Eric Yoder on wed 26 feb 97
I am interested in singlefiring some pots and was wondering what the
best way to go about it is. Do I glaze when the pots are leather hard
or bone dry? Should I add bentonite to the glaze and if so how much?
If there are any other tips please include them.
Thanks, Eric
=================================
Yoder's Valley Pottery
eyoder@valkyrie.net
http://www.valkyrie.net/~eyoder/
=================================
Linhares, Paul on fri 28 feb 97
Hi Eric
I have been doing some single firing tests lately and my regular glaze
(13% EPK) works just fine if it is applyed to bone dry ware. I've also
started some triaxial blends to try to find a semi matt glaze that I can
apply to wet pieces.
Paul in Coshocton,Ohio
Berry Silverman on sun 9 may 99
If I want to experiment with one or two pieces for
single firing, cone 05, should I put them in a bisque
load or glaze load?
===
Berry Silverman,
Berryware, Tucson, Arizona
berrysilverman@yahoo.com
_________________________________________________________
Do You Yahoo!?
Get your free @yahoo.com address at http://mail.yahoo.com
dave morrison on mon 10 may 99
depends, are these glazed pots?? many low fire reds will burn out due to
gasses given off by greenware as it bisques.
-----Original Message-----
From: Berry Silverman
To: CLAYART@LSV.UKY.EDU
Date: Sunday, May 09, 1999 9:58 AM
Subject: Once firing
----------------------------Original message----------------------------
If I want to experiment with one or two pieces for
single firing, cone 05, should I put them in a bisque
load or glaze load?
===
Berry Silverman,
Berryware, Tucson, Arizona
berrysilverman@yahoo.com
_________________________________________________________
Do You Yahoo!?
Get your free @yahoo.com address at http://mail.yahoo.com
Khaimraj Seepersad on mon 10 may 99
If you have not done this before , these are your questions ,
[ 1 ] Are you firing the kiln with only these two pieces [ incase
they explode ] ?
[ 2 ] Do you bisque at 05 or glaze at 05 ?
[ 3 ] Will your glaze run at 05 ?
[ 4 ] What is you clay body's mix ?
Lastly , you may have to fire more slowly ,
especially before 600 to 700 deg. c.
Ria Clara .
-----Original Message-----
From: Berry Silverman
To: CLAYART@LSV.UKY.EDU
Date: 09 May 1999 7:55
Subject: Once firing
----------------------------Original message----------------------------
If I want to experiment with one or two pieces for
single firing, cone 05, should I put them in a bisque
load or glaze load?
===
Berry Silverman,
Berryware, Tucson, Arizona
berrysilverman@yahoo.com
_________________________________________________________
Do You Yahoo!?
Get your free @yahoo.com address at http://mail.yahoo.com
John Fazzino on mon 10 may 99
In a message dated 5/9/99 1:56:18 PM, berrysilverman@yahoo.com writes:
<<
If I want to experiment with one or two pieces for
single firing, cone 05, should I put them in a bisque
load or glaze load? >>
Barry, Whatever you call it, a single fire must be treated like a bisque fire
at first, for obvious reasons. If you are only going to 05 fire it like a
bisque. If you fire too fast, pieces could blow up.
John Fazzino
Joy Holdread on mon 10 may 99
In a message dated 5/9/99 10:56:15 AM US Mountain Standard Time,
berrysilverman@yahoo.com writes:
>
> If I want to experiment with one or two pieces for
> single firing, cone 05, should I put them in a bisque
> load or glaze load?
I've heard greenware in a kiln affects red colors as in they fade to clear.
I'd try it in a bisque & try a few reds just to see what happens. I'd be
careful about risking a glaze load of colors I know your buyers don't
tolerate color variations.
JOY
Nanci Bishof on tue 11 may 99
I often mix the load so as not to waste kiln space. Has not ever seemed to
make a significant difference, but I fire an electric kiln. You could put the
bisque & glazeware on different shelves in the same firing.
Hope this helps,
nanci
Cheryl Tall on wed 12 may 99
Dear Berry:
Hi Berry:
Most of my large scale coil built figurative sculpture is once fired. I
glaze fire to cone 04 and also include bisque in the load if I have some
that needs to be fired. Important point - greenware must be bone dry,
really, really dry, before glazing and firing. I use slips, terra
sigillata, oxides, commercial glazes and hand made low fire glazes and
apply them all at the same time. Some glazes will crawl on greenware,
so you need to do testing.
I also teach at a community college. Sometimes a student will forget
that they haven't bisque fired the piece and will glaze it. We glaze
fire to cone 6. Frequently this piece blows up and sticks to all the
glazed pottery. These are usually thick pieces and possibly not dry
enough.
My work can be viewed at http://www.streetfestflorida.com, or in the
Studio Potters ad in Ceramic Monthly.
Cheryl Tall
carrie or peter jacobson on fri 2 jul 99
Ababy, You can single-fire pretty much any clay and any glaze, though the
purer the clay and the better the glaze fit, and better your results will
be.
There is a wonderful book on single firing, called (ta-dum) "Single Firing;
the pros and cons" by Fran Tristram. This is available from The Potters
Shop, and probably elsewhere, I imagine.
I've found I have pretty good karma with single firing, or at least, I did,
until that was pointed out to me. Ironically, or coincidentally, I have had
trouble with it since.
The good parts of single firing are the cost savings and time savings, and
the fact that you don't have to touch bisqueware. Also, the glaze becomes
more a part of the piece, when everything works right, than a material that
covers the piece.
