Tony Ferguson on sun 31 aug 08
Fred,
They are drying stress cracks. Dry them slowly. Also make sure you are compressing with the rib properly when you are throwing them--especially in those areas. A common mistake is to compress in some areas or not at all with porcelain. What porcelain are you using?
Tony Ferguson
F Parker wrote: I am trying (operative word = "trying") to throw a set of eight large dinnerplates. Out of the eight I threw only three made it into the bisque kiln. I thought the three came through the bisque just fine, then I discovered a hairline crack about 2" long in one just below the rim on the inside.
Most of the failures have happened during drying. Some were radial cracks in the rims. Others were complete separations of the rims from the plate bottoms -- again, during drying. The plates are thrown to approximately 12.5" diameters using 4 pounds of Standard #365 ^6 porcelain.
It seems very, very slow drying under plastic helps. I throw using either a plaster bat or a particle board bat.
I would very much appreciate any advice on how to improve my success ratio.
Thank you,
Fred Parker
Take Care,
Tony Ferguson
...where the sky meets the lake...
http://www.tonyferguson.net
Tony Ferguson on sun 31 aug 08
Ok, I see you use standard. I know nothing about it standard and what I said still applies.
Tony Ferguson
F Parker wrote: I am trying (operative word = "trying") to throw a set of eight large dinnerplates. Out of the eight I threw only three made it into the bisque kiln. I thought the three came through the bisque just fine, then I discovered a hairline crack about 2" long in one just below the rim on the inside.
Most of the failures have happened during drying. Some were radial cracks in the rims. Others were complete separations of the rims from the plate bottoms -- again, during drying. The plates are thrown to approximately 12.5" diameters using 4 pounds of Standard #365 ^6 porcelain.
It seems very, very slow drying under plastic helps. I throw using either a plaster bat or a particle board bat.
I would very much appreciate any advice on how to improve my success ratio.
Thank you,
Fred Parker
Take Care,
Tony Ferguson
...where the sky meets the lake...
http://www.tonyferguson.net
Lynn Goodman Porcelain Pottery on mon 1 sep 08
Hi Fred,
^6 porcelain plates can be persnickety as they dry. Working on
plaster is an excellent idea, as it allows the center to dry at close
to the same rate as the rim. Try covering just the rim as it dries:
take a piece of plastic that will completely cover your plate. Cut
out the middle to leave the center open and the rim covered. I also
put a sheet of newspaper over the center to slow, but not stop
drying. When it seems that the plate is leather hard and the rim can
support weight, I often put a lightweight bat onto the rim to stop
warping and slow drying.
Good luck,
Lynn
On Aug 31, 2008, at 9:47 PM, F Parker wrote:
> Most of the failures have happened during drying. Some were radial
> cracks in the rims. Others were complete separations of the rims
> from the plate bottoms -- again, during drying. The plates are
> thrown to approximately 12.5" diameters using 4 pounds of Standard
> #365 ^6 porcelain.
>
Lynn Goodman
Fine Porcelain Pottery
Cell 347-526-9805
www.lynngoodmanporcelain.com
Curtis Benzle on mon 1 sep 08
Hi Fred: In addition to the well advised compression, you might want to dry
them on newsprint after trimming---it allows them to slide during
shrinkage. Good luck.
Curt
On Sun, Aug 31, 2008 at 8:47 PM, F Parker wrote:
> I am trying (operative word = "trying") to throw a set of eight large
> dinnerplates. Out of the eight I threw only three made it into the bisque
> kiln. I thought the three came through the bisque just fine, then I
> discovered a hairline crack about 2" long in one just below the rim on the
> inside.
> Most of the failures have happened during drying. Some were radial cracks
> in the rims. Others were complete separations of the rims from the plate
> bottoms -- again, during drying. The plates are thrown to approximately
> 12.5" diameters using 4 pounds of Standard #365 ^6 porcelain.
> It seems very, very slow drying under plastic helps. I throw using either
> a plaster bat or a particle board bat.
> I would very much appreciate any advice on how to improve my success ratio.
> Thank you,
> Fred Parker
>
>
>
>
Rikki Gill on mon 1 sep 08
Fred,
There are many different porcelain clay bodies. If possible, try different
bodies to see what works best for you. Not all are hard to throw, not all
crack easily.
