Kevin P. O'Hara on wed 4 dec 96
Hello again everyone,
Has anyone out there applied there glaze to a greenware piece and then fired
their work. I read about it in a book and it makes me curious. One could
save a lot of money in fuel costs. The book said something about applying
glaze to the whole piece rather than glazing all of the insides of all your
pots and then glazing the outsides, otherwise the pots would crack from
uneven expansion. Does anyone have any wisdom that they would like to share
on the this subject? What kind of clay is best. What type of firing works
best: high fire/low fire, oxidation/reduction. What type of glazes works
best. Can you do once firing with an electric? Does anyone have any success
or failure stories?
Thanks
Kevin P. O'Hara
ohara@indy.cp.lucent.com
Lisa on thu 5 dec 96
Kevin P. O'Hara wrote:
Can you do once firing with an electric? Does anyone have any success
> or failure stories?
I have done once-fire at ^6 electric several times with no problems at
all. The biggest problem I've found is when you're working in a communal
studio and the person loading the kiln doesn't know your glazed piece
is greenware...and breaks it. :(
Eleanora Eden on thu 5 dec 96
Hi Kevin and all,
Interesting this should come up as for the first time I am
double-dipping my dry greenware in somewhat diluted underglaze
to get a good coverage and I always thought you couldn't do this because
the ware was supposed to self-destruct in the liquid. Well, it worked fine.
Dipped once, let it dry, dipped again. No problem. So I would say go
for it. Play around with the thickness of the glaze as it will take up
different than biscware.
Eleanora
Eleanora Eden 802 869-2003
Paradise Hill
Bellows Falls, VT 05101 eden@maple.sover.net
[the address fga@world.std.com is temporary. My mailbox at
eden@maple.sover.net still works -- do not change address books]
Laura Freedman on thu 5 dec 96
Kevin P. O'Hara wrote:
>
> ----------------------------Original message----------------------------
> Hello again everyone,
>
> Has anyone out there applied there glaze to a greenware piece and then fired
> their work. I read about it in a book and it makes me curious. One could
> save a lot of money in fuel costs. The book said something about applying
> glaze to the whole piece rather than glazing all of the insides of all your
> pots and then glazing the outsides, otherwise the pots would crack from
> uneven expansion. Does anyone have any wisdom that they would like to share
> on the this subject? What kind of clay is best. What type of firing works
> best: high fire/low fire, oxidation/reduction. What type of glazes works
> best. Can you do once firing with an electric? Does anyone have any success
> or failure stories?
>
> Thanks
>
> Kevin P. O'Hara
> ohara@indy.cp.lucent.com
----------
Kevin, I am no expert on this subject but I have tried once fired items
2 or 3 times and was successful. Probably beginners luck. I used
Standard Ceramic 112 clay and cannot remember what glazes, it was a
while ago. I dipped the pots VERY carefully. I didn't break any but it
would be so easy for that to happen. That's why I don't do it more
often.
Tony Hansen on fri 6 dec 96
Once firing works but it's a real 'can of worms'.
I've worked with it an assisted many companies who have tried.
If you are small-scale, I think you will spend more energy refiring pieces
with crawled glazes and redoing others that did not work that you would by
bisque firing. Bisque ware is so much better to work with.
--
=================================================================
Tony Hansen, IMC - Publishers of INSIGHT/FORESIGHT/Magic of Fire
Get INSIGHT 5 beta at http://digitalfire.com/insight5.htm
Betsy Parker on fri 6 dec 96
Hi, Kevin - I have been working predominantly with ^6 stoneware clays for
about 11 years now. My college background is not in clay and most of what I
have learned has been "seat of the pants", reading every single thing I can
get my hands on about clay and listening to every person I meet who works in
clay. I started once-firing before I knew it was so challenging and now can
imagine doing nothing else. Almost all my work is once-fired. I brush glaze
most, though, because most of my pieces are highly-textured animal forms and
brush-glazing allows texture to remain intact with the clay body adding
contrast. If you try this, please wear a mask. The glaze dries so quickly
on the dry body, chemical dust is very easy to inhale while brush glazing. I
fire electric and have had no problems. You do have to experiment with the
thickness of the glaze to make application easier and to avoid cracking the
piece. I have some pieces that are stained, then glazed - they have to be
thoroughly dried between the two processes to avoid breaking down the clay.
Also, if you want to try more than one coat, you have to dry it in between.
I rarely find it necessary to use more than one coat - thus avoiding more
chances of breakage. You do sometimes get erratic coverage with brush
glazing, but I've had no problem spot glazing and refiring when that happens.
