system. The only valid measurement is a
large witness cone on the shelf next to the ware, if we want to compare
results and speak a consistent language (I'm pretty sure you already knew
that).
Don Prey in Oregon
Jim Brooks on sat 14 aug 99
Don , i did agree with you about the one cone higher in the kiln setter
thing.. until..i placed cone packs in the kiln to see... and was i
surprised!!! I got a perfect cone 06 bend with a cone 06 in the setter..
Tony Hansen on tue 17 aug 99
> 06 bending means heatwork to 06 has been achieved, no more and no less,
> which is what you were after.
I'm not so sure. We use Buller's rings also in every firing.
Two firings might bend a cone 6 to 3 oclock. On one the cone 5 might be totally
flat and melting and the cone 7 not started, on the other the cone 5 may only be
bent a little more than the 6 and the 7 might be at 2 oclock. The latter firing
will give a much smaller Buller's ring indicating more heat and temperature.
--
T o n y H a n s e n thansen@digitalfire.com
Don't fight the dragon alone http://digitalfire.com
Calculation/Database Software for Ceramic Industry
--
Stephen Mills on wed 18 aug 99
That's interesting. Are you firing a fuel burning Kiln or Electric? I
know from experience that exterior temperatures can affect Kiln
performance especially with my little wood Kiln that lives outside. Not
so sure about indoor Electric ones though.
I think that relative to the question asked the answer was right.
Steve
Bath
UK
In message , Tony Hansen writes
>----------------------------Original message----------------------------
>> 06 bending means heatwork to 06 has been achieved, no more and no less,
>> which is what you were after.
>
>I'm not so sure. We use Buller's rings also in every firing.
>Two firings might bend a cone 6 to 3 oclock. On one the cone 5 might be totally
>flat and melting and the cone 7 not started, on the other the cone 5 may only b
>bent a little more than the 6 and the 7 might be at 2 oclock. The latter firing
>will give a much smaller Buller's ring indicating more heat and temperature.
>
>--
>T o n y H a n s e n thansen@digitalfire.com
>Don't fight the dragon alone http://digitalfire.com
>Calculation/Database Software for Ceramic Industry
>--
>
--
Steve Mills
Bath
UK
home e-mail: stevemills@mudslinger.demon.co.uk
work e-mail: stevemills@bathpotters.demon.co.uk
own website: http://www.mudslinger.demon.co.uk
BPS website: http://www.bathpotters.demon.co.uk
Marie Gibbons on tue 5 jun 01
I have another question on this topic
Is there much of a difference in the strength of a piece when you fire at say
cone 04 to cone 06? I bisque to 04 and then use cold finishes, or room temp
glazes . I am considering going to the lower cone, 06 or 05 and wondering if
I will be compromising the strenght of the clay. I typically use a lowfire
raku clay, handbuilding.
opinions?
marie
www.oooladies.com
mel jacobson on mon 7 mar 05
there are at least 3,590 posts in the archives about bisque
temps. and, there are at least 50 versions of those 3,590.
people have strong opinions.
i like ron roy's stance.
long bisque.
really long bisque.
i do twenty hours.
i prefer cone 08 as i layer all of my glazes.
i need that extra absorption. most use 06.
i have done 08 long bisque cycle for 40 years.
i am not going to change now.
and i have 5 boxes left of cone 08.
ybtmv
your bisque temp may vary. but, make them long.
mel jacobson/minnetonka/minnesota/usa
http://www.pclink.com/melpots
http://www.rid-a-tick.com
Rimas VisGirda on thu 25 feb 10
Years ago we used to bisque at 010 to save energy (at the univ) glaze and f=
ire to 10/11. This worked fine until we started making a claybody with abou=
t 1/3 Goldart... started getting bloats in the high fire. When broken open =
there was a yellowish residue in the bloat. Found that the sulfur in Goldar=
t, if not completely driven out (during the bisque) gassified? in the wall =
and pushed it out when the clay got soft at the high temp. I talked tothe G=
oldart people and they suggested firing bisque to 05 with a hols at the end=
. We did that, without the hold, and that solved the problem. -Rimas
Rimas VisGirda on thu 25 feb 10
Before the sulfur problem, we never had problems with burning out organics =
in 010 (or lower) bisques. Back in the NoCal woodfire days we bisqued to ju=
st past red heat, when i started teaching and having control of the process=
at schools we bisqued to 010 to save energy (until the sulfur problem in a=
previous post). The NoCal clay had lots of organics, but not a problem as =
far as bisquing was concerned, my assumption is that the organics burn out =
in the glaze firing before the glaze starts to liquify, even sintered clay =
is porous enough to allow gasses to pass. The only problem with low bisque =
is the added fragility of the pieces, which is not a problem at all -if you=
can handle your greenware you should be able to handle your (low) bisquewa=
re... The lower bisque does affect the absorption properties of the clay, b=
ut that's not a problem either if you bisque to the (approximately) same te=
mp AND keep your glazes to the (approximately) same consistency. AND
it's not really necessary to use a hydrometer -we used to to stick our han=
d into the (mixed) glaze and it was right if the hairs rose to the surface;=
if they don't rise, add water. If they rise but you can see the color of y=
our skin, they are too thin -let settle and pour off some water. The other =
factor with this system is the time in the glaze; if we wanted a normal coa=
t it was a count of 2 if we wanted a thicker coat it was a count of 3-5, de=
pending on how thick you wanted. Not very scientific but works for me. -Rim=
as
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