Also, I always use plaster bats. And I use my ribs, metal and plastic, to
push out
any air under the bottom of the piece while throwing. When the rim is
drying pretty well, and the piece can be removed from the bat, invert the
piece to dry the bottom a bit before trimming. After trimming, keep it
covered for a day or so, and then gradually let the air dry it. You can
also cover the top with a light weight masonite bat to keep the piece from
warping while waiting for it to dry enough to handle.
Hope this helps.
Rikki
----- Original Message -----
From: "F Parker"
To:
Sent: Sunday, August 31, 2008 6:47 PM
Subject: Question for the porcelain gurus
I am trying (operative word = "trying") to throw a set of eight large
dinnerplates. Out of the eight I threw only three made it into the bisque
kiln. I thought the three came through the bisque just fine, then I
discovered a hairline crack about 2" long in one just below the rim on the
inside.
Most of the failures have happened during drying. Some were radial cracks in
the rims. Others were complete separations of the rims from the plate
bottoms -- again, during drying. The plates are thrown to approximately
12.5" diameters using 4 pounds of Standard #365 ^6 porcelain.
It seems very, very slow drying under plastic helps. I throw using either a
plaster bat or a particle board bat.
I would very much appreciate any advice on how to improve my success ratio.
Thank you,
Fred Parker
Antoinette Badenhorst on mon 1 sep 08
Fred If I understand you correctly, the crack is in a circular shape( following the rim). Additionally to everything what Lynn and Curt and Tony have said, I want to throw in more ideas. My guess is that your normal throwing is fast. Porcelain plates need slower throwing; compressing as you throw. Push the clay out rather than pull( do you see the difference?) and pay attention to every circular movement.
As your experience grows, that kind of detail will come subconsciously, but until then, pay attention to the details.
You do not mention if you trim rims in your plates, but whatever the case; the rim and bottom of the plate should be even in thickness, also (and particularly) right there where the two connect. With other clays one can get away with little flaws; not with porcelain.
Also, if you do trim your plates, allow your clay to be dryer than other clay and use very sharp tools. Trim on a foam bat.
Cover your plates within half an hour after you've made them. I use plastic containers with lids that seal( plastic cake holders are excellent of the purpose.
Let us know how your next batch of plates turn out.
--
Antoinette Badenhorst
www.clayandcanvas.com
www.studiopottery.co.uk
-------------- Original message ----------------------
From: F Parker
> I am trying (operative word = "trying") to throw a set of eight large
> dinnerplates. Out of the eight I threw only three made it into the bisque kiln.
> I thought the three came through the bisque just fine, then I discovered a
> hairline crack about 2" long in one just below the rim on the inside.
> Most of the failures have happened during drying. Some were radial cracks in
> the rims. Others were complete separations of the rims from the plate bottoms
> -- again, during drying. The plates are thrown to approximately 12.5" diameters
> using 4 pounds of Standard #365 ^6 porcelain.
> It seems very, very slow drying under plastic helps. I throw using either a
> plaster bat or a particle board bat.
> I would very much appreciate any advice on how to improve my success ratio.
> Thank you,
> Fred Parker
>
>
>
Craig Martell on mon 1 sep 08
Hello Fred:
It can be very frustrating to lose as many pieces as you've lost so perhaps
some of us can give you some help. That's the plan anyway.
I've made porcelain dinnerware for..........well, a long time and my
success rate is good and I'll tell you how I do the job.
For a twelve inch (this is the thrown diameter) dinner plate I use about
4.5 lbs of clay. I center the clay and then open and flatten the clay to
about 11 inches with the side of my right hand from the end of my little
finger to my wrist. In other words, I use the side of my hand as a big
rib. I don't actually use a rib because I don't want to scrape any clay
away. I rest my left hand on top of the right with a wet sponge for added
water, if needed, and extra pressure. This opens, flattens, and compresses
the clay.