And over the years, I've worked out patterns of brushing on the glazes which
makes it less likely I have thicker and thinner application spots. I use so
many different colors that I use a broad range of commercial glazes from
several different sources - no problems noted there, except that blues need
heavier application or you get bluish browns! I've used at least 7 different
^6 stoneware bodies (all colors), ^6 porcelains, colored porcelains, and one
^06 body using once-firing and have had no problems I couldn't find a
solution to (so far!!).
I hope this is of some use to you. If I can pass on anything else I've
learned just ask. And my thanks to all of you very learned Clayarters who are
continuing my education in this wonderful stuff, clay!!!
Enjoy!!! ~Betsy getting colder in NJ
Diane S. Zubrick on fri 6 dec 96
I once fire all my pottery. I work with red clay, slips and clear glaze.
It saves so much time, especially since I do pottery for shows. The end
product is just the same.
But I do have mostly flat things; ornaments, jewelry, hangings and
plates. Yes, handling is a problem - I have made fingernail marks many
a time. I pick up a plate with two hands, also. I brush on all my
glazes. I dry my work in the sun or on top of a hot kiln to be sure they
are bone dry.
Dust can be a problem, especially since I sand my edges to get any stray
slip off the red clay. I use a big soft brush to get all the dust off
before I glaze. I also spray my work lightly with water before I brush
the clear glaze over the slips - it helps eliminate pinholes.
I have written about this with more detail before and do not want to
repeat. If you want more details, just write. Experiment with it, and
see if it works for your clay and glazes.
Diane Schwob Zubrick - the shows are FINALLY done for the year!!!
Applecreek Pottery
Centerville, Ohio (south of Dayton)
dianezubrick@juno.com
Craig Martell on fri 6 dec 96
Hi Kevin: I think that single firing is like any other ceramic process, it
can be vexing at first but with learning and experience it gets easier and is
quite enjoyable. Most of the single fire potters I know like it more for its
spontaneous nature and the quickness with which you can get a pot through the
process. But, fuel savings are a good thing too.
You can use most any type of firing process to do once fire. I would think
though that Raku would be kind of tough, but not impossible. I single fire
large pots in the salt kiln and my wife single fires to cone 10 in the
electric. She sprays most of her glazes and has very few losses due to the
glazing process. Spraying probably causes the least amount of stress to raw
ware, but you can be sucessful with any of the other methods of applying
glaze. Brushing, pouring, dipping, trailing, all work. If you choose to
glaze one side of the pot at a time, such as lining a mug or cup, you can
alleviate the stresses due to moisture differential by misting the outer wall
with a spray bottle of water. I do this and it works well.
One thing that is important to determine is: When are you going to glaze the
pot? Some folks like to glaze leather hard ware and others like to glaze
bone dry. I personally like the bone dry stage for glazing. Almost any type
of glaze used on bisqueware will work, although most agree on a minimum of
about 10% clay in the glaze. The ware has a bit more strength at bone dry
and you don't have to worry about uneven moisture content causing cracks. If
you choose to glaze at the leather hard stage, the glazes must contain much
more clay or they will flake off the pieces because of the shrinkage that
takes place in the ware between leather hard and bone dry. The glaze must
contain enough clay that it shrinks along with the pot.
You must also pay more attention to the making of the ware. If the pieces
are thrown, care must be taken to achieve a fairly even wall thickness. The
walls don't have to be perfect, but the closer you are the higher the chances
of success. You must really strive to eliminate THIN spots is the walls. If
there are sections that are too thin, there is a great chance of a crack
starting there. The walls must have adequate compression, inside and out.
Ribbing, helps prevent cracks. The denser the wall of the pot, the less
moisture it will absorb. Which brings me to another point. Very "open"
claybodies sometimes absorb moisture too quickly and fail. It is beneficial
to use denser, perhaps finer sized claybodies in single firing. I have
single fired a lot of porcelain and it performs very well.
There is more to write on this subject, I haven't even broached the subject
of firing, but this may be enough for now and I'm sure there are others who
will comment on the process. Don't be afraid to try this process, you may be
very pleasantly surprised!
Kind Regards, Craig Martell-Oregon
Lili Krakowski on sat 7 dec 96
Andrew Holden in The Self-Reliant Potter (There is more than one book
with that title, so double check at PL--the book, by the way is out of
print) and Denis Parks in his book speak of it. From my reading any
glaze with a high clay content or which holds 8%-13% bentonite
(replacing some of the clay or spar) should work.
I apply the glaze thickly with a soft brush, right after I finish trimming.
One must be careful not to resoften the clay too much or the pot will
distort too easily when handled.