The downside of single firing is that your explosion rate is higher than if
you do traditional firing. Any impurity in the clay will cause a crack or a
blowup. And since you are always doing a glaze firing, an explosion is way
more likely to ruin an entire kiln load. I have had explosions, cracks and
sags on the way up, and on the way down, even if I fire down. I have had
the best luck with porcelain.
The act of glazing is, in my experience, more difficult if you single-fire.
Tristam claims otherwise, but my clumsy and inexperienced hands have broken
a number of pieces while glazing them. I am finding, too, that the thinner
I throw, the more problems I have, single-firing.
In general, your best glaze-body fit for single firing will be glazes with
relatively high clay contents, that adhere well to the dryware, and don't
penetrate too awfully deep.
Also in general, fire slowly, and cool even more slowly.
Best of luck,
Carrie
Carrie Jacobson
Pawcatuck, CT
mailto:jacobson@brainiac.com
Ray Aldridge on sat 3 jul 99
At 09:20 AM 7/2/99 EDT, you wrote:
>
>The downside of single firing is that your explosion rate is higher than if
>you do traditional firing. Any impurity in the clay will cause a crack or a
>blowup.
I'm no expert, so I might easily be completely wrong, but I doubt that
"impurities" in the clay have anything to do with cracks or, especially,
explosions in single firing. Explosions are almost certainly related to
water in the clay-- imperfect drying or too-fast firing. I've never seen a
plausible example of any other reason for an exploding pot, except for pots
that shatter after firing from the effects of extreme glaze compression.
Cracks, in my opinion, are unlikely to originate from impurities, though
I've seen small cracks around a pebble inadvertently left embedded in the
wall of a pot made from as-dug stoneware.
I've heard of clay instructors who guilt the dickens out of their students
by claiming that a blown-up pot was the result of inadequate wedging or
some other such mumbojumbo. Not so-- it's the fault of the person who sets
and fires the kiln. A blow-up might result from a pot too thick for the
firing schedule, but again, the person who set the kiln should have noticed
how heavy it was and slowed down the firing.
Ray
Lori Pierce on sun 4 jul 99
When I single fired the only change I made in my glazes was to change all
china clay (EPK) to ball clay and use an hydrometer to make certain that the
glaze was the correct consistency...1.35 to1.4 usually, maybe up to 1.7; I
found I preferred to glaze the ware bone dry. Much easier than running
around trying to get to each pot at the "proper" stage in its drying
cycle...and yes I had my share of sagging pots as I learned, but it didn't
take long. There is a book by Dennis Parks , A potter's Guide to Raw Glazing
and Oil Firing, that I found useful. I do think a fairly non absorbent and
dense clay body helps also, tho I'd try the one I liked using best
first...it will probably work. Good luck..I remember what a great sense of
accomplishment that first electric firing was! Lori in New Port richey Fl.
-----Original Message-----
From: Ray Aldridge
To: CLAYART@LSV.UKY.EDU
Date: Saturday, July 03, 1999 9:45 AM
Subject: Re: once firing
----------------------------Original message----------------------------
At 09:20 AM 7/2/99 EDT, you wrote:
>
>The downside of single firing is that your explosion rate is higher than if
>you do traditional firing. Any impurity in the clay will cause a crack or a
>blowup.
I'm no expert, so I might easily be completely wrong, but I doubt that
"impurities" in the clay have anything to do with cracks or, especially,
explosions in single firing. Explosions are almost certainly related to
water in the clay-- imperfect drying or too-fast firing. I've never seen a
plausible example of any other reason for an exploding pot, except for pots
that shatter after firing from the effects of extreme glaze compression.
Cracks, in my opinion, are unlikely to originate from impurities, though
I've seen small cracks around a pebble inadvertently left embedded in the
wall of a pot made from as-dug stoneware.
I've heard of clay instructors who guilt the dickens out of their students
by claiming that a blown-up pot was the result of inadequate wedging or
some other such mumbojumbo. Not so-- it's the fault of the person who sets
and fires the kiln. A blow-up might result from a pot too thick for the
firing schedule, but again, the person who set the kiln should have noticed
how heavy it was and slowed down the firing.
Ray
Donn Buchfinck on mon 5 jul 99
If people are interested in once firing thier work, a good person to contact
is Steven Hill in Kansas city
he has made his carreer out of single firing his work and he uses b-mix as
his clay now.
I think it is important to say that he glazes when bone dry,
where as someone like Micheal Simon from georgia who once fires also, glazes
when his pots are leather hard.
I know micheal used gustin shino to line his pots with, it fits great,
and Steve hill dips his pots and then gets great effects by spraying glaze in
layers.
ceramics monthly has had great articles on him check out the years 85-87 and
you will find a great article on him
ruggles and rankin also once fire
thanks
Donn Buchfinck
San Francisco
Jeri Palmer on wed 7 jul 99
Thanks for the in put Don. I just opened my very first single fire and it
was great. (porcelain ^10, Ox) Everything was gorgeous. No warpage at all,
I work pretty big and very thin, so I always expect some but there was none.