I then throw the rim and flatten it with a rib and then refine the center
of the plate with a rib. I give the rim a good compression by smoothing
and compressing with a wide wet rubber band that I wrap around the rim like
a chamois. I cut the piece off and set all the plates in my damp box and
dry them slowly for about 2-3 days before turning. Turn them upside down as
soon as the rims are dry enough. I turn them and then place them upside
down on wareboards that are covered with paper to compensate for movement
during shrinkage. I bisque fire all my porcelain to cone 03 to give enough
strength to survive the quartz inversion on cooling. I think that cone 04
bisque is fine too.
Don't try to throw plates too thin, especially porcelain. The reality of
making porcelain flatware is that it requires a lot of turning and that's
just the nature of the material. How thin is too thin? You'll have to
determine that for yourself but just keep it in mind and keep working on
the plates.
regards, Craig Martell Hopewell, Oregon
Christine Campbell on mon 1 sep 08
One process I totally misunderstood
when learning about porcelain was
"dry slowly".
What's slow?
A day, a week, longer?
I thought I was going slowly until I
visited a famous porcelain artist
and found out he manipulates the drying
so it takes a month or more. Huge wet
boxes where work was gently turned and
babied until it was dry.
It was a thrill to visit since he was getting
ready for a major show and every surface of
his studio was covered with large snow white
vases and bowls in various stages of the process.
My work routinely dries for weeks now and
the success rate has gone up.
Chris Campbell - in North Carolina
--
Chris Campbell Pottery LLC
9417 Koupela Drive
Raleigh NC 27615-2233
Designs in Colored Porcelain
1-800-652-1008
Fax : 919-676-2062
website: www.ccpottery.com
wholesale : www.wholesalecrafts.com
John Rodgers on mon 1 sep 08
Fred,
My experience with porcelain has taught me that you really have to deal
with a lot of movement in that clay. I throw on plaster bats, and the
absorption of the water from the clay by the bat helps keep shrinkage
fairly uniform. With plates I cover with a large sheet of plastic cut
from a garbage bag. I let it extend way beyond the edges of the plates.
At some point the piece will self release from the bat. After that, the
piece needs to be put on to two or three layers of newspaper for further
drying. The newsprint will move as the clay continues to shrink, thereby
reducing the tendency towards developing stress cracks.
When firing there is still the same problem of movement. Not so much for
bisque firing, but in the finish or glaze firing. With cone 6 porcelain
there needs to be a loose coating of alumina hydrate spread over the
shelf for the porcelain to sit on. The alumina hydrate act almost like
ball bearings and allows the porcelain to slide unrestricted as it shrinks.
When firing porcelain to high fire - with or without a glaze on it - I
like to fire on new shelf surfaces using only the alumina hydrate. If
any kind of kiln wash has ever been applied, it tends to make snagging
points, and I had just as soon not have to deal with those. Granted,
once in a while I will have a pot run on me and stick glaze to the
shelf, but not often.
Good luck.
John Rodgers
Chelsea, AL
F Parker wrote:
> I am trying (operative word = "trying") to throw a set of eight large dinnerplates. Out of the eight I threw only three made it into the bisque kiln. I thought the three came through the bisque just fine, then I discovered a hairline crack about 2" long in one just below the rim on the inside.
> Most of the failures have happened during drying. Some were radial cracks in the rims. Others were complete separations of the rims from the plate bottoms -- again, during drying. The plates are thrown to approximately 12.5" diameters using 4 pounds of Standard #365 ^6 porcelain.
> It seems very, very slow drying under plastic helps. I throw using either a plaster bat or a particle board bat.
> I would very much appreciate any advice on how to improve my success ratio.
> Thank you,
> Fred Parker
>
>
>
>
>
>
Vince Pitelka on mon 1 sep 08
Craig Martell wrote:
"I cut the piece off and set all the plates in my damp box and
dry them slowly for about 2-3 days before turning. Turn them upside down as
soon as the rims are dry enough. I turn them and then place them upside
down on wareboards that are covered with paper to compensate for movement
during shrinkage." I bisque fire all my porcelain to cone 03 to give enough
strength to survive the quartz inversion on cooling. I think that cone 04
bisque is fine too."
To add to Craig's excellent advice, the drying is really critical with
porcelain. If the rim dries faster than the base, it shrinks and tilts up.