One must make tests and experiement. And for me the key to success has
been immensely slow firing. I do not do a whole lot of once firing. But
for certain things I find it invaluable.
As to gorgeous? Apparently Lucie Rie always once fired.
Lili Krakowski
lkkrakow@edisto.cofc.edu
On Wed, 4 Dec 1996, Kevin P. O'Hara wrote:
> ----------------------------Original message----------------------------
> Hello again everyone,
>
> Has anyone out there applied there glaze to a greenware piece and then fired
> their work. I read about it in a book and it makes me curious. One could
> save a lot of money in fuel costs. The book said something about applying
> glaze to the whole piece rather than glazing all of the insides of all your
> pots and then glazing the outsides, otherwise the pots would crack from
> uneven expansion. Does anyone have any wisdom that they would like to share
> on the this subject? What kind of clay is best. What type of firing works
> best: high fire/low fire, oxidation/reduction. What type of glazes works
> best. Can you do once firing with an electric? Does anyone have any success
> or failure stories?
>
> Thanks
>
> Kevin P. O'Hara
> ohara@indy.cp.lucent.com
>
Kevin P. O'Hara on sat 7 dec 96
Subject: Re: Once fired
----------------------portions of the------Original
message--------------------
Hi Kevin: I think that single firing is like any other ceramic process, it
can be vexing at first but with learning and experience it gets easier and
is
quite enjoyable. Most of the single fire potters I know like it more for
its
spontaneous nature and the quickness with which you can get a pot through
the
process. ...
.... Don't be afraid to try this process, you may be
very pleasantly surprised!
Kind Regards, Craig Martell-Oregon
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Thank you very much for the information you and everyone else has shared; it
is extremely useful to not only my self, but many others also.
Sincerely
Kevin P. O+Hara
Judy A Brager on sat 7 dec 96
I would also like to try single firing but I work with C6 paper clay from
Clay Arts in Tacoma, WA. I'm concerned about what will happen when the
paper burns out. Has anyone tried single firing paper clay?
TIA, Judy (hjbrager@juno.com)
lkkrakow@edisto.cofc.edu on sun 8 dec 96
From: Lili Krakowski
----------------------------Original message----------------------------
Andrew Holden in The Self-Reliant Potter (There is more than one book
with that title, so double check at PL--the book, by the way is out of
print) and Denis Parks in his book speak of it. From my reading any
glaze with a high clay content or which holds 8%-13% bentonite
(replacing some of the clay or spar) should work.
I apply the glaze thickly with a soft brush, right after I finish
trimming.
One must be careful not to resoften the clay too much or the pot will
distort too easily when handled.
One must make tests and experiement. And for me the key to success has
been immensely slow firing. I do not do a whole lot of once firing. But
for certain things I find it invaluable.
As to gorgeous? Apparently Lucie Rie always once fired.
Lili Krakowski
lkkrakow@edisto.cofc.edu
On Wed, 4 Dec 1996, Kevin P. O'Hara wrote:
> ----------------------------Original
message----------------------------
> Hello again everyone,
>
> Has anyone out there applied there glaze to a greenware piece and
then fired
> their work. I read about it in a book and it makes me curious. One
could
> save a lot of money in fuel costs. The book said something about
applying
> glaze to the whole piece rather than glazing all of the insides of
all your
> pots and then glazing the outsides, otherwise the pots would crack
from
> uneven expansion. Does anyone have any wisdom that they would like
to share
> on the this subject? What kind of clay is best. What type of firing
works
> best: high fire/low fire, oxidation/reduction. What type of glazes
works
> best. Can you do once firing with an electric? Does anyone have any
success
> or failure stories?
>
> Thanks
>
> Kevin P. O'Hara
> ohara@indy.cp.lucent.com
>
ohara@indy.cp.lucent.com on sun 8 dec 96
From: "Kevin P. O'Hara"
----------------------------Original message----------------------------
Subject: Re: Once fired
----------------------portions of the------Original
message--------------------
Hi Kevin: I think that single firing is like any other ceramic
process, it
can be vexing at first but with learning and experience it gets easier
and
is
quite enjoyable. Most of the single fire potters I know like it more
for
its
spontaneous nature and the quickness with which you can get a pot
through
the
process. ...
.... Don't be afraid to try this process, you may be
very pleasantly surprised!
Kind Regards, Craig Martell-Oregon
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Thank you very much for the information you and everyone else has
shared; it
is extremely useful to not only my self, but many others also.