I sprayed all the glazes and candled for about 5 hrs, It has been hotter than
the inside of a cow and I knew those pots had absorbed a lot of moisture. I
am just thrilled now I am asking all of you for your feelings I you have
tried both single fire and bisque which do you prefer and why? Also, if any
of you have any drop dead, knock your socks off glazes for a ^10 porcelain
you could pass them along. :)))) Thanks Jeri
Julia M. Townsend on fri 9 jul 99
Jeri,
I once fire for 2 simple reasons... COST & TIME. It costs me at least $15.00
every time I fire my kiln, and since I am doing slab work, and my kiln is 29"
deep, its very full when I fire, and it takes all of 12-14 hours to fire and
about 28-30 to cool down... mostly shelves in that thing!!! And I only load it
3/4's full as that is all the shelves I have.
I live in a townhouse, and can't do much else when I fire my kiln. So for me,
its the only cost effective way for me to do the slab work I am doing.
Julie in Michigan, where we finally have a reprieve from that heat wave....
Jeri Palmer wrote:
> ----------------------------Original message----------------------------
> Thanks for the in put Don. I just opened my very first single fire and it
> was great. (porcelain ^10, Ox) Everything was gorgeous. No warpage at all,
> I work pretty big and very thin, so I always expect some but there was none.
> I sprayed all the glazes and candled for about 5 hrs, It has been hotter than
> the inside of a cow and I knew those pots had absorbed a lot of moisture. I
> am just thrilled now I am asking all of you for your feelings I you have
> tried both single fire and bisque which do you prefer and why? Also, if any
> of you have any drop dead, knock your socks off glazes for a ^10 porcelain
> you could pass them along. :)))) Thanks Jeri
martin howard on wed 8 mar 00
Are there many out there who only fire once?
I have started to have a go at it, as it seems logical to save on fuel when
possible.
But, I have tried with it first with several quite good jugs. Slipped the
inside at leather stage. Waited a few days, but not until really bone dry,
and then glazed the inside.
A few moments later all three vessels had cracked into shards, soft
shards:-((
Well, should one always wait until they are bone dry?
Or is there a way of adapting a glaze to fit a little damper pot?
I know some single firers glaze at even leather stage. Does the glaze have
to be more like a slip, with more clay than usual?
Mine all have about 10 percent fine clay (my cat litter stuff). Perhaps that
is not enough.
Any ideas friends?
Martin Howard
Webb's Cottage Pottery
Woolpits Road
Great Saling
BRAINTREE
Essex CM7 5DZ
01371 850 423
martin@webbscottage.co.uk
www.webbscottage.co.uk Should be ready for 2000 :-) or 2001
ferenc jakab on wed 8 mar 00
Martin,
I refer you to a book written by an English potter Fran Tristram who has
written a book "Single Firing. Pros and Cons". It is an excellent starting
point. I glaze at leather hard, dip outside first and then inside when the
outside has touch dried but the pot is still leather green. And yes once
fired glazes need more clay than bisque glazes. A trick I was taught is to
add a small amount of the clay you pots are made of, 2%-3%.
No doubt you will get replies from those more knowledgeable than me.
Good Luck!
Feri
Stephani Stephenson on thu 9 mar 00
Martin
Years ago, at the university, there was one person who single fired,
and he made the whole process sound very mysterious and tricky. I've
found it to be just the opposite.
Here at Alchemie Studio we once fire our ram pressed tile, basins, and
architectural ceramics . as well as pots and sculpture.
We use many of the same glazes that are used on bisque ware. Main
difference is , the glazes are mixed with less water, (i.e.slightly
thicker consistency ), than glazes applied to bisque . We spray , pour
apply with brush, and even dip , depending on the piece. Some glazes
have a clay content of 15-20 % but others have very little clay. We
have very few problems with fit.
Also the ware is pretty substantial, not fragile or thin. I wonder
if your problem pieces were very thin walled?
We glaze when pieces are bone dry. When work is bone dry, it absorbs
the moisture from the glaze rapidly .This seems to ensure a nice even
application. Occasionally we glaze ware that is leather hard , but have
found that if the ware itself contains too much water, the wet glaze
tends to simply run over the surface without absorption or adhesion.
To clean off the drips, we use a wet piece of shag carpet (nailed to a
board) .As pieces are loaded into the kiln, we dragtheir bottoms over
the shag carpet (ouch!). water absorption is minimal, and its a good
way to clean off excess glaze without a lot of fuss or extra handling.
I've read very little about once firing, but the above process works
well for the ole Alchemists.
sincerely
Stephani Stephenson
mudmistress@earthlink.net
Alchemie Studio
Leucadia CA
Richard Gilbert on thu 9 mar 00
Hello Martin:
Allow me to suggest a clear glaze from Michael Cardew as a starting
point.
Potash feldspar 33.75
Quartz 27.50
Limestone 21.25
Ball clay 17.50
The key is the 17.50% plastic material. A single fire glaze needs to
shrink with the clay body as it dries. Most of my single fire glazes
contain 20% clay with a few containing 60% clay. The addition of 2%
Borax helps harden the glaze surface. I suggest glazing the inside of
pots first because the glaze coat is fragile and it's easier to judge
the dryness for the outside application. The actual state of dryness for
glazing is critical. I recommend glazing at the black hard state. The
clay should still be a dark color and cool to the touch but if you press
a fingernail into the surface, there is resistance. After you glaze the
inside wait until the pot returns to black hard and glaze the outside.
Look for problems where the two glaze coats overlap.
Once firing has a demanding schedule that revolves around drying.
Plastic draped around drying areas helps keep handles form getting dry
before the body of a pot.
Keep us informed of your progress.