When the base stiffens and shrinks, it pulls the rim back down, but in doing
so it stretches and opens the clay on the inside of the curve where the base
of the plate meets the rim, and in bisque-firing or glaze-firing that area
develops cracks going partway around the plate at the outer edge of the
bottom or well of the plate. Remember that porcelain is very weak in the
bone-dry stage, so as the clay is drying, the particles can pull apart
easily. It is always a challenge to get a broad distribution of particle
sizes in a porcelain body. Having a narrower range of particles means less
contact points and more air voids, which means weaker bone-dry ware. Craig
is dead-on about bisque-firing porcelain higher, because that simply allows
a little more development of glassy-phase to reinforce what sintered
connections there are between particles. People often do not realize how
much weaker porcelain is than stoneware at the bone-dry or cone 08 or 06
bisque-fired stage. That weakness is responsible for many of the problems
encountered in working and firing porcelain.
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpitelka@dtccom.net; wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka
Ric Swenson on tue 2 sep 08
Vince,
I fear thou protest too much.
Some porcelain clays are EXTREMELY strong in the green state. The clay of JingDeZhen is VERY strong in the green state. One of the best I have ever seen.....and I have seen a few in the past 41 years.
There are bodies that can handle what you are trying to do. Bone dry porcelain is NOT necessarily "weak"....that particular body might be weak....but it does not have to be weak.
Lee will tell you that there is a way to do this.....in Japan.......
Chinese ....JingDeZhen potters work with a clay everyday that is extremely durable and hard in the green state. It is tough shit. I have never worked with such durable clay in the green state. all works are once fired........amazing clays from Gao Ling (kaolin)
The materials in your area define your work and ability to do some stuff.....that maybe others cannot duplicate. Materials do NOT travel from one area to another....glazes do not travel. Work with what you have and do the best you can with what you have to work with. Every area has its limitations.....in materials and minerals.....
That's why I am in China. And will stay here.
My 2 RMB
Ric
It depends on the formulation of the clay."...then fiery expedition be my wing, ..." -Wm. Shakespeare, RICHARD III, Act IV Scene III Richard H. ("Ric") Swenson, Teacher, Office of International Cooperation and Exchange of Jingdezhen Ceramic Institute, TaoYang Road, Eastern Suburb, Jingdezhen City.JiangXi Province, P.R. of China. Postal code 333001. Mobile/cellular phone : 86 13767818872 < RicSwenson0823@hotmail.com> http://www.jci.jx.cn/http://www.ricswenson.com
> Date: Mon, 1 Sep 2008 20:40:46 -0700> From: vpitelka@DTCCOM.NET> Subject: Re: Question for the porcelain gurus> To: CLAYART@LSV.CERAMICS.ORG> > Craig Martell wrote:> "I cut the piece off and set all the plates in my damp box and> dry them slowly for about 2-3 days before turning. Turn them upside down as> soon as the rims are dry enough. I turn them and then place them upside> down on wareboards that are covered with paper to compensate for movement> during shrinkage." I bisque fire all my porcelain to cone 03 to give enough> strength to survive the quartz inversion on cooling. I think that cone 04> bisque is fine too."> > To add to Craig's excellent advice, the drying is really critical with> porcelain. If the rim dries faster than the base, it shrinks and tilts up.> When the base stiffens and shrinks, it pulls the rim back down, but in doing> so it stretches and opens the clay on the inside of the curve where the base> of the plate meets the rim, and in bisque-firing or glaze-firing that area> develops cracks going partway around the plate at the outer edge of the> bottom or well of the plate. Remember that porcelain is very weak in the> bone-dry stage, so as the clay is drying, the particles can pull apart> easily. It is always a challenge to get a broad distribution of particle> sizes in a porcelain body. Having a narrower range of particles means less> contact points and more air voids, which means weaker bone-dry ware. Craig> is dead-on about bisque-firing porcelain higher, because that simply allows> a little more development of glassy-phase to reinforce what sintered> connections there are between particles. People often do not realize how> much weaker porcelain is than stoneware at the bone-dry or cone 08 or 06> bisque-fired stage. That weakness is responsible for many of the problems> encountered in working and firing porcelain.> - Vince> > Vince Pitelka> Appalachian Center for Craft> Tennessee Tech University> vpitelka@dtccom.net; wpitelka@tntech.edu> http://iweb.tntech.edu/wpitelka
_________________________________________________________________
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Kim Hohlmayer on tue 2 sep 08
This works for any clay I've used. Porcelain demands but my stonewares sure do better this way too though I don't usually go a month. --Kim H.