Sincerely
Kevin P. O+Hara
LINDA BLOSSOM on sun 8 dec 96
Dear Tony,
I yield to you on every technical issue, but in this case my own
experience says differently. I use over a hundred different glazes, (I've
never met a glaze I couldn't single fire) and fire both flat and vertical
forms. I brush and spray glazes. I do not have a problem with pinholes or
crawling...I have glazed thick and very thin pieces. I fire in both gas
and electric, all to cone 6. Everything single
fired. I would never consider bisque.
Linda Blossom
2366 Slaterville Rd.
Ithaca, NY 14850
blossom@lightlink.com
http://www.artscape.com
607-539-7912
Diane S. Zubrick on mon 9 dec 96
I guess the bottom line is on this "once fired" issue is to experiment
and see what works for your clay, glazes and kiln. Linda seems to have
the broadest experience with different kilns, glazes and shapes.
Another person has had success with once firing stoneware. I once fire
with my redware - red clay and lowfire, and the technique is always
consistent. No surprises when I open the kiln. I have never lengthened
the firing time - I take my work up to temperature in a very short time.
I would never bisque again, as Linda also stated. This process did not
work out for some of you, at least you experimented and found out the
result! For those that have never tried it; take a pot or a scrap,
give it a shelf of its own, and see the results. Just be sure that the
clay it is very dry. (It will blow up if the clay is damp!) Have fun!
Think of all the hours and energy you will save not having to run the
same artwork through your kiln twice!
Diane Schwob Zubrick
Applecreek Pottery
Centerville, Ohio
Tony Hansen on mon 16 dec 96
>LINDA BLOSSOM wrote:
>I use over a hundred different glazes, (I've
>never met a glaze I couldn't single fire)
Wow. I guess I must yield to your experience. I am soured to the once
fire process mostly by the fragility of thin walled
pieces, however, I did
work for an electrical porcelain plant that made millions of pounds of
product a year, all glazed green and once fired to cone 11. It was a
necessity there to save fuel costs because they are so heavy.
--
=================================================================
Tony Hansen, IMC - Publishers of INSIGHT/FORESIGHT/Magic of Fire
Get INSIGHT 5 beta at http://digitalfire.com/insight5.htm
Bill Amsterlaw on sat 21 dec 96
Hi Linda Blossom and other Clayarter's:
I thought I would start learning what I can about once-firing. I have done
some reading about it ... so now I will try to make it work for me. I fire
stoneware to cone 9.
1. My efforts to dip or pour glaze on thin, bone-dry work was a disaster.
The clay soaked up water from the glaze and collapsed.
2. I read about glazing in the leather-hard state and thought that might be
the way to go. The leather-hard clay would tend to absorb less water than
bone-dry clay:
** Ruggles and Rankin: The Rock Creek Climbing Kiln - part II in
Studio Potter June 1994.
But when I applied my glazes to leather-hard clay, they all shivered right off
the clay as it dried. I realized that I would have to re-formulate my glazes
to contain more bentonite or ball clay so that it would shrink in concert with
the clay.
But if I modified my glazes, would I then have problems applying the same
glazes to bisque? If I wanted to be able to glaze both raw and bisque would I
need two separate sets of glazes? Too many buckets!
3. Then I heard that people such as Steven Hill do their glazing in the
bone-dry state. To keep things from falling apart, you make STURDY pots ...
you don't make the walls too thin. Since bone-dry pots are not going to do
much shrinking, I reasoned that I could apply the same glazes that I would
apply to bisque and not have to worry about the glaze shivering off. So I
went back to bone-dry glazing.
Results:
Ok so I made up a bunch of goblets and raw-glazed them all:
* Only 10% collapsed during the glazing - not too bad: need to make them
thicker.
* The glaze went on a bit too thick. I guess this means the leather-hard
clay is more absorbent than bisque.
* None of the glazes shivered off.
* Bad news: The glaze crawled badly on every pot. I think the crawling
occurred because the too-thick glaze cracked and lifted off the clay. Maybe
I just need to apply the glaze a lot thinner. Back to the drawing board....
I am trying to get a copy of Steven Hill's article on his once-firing
technique from CM Jan 1986 - haven't seen it yet. I hear that Linda Blossom
and others have no problems with pots collapsing, or glaze shivering off, or
crawling when they glaze unfired clay. So, there is obviously something very
crucial to success in this process that I haven't figured out yet. What is
it?
1. Do you glaze in the leather-hard state or the bone-dry state?
2. Do you mostly spray your glazes? Do you avoid dipping and pouring?
3. Do you need to add something to your glazes to assure adherence to
bone-dry clay - such as CMC gum or veegum? Would it help to add bentonite
would help?