Richard Gilbert
Cherryville, North Carolina
Bill Campbell on fri 10 mar 00
Martin
I singlefire nearly all of my pots. I have been doing it for 15 years or
more. I fire several hundred pieces a day. The body is porcelain. I line all
of the closed forms by pouring and spray the outsides of the pots when they
are bone dry. I even do crystalline gazes this way. As long as you are
careful to make sure that there is no dust left on the pot you should have no
problem. Make sure you let the pots sit long enough to have all of the water
evaporate before you put them in the kiln.
Handling is going to be slightly more difficult and you may want to continue
to bisk the more complicated shapes like teapots.
Eliminating that step is a real time and fuel saver. You can also double the
capacity of your kiln. It is worth the pain that you go thru to learn to do
it.
Good luck.
Bill
Jean Todd on fri 10 mar 00
I used to fire once. Like you I did it when fully dry (when leather hard
some bits are dryer than others) and I always dipped the whole pot into the
glaze very quickly. Never use tongs and always use both hands and all
fingers to support the pot.. Then hold the pot upside down to drain for some
time. But the main trick is to have the glaze thinner than normal. If the
glaze is of normal thickness it soaks into the pot more in some places than
others, putting stress onto some areas which then split. If the glaze is not
thick enough on the pot then you have to wait until the pot is fully dry
again before a second coat of glaze. Since I like thick lustrous glazes now
I have been bisqing for some time. However if you like a glaze that only
needs to be thin it is the way to go. Tip....if doing teapots before
attaching the spout get the pot ready and put the holes for tealeaf drainage
in and then apply a little wax to the holes, then attach the spout. This way
you have no trouble with glaze filling the holes. I found glazing this way
most glazes worked well providing they had some clay in them. No need for
lots of clay which you seem to need when glazing leather hard stage.
Jean
"Lang may your lum reek"
Jean Cochran on fri 10 mar 00
Dear Martin:
I single fired for several years. Finally, I got sick and tired of losing
pieces and time. When one glazes over bisque, it goes quite quickly. When I
was single firing, I glazed exclusively by spraying on the glazes. I sprayed
two to three coats and found that I had to be very careful after the first coat,
to not get too much moisture over the previous coat or I would get little
bubbles. It can surely be done, I just think my time is worth more than the
savings in fuel.
Good luck,
Jean Cochran
Fox Hollow Pottery
New Haven, Kentucky
martin howard wrote:
> ----------------------------Original message----------------------------
> Are there many out there who only fire once?
> I have started to have a go at it, as it seems logical to save on fuel when
> possible.
>
> But, I have tried with it first with several quite good jugs. Slipped the
> inside at leather stage. Waited a few days, but not until really bone dry,
> and then glazed the inside.
>
> A few moments later all three vessels had cracked into shards, soft
> shards:-((
>
> Well, should one always wait until they are bone dry?
> Or is there a way of adapting a glaze to fit a little damper pot?
> I know some single firers glaze at even leather stage. Does the glaze have
> to be more like a slip, with more clay than usual?
> Mine all have about 10 percent fine clay (my cat litter stuff). Perhaps that
> is not enough.
>
> Any ideas friends?
>
> Martin Howard
> Webb's Cottage Pottery
> Woolpits Road
> Great Saling
> BRAINTREE
> Essex CM7 5DZ
> 01371 850 423
> martin@webbscottage.co.uk
> www.webbscottage.co.uk Should be ready for 2000 :-) or 2001
Mike Obrien on sat 11 mar 00
For Jean and anyone who doesn't spray because of bubbles after the first
coat. Add CMC or even better Vee Gum CER. I use 2 tablespoons per 2500
grams of dry glaze. I spray 5 coats in 3 minutes, no bubbles, however your
body must be thick enough to absorb the water. I've been spraying 5 gallons
a day for 20 years. It works.
Mike O'Brien
Steve McNutt on sun 12 mar 00
I have been once firing some of my pieces for a while. One "hint" I read
somewhere was to wipe the side you are not glazing with a moist sponge. This
helps to equalize the moisture when you glaze the "inside". I also use a big
painter's brush and slop the glaze on rather than pour or dip some things.
This is largely due to the fact that I am generally slow and uncoordinated.
Interestingly, I found I could use nearly all my glazes without modification
on bone dry pieces and can brush or spray them on wet or dry without apparent
differences. I make a lot of teapots and can't pour glaze them unless they
have been bisqued. If the day ever comes I can do this I will consider I
have made some kind of conquest. I did some comparisons of identical pieces
bisqued/raw glazed and really couldn't tell the difference. I think there
is a subtle difference in the "feeling" of the pots but can't prove it even
to myself. There is the directness of it. By the time a piece has been
through a bisque firing and sits on the shelf for a few weeks, I have lost
relationship with it. I just dread the glazing decisions then. When I carry
a series of pieces all the way through from forming to finishing without that
time lapse, I enjoy them much more.
I am in Pennsylvania this week. We have been flirting with Spring. Hope I
get out before the late snow.
Mary Beth Bishop
Martin Howard on fri 1 sep 00
Have other single firers found that the glazes they used on bisque are not
so strong when used on the leather hard clay for once firing?
I wonder if there is a logical reason for this?
I tend to polish the surface of my leather hard pots with the potters thumb.
Does the bisqe firing open the surface up and so let the pot absorb more
glaze, while the dried greenware is setting up a barrier to absorbing so
much glaze because it still has some water content?
Or is there some other answer?