--- On Mon, 9/1/08, Christine Campbell wrote:
> From: Christine Campbell
> Subject: Re: Question for the porcelain gurus
> To: CLAYART@LSV.CERAMICS.ORG
> Date: Monday, September 1, 2008, 1:37 PM
> One process I totally misunderstood
> when learning about porcelain was
> "dry slowly".
>
> What's slow?
> A day, a week, longer?
>
> I thought I was going slowly until I
> visited a famous porcelain artist
> and found out he manipulates the drying
> so it takes a month or more. Huge wet
> boxes where work was gently turned and
> babied until it was dry.
>
> It was a thrill to visit since he was getting
> ready for a major show and every surface of
> his studio was covered with large snow white
> vases and bowls in various stages of the process.
>
> My work routinely dries for weeks now and
> the success rate has gone up.
>
> Chris Campbell - in North Carolina
>
> --
> Chris Campbell Pottery LLC
> 9417 Koupela Drive
> Raleigh NC 27615-2233
>
> Designs in Colored Porcelain
>
> 1-800-652-1008
> Fax : 919-676-2062
> website: www.ccpottery.com
> wholesale : www.wholesalecrafts.com
David McBeth on tue 2 sep 08
Porcelain drying slowly? Whats slowly, today I am glaze firing to C 10, =
heavy reduction (whats heavy, right!) medium sized platter/bowls =
apporximately 14 inches in diameter and 3 ish inches tall. These pots =
were thrown on Friday, trimmed Sunday afternoon, bisqued fired to a soft =
C 012 on Monday and, as I said being glazed fired today. Tomorrow I =
will unload the kiln and hopefully ship two or three to an exhibit in =
Maine. I'll report back about warping and cracks. More than a =
determinent amount of drying time, is knowing your clay because you have =
made many pots, paying atention to the drying conditions, throwing =
uniformly and a little luck too maybe. By the way, Standard Ceramics =
Grolleg Porcelain clay #257 is wonderful. I used some from Laguna =
called Elaine's Crystal Porcelain, I think, this summer. That too is a =
nice body, though the clay was very wet straight out of the box.
now, back to the studio, more pots to make so I can fire again this =
week!
Dave
David McBeth
330 B Gooch Hall
Department of Visual and Theatre Arts
University of Tennessee at Martin
Martin, Tennessee 38238
731-881-7416
http://davidmcbeth.blogspot.com
-----Original Message-----
From: Clayart on behalf of Christine Campbell
Sent: Mon 9/1/2008 12:37 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: Question for the porcelain gurus
=20
One process I totally misunderstood
when learning about porcelain was
"dry slowly".
What's slow?
A day, a week, longer?
I thought I was going slowly until I
visited a famous porcelain artist
and found out he manipulates the drying
so it takes a month or more. Huge wet
boxes where work was gently turned and
babied until it was dry.
It was a thrill to visit since he was getting
ready for a major show and every surface of
his studio was covered with large snow white
vases and bowls in various stages of the process.
My work routinely dries for weeks now and
the success rate has gone up.
Chris Campbell - in North Carolina
--
Chris Campbell Pottery LLC
9417 Koupela Drive
Raleigh NC 27615-2233
Designs in Colored Porcelain
1-800-652-1008
Fax : 919-676-2062
website: www.ccpottery.com
wholesale : www.wholesalecrafts.com
Lee Love on tue 2 sep 08
On Tue, Sep 2, 2008 at 3:12 PM, David McBeth wrote:
> These pots were thrown on Friday, trimmed Sunday afternoon, bisqued fired
>to a soft C 012
David. I soft bisque too. Do you sponge the porcelain before you
glaze to avoid pinholing?
May first throwing in the basement today. Chawan instead of
yunomi. Kintaro behind me on the floor while I work.
--
Lee Love in Minneapolis
http://mashikopots.blogspot.com/
http://claycraft.blogspot.com/
"Let the beauty we love be what we do.