4. Do you have to apply glazes more thinly than you would on bisque?
I will keep trying to learn to raw glaze successfully and post my discoveries.
I would appreciate any practical suggestions anyone would like to make.
- Bill Amsterlaw (wamster@msn.com)
Plattsburgh, NY
------------------------------
On Sun, 8 Dec 1996 21:59:45 EST LINDA BLOSSOM wrote:
>>
I yield to you on every technical issue, but in this case my own
experience says differently. I use over a hundred different glazes, (I've
never met a glaze I couldn't single fire) and fire both flat and vertical
forms. I brush and spray glazes. I do not have a problem with pinholes or
crawling...I have glazed thick and very thin pieces. I fire in both gas and
electric, all to cone 6. Everything single fired. I would never consider
bisque.
<<
Craig Martell on sun 22 dec 96
In a message dated 96-12-21 09:39:08 EST, Bill wrote:
<< Results:
Ok so I made up a bunch of goblets and raw-glazed them all:
* Only 10% collapsed during the glazing - not too bad: need to make them
thicker. >>
Sometimes raw ware can absorb water too quickly. If you are using an "open",
grogged stoneware for example, this could be the problem. Using a rib to
smooth and "close" the clay can slow down the rate of aborbtion and it will
help stengthen and compress the ware as well. A bit of extra compression,
during forming, is very beneficial to raw glazed ware. I've seen lots of
cracks start at deep throw rings.
<off
the clay as it dried. >>
Bill: Excuse my nit picking, but shivering isn't the correct term here.
Shivering is a post firing glaze fault where glazes flake off rims and
handles, as well as other places, taking some of the claybody as well. I
think the correct term here is probably "flaking". There has been a little
confusion in past posts about shivering and I only offer this info in the
spirit of keeping our terms sorted out so we know what we're all talking
about.
Your post shows that you are doing a LOT of work with raw glazing. You are
being observant, methodical, and curious, which will all lead to greater
understanding and success. Keep up the good work.
Kind Regards, Craig Martell-Oregon
Diane S. Zubrick on sun 22 dec 96
Bill,
I glaze my pieces when they are bone dry and spray lightly with water to
prevent pinholes. I only brush on my glazes and I am using low fire
clear and a few glazes, all commercial.
My pieces are flat or slightly curved and I am only glaze one side and
the edges. I do not add anything to the glazes and put on the same
coverage as I would bisque.
We are certainly using different glazes, temperatures, clay and
forms...so I may not be much help.
Diane Schwob Zubrick
Applecreek Pottery
Centerville,Ohio
Louise K. Condon on mon 23 dec 96
On Sun, 22 Dec 1996, Diane S. Zubrick wrote:
> ----------------------------Original message----------------------------
> Bill,
>
> I glaze my pieces when they are bone dry and spray lightly with water to
> prevent pinholes. I only brush on my glazes and I am using low fire
> clear and a few glazes, all commercial.
>
> My pieces are flat or slightly curved and I am only glaze one side and
> the edges. I do not add anything to the glazes and put on the same
> coverage as I would bisque.
>
> We are certainly using different glazes, temperatures, clay and
> forms...so I may not be much help.
>
> Diane Schwob Zubrick
> Applecreek Pottery
> Centerville,Ohio
Diane, Have you tried this for RAKU? Rikki=LCON@LOC.GOV>
Susan Ammann on tue 24 dec 96
I've been single firing for about 15 years now and thought I would
try to share a little of what I've learned.
First of all, choice of clay body is very important. I use B-mix.
More open bodied stonewares did not work for me.
I glaze at bone dry usually inside first and allow the glaze to dry
COMPLETELY usually overnight. Then I start glazing exteriors and
allow each coat to dry completely again (as in no longer cold to the
touch). I add about 5% bentonite to a glaze receipe and mix my
glazes to about the consistency of medium cream.
Gentle handling is of course very important to greenware but I
haven't found it necessary to throw or construct slab pieces any
thicker than what is ordinarily found.
I fire to ^10R at a very slow rate, i.e. candle for a couple of
hours then at about 1# pressure overnight. By morning my kiln is up
to about ^06 and I begin the glaze and reduction part of my firing.
The firing is generally completed by 5:00 pm. But that's another
whole chapter.
So that's it in a nutshell (a very small nutshell).
Hope this helps.
Susan Ammann
Taos, N.M.
Susan Ammann
Susanfam@laplaza.org
Diane S. Zubrick on tue 24 dec 96
I have had no experience with "once fire" and Raku. I have just done the
technique with low fire clay and glazes.
Diane Schwob Zubrick
Applecreek Pottery
Centerville, Ohio
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