Martin Howard
Webb's Cottage Pottery
Woolpits Road, Great Saling
BRAINTREE, Essex CM7 5DZ
England
martin@webbscottage.co.uk
DEBBYGrant@AOL.COM on fri 1 sep 00
Dear Martin,
Your glaze should be somewhat thicker for once fired because the greenware
will soak up the water more readily than bisque. I would also consider it a
waste of time to polish the pots with the potter's thumb as this could very
likely repel the glaze and is not necessary anyway. I do both once firing
and bisque glazing and have never noticed a difference in the strength of
the glaze.
Good luck,
Debby Grant in NH
Stephani Stephenson on fri 1 sep 00
Martin Howard wrote:
Have other single firers found that the glazes they used on bisque are
not
so strong when used on the leather hard clay for once firing?
I tend to polish the surface of my leather hard pots with the potters
thumb.
Does the bisqe firing open the surface up and so let the pot absorb more
glaze, while the dried greenware is setting up a barrier to absorbing so
much glaze because it still has some water content?
Martin
When once firing, I always apply glaze to BONE dry greenware, not
LEATHER hard greenware.
It makes a great difference .
Are you polishing pots because you leave some of the surface unglazed
and want a polished look on unglazed areas? Otherwise not sure if
polishing is necessary in fact may be counterproductive, if glazing over
unfired surface.
Stephani Stephenson
Leucadia CA
http://home.earthlink.net/~mudmistress/
http://www.alchemiestudio.com
ferenc jakab on sat 2 sep 00
> Have other single firers found that the glazes they used on bisque are not
> so strong when used on the leather hard clay for once firing?
>
> I wonder if there is a logical reason for this?
>
> I tend to polish the surface of my leather hard pots with the potters
thumb.
> Does the bisqe firing open the surface up and so let the pot absorb more
> glaze, while the dried greenware is setting up a barrier to absorbing so
> much glaze because it still has some water content?
Martin,
What do you mean by not as strong? Certainly polishing the green ware would
close the pore or surface openings in the clay body, and I have found that
glaze was reluctant to adhere to some of my sculptures which I had
semi-burnished with a leather kidney I make for this purpose.
I'm reluctant to ask whether you have enough clay in your glaze. I'm sure
you are experienced at formulating such glazes. But that, in my experience
is the chief reason for glazes not adhering to raw clay.
Feri.
Paul Taylor on sat 2 sep 00
Dear Martin
I would agree with you.
I used to put it down to glazing some of the pot before it was fully dry .
My glazes had only ten percent clay they did not shrink much. So the body
shrank away from the glaze. But since the pot was so much stronger before it
was fully dry I put up with it. Just being more careful with the rims when I
put things in the kiln
I decided that glazing a powdery dry surface was not the best and
tended to act as a barrier stopping the glaze adhering to the pot so over
sponging the pot was a bad idea and contrary wise bernishing (polishing the
serface) did not help either. The glaze did not peritrate the body - not
getting any "Key".
One of the best tricks I learnt was not to glaze the inside and the
outside at the same time and if in doubt glaze the out side first.
I raw glazed every thing. I stopped because I loose no pots in the glazing
process when I biscuit, and two short firings are better on my nerves than
one long one .
I miss raw glazing. the imediacy ! and cleaning up biscuit puts your
teeth on edge.
-- Regards Paul Taylor.
Westport Pottery, Liscarney, County Mayo. Ireland.
http://www.anu.ie/westportpottery/
> From: Martin Howard
> Reply-To: Ceramic Arts Discussion List
> Date: Fri, 1 Sep 2000 20:36:27 +0100
> To: CLAYART@LSV.CERAMICS.ORG
> Subject: Once firing
>
> Have other single firers found that the glazes they used on bisque are not
> so strong when used on the leather hard clay for once firing?
>
> I wonder if there is a logical reason for this?
>
> I tend to polish the surface of my leather hard pots with the potters thumb.
> Does the bisqe firing open the surface up and so let the pot absorb more
> glaze, while the dried greenware is setting up a barrier to absorbing so
> much glaze because it still has some water content?
>
> Or is there some other answer?
>
> Martin Howard
> Webb's Cottage Pottery
> Woolpits Road, Great Saling
> BRAINTREE, Essex CM7 5DZ
> England
> martin@webbscottage.co.uk
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
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>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
Khaimraj Seepersad on sat 2 sep 00
Good Day to All ,
Martin , you may find this useful -
A Clay Glaze .
3.3 Na20 940 deg.c
5.5 K20
2.4 Mg0
1.6 Ca0
2.1 Sr0 [ was 2.0 Ba0 ]
19.3 B203
15.1 Al203
50.8 Si02
[ source W.Steger . Ber deut keram Ges
1927 ---- Ceramic Glazes - D.C.Maynard
--- Borax Holdings Ltd. ]
** Please have this glaze tested for
B203 release , there is a goodly
amount .
I use this glaze on the outside , beyond
lip contact , on functional wares [ vitreous
body ] .
There is a good deal of leeway here ,
the Na20 can interchange with the
K20 , or you leave out the K20 for
all Na20 .
All Ca0 [ no Mg0 , or Sr0 ] will frost the
glaze .
Can also be no alkalines , more Si02 .
I use a 23.5 Al203 / 65 % / 2.5 other .
Clay at 65 % clay - 35 % frit .
Works very well on my 60 % Earthenware
clay --- 40 % Frit / self grog / Feldspar
bodies .
Stay well ,
Khaimraj
-----Original Message-----
From: DEBBYGrant@AOL.COM
To: CLAYART@LSV.CERAMICS.ORG
Date: 01 September 2000 15:44
Subject: Re: Once firing
>Dear Martin,
>
>Your glaze should be somewhat thicker for once fired because the greenware
>will soak up the water more readily than bisque.