There are hundreds of ways to kneel and kiss the ground." --Rumi
Doug Trott on wed 3 sep 08
Kintaro is a beautiful dog. I have run into him several times at the clay =
center=2C where he patrols. Not especially friendly=2C but not at all thre=
atening=2C he gives quiet little warning barks to Lee whenever he senses ..=
.well=2C pretty much anything! Ruf............ruf............ruf.........p=
erhaps it's sonar!
One of the few critters that doesn't warm to me quickly - I told Lee that K=
intaro must be an excellent judge of character....
Doug
> Date: Wed=2C 3 Sep 2008 19:09:22 +0200
> From: fa520033@SKYNET.BE
> Subject: Re: Question for the porcelain gurus
> To: CLAYART@LSV.CERAMICS.ORG
>=20
> waaaauw lee it is a beautifull dog
> ----- Original Message -----
> From: "Lee Love"
> To:
> Sent: Wednesday=2C September 03=2C 2008 2:00 PM
> Subject: Re: Question for the porcelain gurus
>=20
>=20
> > On Wed=2C Sep 3=2C 2008 at 2:15 AM=2C jean szostek =
wrote:
> >> hi lee what is kintaro greatings jean
> >> by the way kitaro i now=2C i like very much
> > Hi Jean=2C
> >
> > Thank you! Kintaro is my Akita. I brought him with me from
> > Japan. He is my helper in the studio. Stays up with me all night if
> > I am getting ready for a woodfiring or during the firing (In Japan=2C I
> > fired alone=2C only with his help.)
> >
> > You can see some photos here:
> >
> > http://akitas.blogspot.com/
> >
> > --
> > Lee Love in Minneapolis
> > http://heartclay.blogspot.com/
> > http://mashikopots.blogspot.com/
> > http://claycraft.blogspot.com/
> >
> > "Let the beauty we love be what we do.
> > There are hundreds of ways to kneel and kiss the ground." --Rumi
>=20
>=20
> -------------------------------------------------------------------------=
-------
>=20
>=20
>=20
> No virus found in this incoming message.
> Checked by AVG - http://www.avg.com
> Version: 8.0.169 / Virus Database: 270.6.15/1648 - Release Date: 2/09/200=
8
> 17:29
Sheila Tarshis on wed 3 sep 08
HI, I have used Standard 365 for a year now and find cracks and some
warping. When I called the technician at Standard, I asked her if they could
mix some molochite in the 365. She had planned to do just that and I bought
the remaining 400 lbs. It has made a difference and I am much more pleased
with the results.
Hope this helps.
Sheila
On Sun, Aug 31, 2008 at 8:47 PM, F Parker wrote:
> I am trying (operative word = "trying") to throw a set of eight large
> dinnerplates. Out of the eight I threw only three made it into the bisque
> kiln. I thought the three came through the bisque just fine, then I
> discovered a hairline crack about 2" long in one just below the rim on the
> inside.
> Most of the failures have happened during drying. Some were radial cracks
> in the rims. Others were complete separations of the rims from the plate
> bottoms -- again, during drying. The plates are thrown to approximately
> 12.5" diameters using 4 pounds of Standard #365 ^6 porcelain.
> It seems very, very slow drying under plastic helps. I throw using either
> a plaster bat or a particle board bat.
> I would very much appreciate any advice on how to improve my success ratio.
> Thank you,
> Fred Parker
>
>
>
>
jean szostek on wed 3 sep 08
hi lee what is kintaro greatings jean
by the way kitaro i now, i like very much
----- Original Message -----
From: "Lee Love"
To:
Sent: Wednesday, September 03, 2008 12:38 AM
Subject: Re: Question for the porcelain gurus
> On Tue, Sep 2, 2008 at 3:12 PM, David McBeth wrote:
>
>> These pots were thrown on Friday, trimmed Sunday afternoon, bisqued fired
>>to a soft C 012
>
> David. I soft bisque too. Do you sponge the porcelain before you
> glaze to avoid pinholing?
>
> May first throwing in the basement today. Chawan instead of
> yunomi. Kintaro behind me on the floor while I work.