- snip -
I do both once firing
>and bisque glazing and have never noticed a difference in the strength of
>the glaze.
>
>Good luck,
>
>Debby Grant in NH
vince pitelka on sat 2 sep 00
> Your glaze should be somewhat thicker for once fired because the greenware
> will soak up the water more readily than bisque. I would also consider it
a
> waste of time to polish the pots with the potter's thumb as this could
very
> likely repel the glaze and is not necessary anyway.
Sorry to be so contrary, but the first statement is incorrect, although the
second certainly is correct. The glaze needs to be thicker because the
greenware will NOT soak up water as readily as bisque. It is like applying
glaze to a partially vitrified pot - the glaze must be thicker, and/or must
have some sort of gum medium added.
- 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/
Jim Bozeman on sat 2 sep 00
Martin, I studied with Dennis Parks in Nevada and all he does is once fire.
He told me to be successful you have to have a bit more clay in the glaze
recipe. When glazing plates, he poured the glaze over the plate face and
then wiped the back of the plate with a sponge. He said it was to equalize
the face and the back of the plate. I still have work from when I was out
there. A wonderful guy to study with. Jim Bozeman
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Priscilla Wilson and/or Janice Lymburner on sun 3 sep 00
Hi - I've been once firing and using two coats of clear or three coats =
of colors - Amaco's Sahara Cone 6 glazes on bone dry pots. (I'm not =
ready to start making my own glazes yet!) It works great - no problem =
whatsoever. Priscilla
Martin Howard on sun 3 sep 00
Ferenc asks:- What do you mean by not as strong?
Well, the colour is a tone less and it looks as if I dipped the ware for
only half the time I dipped the bisqued ware. So the red clay below shows
more than intended.
I have ten percent clay in these glazes and there is no problem with the
glaze falling off, peeling etc.
>From what you all say, it seems that I should leave the ware until bone dry,
instead of glaze at leatherhard. Or glaze the inside at leather and the
outside at bone-dry. Or visa versa. And do not burnish those parts which I
intend to glaze.
It is all such a lovely learning process and I am gathering a goodly pile of
shards for the base of a new patio.
Thanks everyone.
Martin Howard
Webb's Cottage Pottery
Woolpits Road, Great Saling
BRAINTREE, Essex CM7 5DZ
England
martin@webbscottage.co.uk
ferenc jakab on mon 4 sep 00
----- Original Message -----
From: "Martin Howard"
To:
Sent: Sunday, 3 September 2000 5:10 pm
Subject: Re: Once firing
> Ferenc asks:- What do you mean by not as strong?
>
> Well, the colour is a tone less and it looks as if I dipped the ware for
> only half the time I dipped the bisqued ware. So the red clay below shows
> more than intended.
Martin,
If ten percent works for you then that is fine. I'm happier at 15-20% but I
fire to a high "maijolica", ^2. I dip/paint/spray at leather hard and at
first I had a similar problem with the glaze looking thin.
Because at leather hard the water is not absorbed as quickly as on dry or
bisque ware, the glaze looks thick sitting on the ware but actually not as
much glaze has collected as on dry or bisque forms. It looks thicker because
it is still "padded out" by water. The answer for me was to a) dip for
longer, or b) to add a second or third coat. choosing the moment for
recoating with brushing is tricky. You have to catch the glaze before it
gets so dry it brushes off but dry enough not to run off from the water in
the fresh glaze. (I.e. it absorbs the water from the fresh aplication.)
I mix my glazes to a thick cream texture. I'm not scientific enough to use a
hydrometer. Besides the ingredients in the glaze dictate the amount of water
required. For instance Ferro Frit 3124 has a peculiar effect in a glaze and
I find a high frit glaze needs less water than a high clay glaze.
Hope some of this makes sense.
Feri
Joyce Lee on sun 10 sep 00
I decided to try at least one small pot as a once-fire in a regular load
of bisqued&glazed pots. I fired two small bowls ... one bisqued, one
not..... both glazed with David's Matt Tallow on brown clay .... fired
to ^11 gas reduction. After firing, they look the same; no problem. I'll
try a couple more next time, a mite larger, with another glaze.
Joyce
In the Mojave
Martin Howard on mon 11 sep 00
Joyce, when test firing your bowls, did you glaze at leather or bone? There
seems to be a basic difference, because of the amount of water still in the
pot and its reluctance to take in any more.
But at bone, I found myself being rather timid about differential cracking.
It seems to be a test of one's throwing. All the pot should be of the same
thickness, else it cracks, just because of the extra amount of water being
suddenly taken in.
Martin Howard
Webb's Cottage Pottery
Woolpits Road, Great Saling
BRAINTREE, Essex CM7 5DZ
England
martin@webbscottage.co.uk
WHC228@AOL.COM on tue 12 sep 00
Joyce
I have been once firing my pots for about 15 years. I glaze them bone dry and
wait at least a day after they are glazed to fire them, so that the water has
time to evaporate. I put a penny on the ware boards to keep track of which
day they were glazed. I never a pot to that.
Single firing certainly has its advantages. Not having to fill and unload a
kiln, tying up a kiln while you bisk, and of course the energy to fire that
extra kiln.
You will have to go through the pain of learning how to do it, but it is
worth it.
I even do it with my crystalline glazed porcelain with no problems.
I do bisk some of the more complicated shapes, because they are less risky to
handle when bisked.
Bill Campbell
PS with the rising cost of energy it is a good time to look at single firing.
Martin Howard on mon 12 aug 02
Here is an answer to the recent question by Valerie Johnson from the
acknowledged expert on Once Firing in the UK.
discipline of single firing, but like every constraint you put upon your
working approach, you may need to give new consideration to other aspects
usually taken for granted.
In my book 'Single Firing: the Pros and Cons' I cover most basic approaches,
and a great deal of anecdotal material from the direct experience of fellow
single firers. Just as with twice firing, experience and work are as
individual as the makers.
On the whole, the early stage of a single firing need go no slower than the
early stage of a bisc firing - I make sure that I take about a couple of
hours to reach 100oC, but after that I whack it up like any other glost I
fire from cold to cone 10 in 8-12 hours (depending on variables such as
density of pack, weather, my other activities through the day etc). Often,
however, I will find myself packing the kiln in the wee small hours (pushing
deadlines to the limit - don't we all?!), so may then pre-heat it overnight
on a low flame, thus making the active firing time sometimes as little as
6-7 hours.
My materials are not highly carbon-bearing, so I don't hover around for a
slow carbon burn out, but if you have a highly plastic or carbon rich body
you may want to take as much as a couple of hours between 700 and 900o. An
open body doesn't usually present too much difficulty as the carbon can
continue to escape through the pores of the clay well into the firing.
Trial and error are, as always, the best ways to get to know how your own
materials perform under any new set of circumstances.
Some makers argue that there is a greater depth imparted to the glaze by
single firing because of 'the prolonged firing' - I cannot really support
that, as the firing is not necessarily significantly prolonged for single
firing purposes, and if it is, it would be so early in the firing that any
difference in effect on the actual maturation of the glaze would be minimal,
and almost certainly not measurable. Others say that the application of the
glaze to the raw body increases the clay-glaze interface, and that that is a
cause of greater depth. I remain sceptical of any great aesthetic benefit
or disbenefit - I single fire for practical rather than aesthetic reasons
... Why would anyone deliberately go upstairs twice to fetch one pair of
socks?
So much for firing. It's a very long time (about 12 years I think) since I
bisc fired anything, so I don't recall from personal experience how take up
of the same glaze on the same body unfired would compare. A lot will depend
on the make-up of the glaze and body, and on whether you are glazing at dry
or leather. The method of glaze application will also affect take up - if
you are hesitant in the handling of the pieces, it may be that you are also
being hesitant in the glazing.
If you look at some of the finest of the ancient Chinese wares, the glaze is
in some cases noticeably thicker than the body, and there is much evidence
to indicate that these pieces were glazed in the raw state and single fired.
If you are glazing pots in the dry state you may be ok using the same glaze
as you normally use on bisc. If in the leather state, you will need more
clay to help the glaze to fit the body as they dry together, with the
consequent adjustments to balance the fired glaze effect.
To increase thickness of the glaze when pouring onto dry ware, I usually
pour a second coat immediately after the first coat of glaze has lost its
shine. If you let the glaze go white dry before applying a second coat, the
rewetting may lift and blister the glaze. Sprayed glazes can be easily
built up in layers, but again, don't allow a first coat to dry to much
before wetting with a second. If you need to allow a time lapse between
coats, make sure the first coat is richer in clay and is thicker on the hand
than the second. Sponging and brushing usually lend themselves well to a
build up of layers too.
I hope that this is a help - otherwise, I refer you to my book (mentioned
above - published by Gentle Breeze in the US).
Best wishes
Fran Tristram>
I forwarded the posting to Fran as I knew she would be able to help in this
matter.
Martin Howard
Webbs Cottage Pottery
Woolpits Road, Great Saling
BRAINTREE, Essex CM7 5DZ
01371 850 423
martin@webbscottage.co.uk
http://www.webbscottage.co.uk
Updated 6th July 2002
om on sun 2 sep 07
At 12:58 -0700 on 9/2/07, Dennis McAvoy wrote:
> Hi. I am moving in the direction of once firing my pottery to cone
> 10. I presently bisque first. Are there any pitfalls that I should
> be aware of before I make the leap? Dennis
Another topic at which I'm no expert but have an opinion. ;-)
Everything I fire in my anagama and raku kilns is once fired. The
real trick is to go slow. I usually have something in the anagama at
the latter stages of leather hard -- my preheat is two days long
though. The raku once fire isn't bad either and much faster -- only
5 or six hours perhaps. And it works fine:
http://www.anagama-west.com/firing_log/archives/80 (not cone 10 but
I hit 2200 F with a few sticks of wood, dug up clay test, pottery was
leather hard when firing started).
http://www.anagama-west.com/firing_log/archives/17 (what happens
when you push too fast in a quasi hole/paper kiln - great fire)
http://www.anagama-west.com/firing_log/archives/22 (glazed raku,
first try at once fire raku, broken foot, began the firing in hot
kiln -- much better to start off in a cold kiln)
Anyway, if raku can be once fired, there's no reason you can't fire
once in a conventional kiln. People have made lovely work in once
fire kilns for thousands of years. Certainly there will be much to
learn but it isn't like genetic engineering or something like that.
If people used to do it without the benefit of the internet,
literacy, accumulated knowledge, etc, there's no reason you can't. A
little fire, fun and experimentation should be a wonderful experience
because, realistically, what's the worst thing that happens? You
lose a kiln load. When you consider that clay is about the most
abundant natural resource on the planet, well, it's nothing to cry
about (obviously when you experiment, you'll be making test pieces in
which you have not invested inordinate amounts of time).