>
> --
> Lee Love in Minneapolis
> http://mashikopots.blogspot.com/
> http://claycraft.blogspot.com/
>
> "Let the beauty we love be what we do.
> There are hundreds of ways to kneel and kiss the ground." --Rumi
--------------------------------------------------------------------------------
No virus found in this incoming message.
Checked by AVG - http://www.avg.com
Version: 8.0.169 / Virus Database: 270.6.15/1648 - Release Date: 2/09/2008
17:29
Bonnie Staffel on wed 3 sep 08
Fred, might I suggest that you wax the rims with wax emulsion, both =
topside
and underside to slow the drying at that point. Also the plaster may be
drawing the moisture unevenly as well, maybe drying the center before =
the
rim.=20
You might also check how much water you are using in throwing the plates =
and
cut back on that as well.
I use oiled Masonite bats which work very well as they don't dry the =
center
rapidly and I then wax the rims as soon as thrown. Seems it equalizes
everything.
Bonnie Staffel
http://webpages.charter.net/bstaffel/
http://vasefinder.com/bstaffelgallery1.html
DVD Throwing with Coils and Slabs
DVD Introduction to Wheel Work
Charter Member Potters Council
Lee Love on wed 3 sep 08
On Wed, Sep 3, 2008 at 2:15 AM, jean szostek wrote:
> hi lee what is kintaro greatings jean
> by the way kitaro i now, i like very much
Hi Jean,
Thank you! Kintaro is my Akita. I brought him with me from
Japan. He is my helper in the studio. Stays up with me all night if
I am getting ready for a woodfiring or during the firing (In Japan, I
fired alone, only with his help.)
You can see some photos here:
http://akitas.blogspot.com/
--
Lee Love in Minneapolis
http://heartclay.blogspot.com/
http://mashikopots.blogspot.com/
http://claycraft.blogspot.com/
"Let the beauty we love be what we do.
There are hundreds of ways to kneel and kiss the ground." --Rumi
jean szostek on wed 3 sep 08
waaaauw lee it is a beautifull dog
----- Original Message -----
From: "Lee Love"
To:
Sent: Wednesday, September 03, 2008 2:00 PM
Subject: Re: Question for the porcelain gurus
> On Wed, Sep 3, 2008 at 2:15 AM, jean szostek wrote:
>> hi lee what is kintaro greatings jean
>> by the way kitaro i now, i like very much
> Hi Jean,
>
> Thank you! Kintaro is my Akita. I brought him with me from
> Japan. He is my helper in the studio. Stays up with me all night if
> I am getting ready for a woodfiring or during the firing (In Japan, I
> fired alone, only with his help.)
>
> You can see some photos here:
>
> http://akitas.blogspot.com/
>
> --
> Lee Love in Minneapolis
> http://heartclay.blogspot.com/
> http://mashikopots.blogspot.com/
> http://claycraft.blogspot.com/
>
> "Let the beauty we love be what we do.
> There are hundreds of ways to kneel and kiss the ground." --Rumi
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17:29
Ron Roy on thu 4 sep 08
Hi Fred,
I used to throw a lot of plates in porcelain - keep the rim thick so they
don't dry too fast and really compress them in from the outside - stretched
porcelain will really shrink a lot and cause all kinds of problems. You can
trim them after they are leather hard. It's a good way to get the rims
flatter if you want that type of plate.
They can also crack during cooling during a bisque firing - at the quartz
inversion - keep them near the top of the kiln so they don't cool as fast -
or control cool from 700 down to 500C.
RR
>I am trying (operative word = "trying") to throw a set of eight large
>dinnerplates. Out of the eight I threw only three made it into the bisque
>kiln. I thought the three came through the bisque just fine, then I
>discovered a hairline crack about 2" long in one just below the rim on the
>inside.
Most of the failures have happened during drying. Some were
>radial cracks in the rims. Others were complete separations of the rims
>from the plate bottoms -- again, during drying. The plates are thrown to
>approximately 12.5" diameters using 4 pounds of Standard #365 ^6
>porcelain.
It seems very, very slow drying under plastic helps. I throw
>using either a plaster bat or a particle board bat.
I would very much
>appreciate any advice on how to improve my success ratio.
Thank you,
Fred
>Parker
Ron Roy
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
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