Sounds to me like you're in for some great times experimenting. And
do push it till you get things exploding. What's life without a few
pops?
http://www.youtube.com/watch?v=JQO-wWDib3M
Odin
Dennis McAvoy on sun 2 sep 07
Hi. I am moving in the direction of once firing my pottery to cone 10. I presently bisque first. Are there any pitfalls that I should be aware of before I make the leap? Dennis
Maurice Weitman on sun 2 sep 07
At 12:58 -0700 on 9/2/07, Dennis McAvoy wrote:
>Hi. I am moving in the direction of once firing my pottery to cone
>10. I presently bisque first. Are there any pitfalls that I should
>be aware of before I make the leap? Dennis
In a word: Yes. My opinion follows.
You should read the several books available. among the best resources
and easiest to find is by Fran Tristram- "Single Firing,The pros and
cons" ISBN 0713639024
You should join the other mailing list dedicated to single firing:
You should search the clayart archives (which seem to work only 10%
of the time lately -- and it's not working as I write this. In fact,
the ceramics.org -- ACerS site is not responding at all -- I'm
shocked!!!)
You should therefore search the version of the clayart archives on potters.org:
That will return over 300 "threads" where single firing was
mentioned. You may also search for "once fired"
"single fire" etc. (A "thread" is a set of messages where posters
didn't change the subject header. But others seem to take delight in
changing the subject header... they're lazy or they think it's cute,
which I believe is rude and counterproductive. But THEY don't give a
damn. I feel better now, how was that for you?)
Also search in google.
You should make sure your pots are of even thickness.
You should experiment with glazing when bone dry and green; they each
have their benefits and problems.
You should be careful to not soak your dry pots with glaze and/or
glaze inside and outside unevenly... the pot may delaminate and melt
before your eyes.
You should experiment with your existing glazes. You might need to
add some bentonite. You will certainly have to adjust for the
absence of good absorption that comes with bisqued pots.
You should fire pots only when really, really dry.
You should generally fire up to bisque temperature as though you were
bisque firing.
You should look for magazine articles; Steven Hill has three or four
published. Again, check the web.
You should, in other words, do shitloads of research and
experimenting using your own clay bodies, glazes, and kilns.
It's not rocket science, but bears a thoughtful approach and I
believe it will be worth the effort.
Perhaps others will be willing to give you more info, but I encourage
you to do the research and experiment.
And I mean that sincerely.
Regards,
Maurice
Terrance Lazaroff on mon 3 sep 07
Dennis;
Maurice has given you a good list to look at when considering mono firing.
I feel the point about the glaze application to be pivot able. Once the
proper glaze is found the firing can take place just like any bisque firing
with the temps being raised as a normal firing at red heat. The method of
glazing will require the greatest effort in order to meet your
expectations. When I watched the glazers working in Sanbao they glazed the
interior first and then let the pot dry over night. They then glazed the
outside of the piece. They used a suction cup device that held the bowl
from the inside allowing to dip the outside of the bowl into the glaze up
to the rim. They waited another day to refine the trimming of the foot
enable the insertion of the kiln stilt, a small clay pellet. They then
cleaned the rim of the bowl and glazed it to finish the process.
Large pieces were glazed interior first then spray glazed to finish.
Most of the porcelain in Jingdezhen is single fired.
You can see what the stilt looks like by going
to:http://www.clayart.ca/00400Ming_Style_Pottery.htm
Terrance
Paul Haigh on tue 4 sep 07
I'm still putting the touches on my wood kiln (1/2 the chimney and a kiln shed), but will be once firing. I did a wood fire this spring and just made up some ash containing glazes with 5% bentonite, little attention to thickness, and dipped (tenmoku, nuka). They worked out great. The guy that ran the firing placed the once-fired pots where they wouldn't cause much damage if they blew, and took the firing slow to bisque temps.
Russel Fouts on tue 4 sep 07
The British Ceramics magazine, Ceramics Review has a great article on
once firing.
We did it back in the late 70's in a college studio environment.
We glazed leather hard by dipping. Grab a cup, bowl or pitcher by the
foot, dip it upside down into the glaze, 'POP' it, swirl it and take it out.
I never thought it was a big deal until I heard it discussed here on
Clayart. It was just one of the ways we worked.
Russel
Russel Fouts
Mes Potes & Mes Pots
Brussels, Belgium
Tel: +32 2 223 02 75
Mobile: +32 476 55 38 75
Http://www.mypots.com
Home of "The Potters Portal"
Over 3000 Pottery Related Links!
Updated frequently
"The enumeration in the Constitution of certain rights
shall not be construed to deny or disparage others
retained by the people"
9th Amendment to the Constitution of the United States of America
moira clinch on thu 6 sep 07
For many years I have made containers for flowers, often large
slab-built shallow dishes. For economy of time and fuel I have
successfully raw-glazed these at the bone dry stage. I applied the
glazes (not always adapted specifically for once-firing) by spray
glazing. I bought a second-hand compressor over thirty years ago, and
it is still going strong. Often needing a quick turn around of work, I
have never worried too much about further drying after the glaze
application, just checked for a clean base with a damp sponge. The other
advantages of spray glazing are that I can cover a large area of clay
surface without dribbles and finger marks, as well as overlaying
contrasting glazes for toning and shading. The only cracks that may
occur were if I applied glazes too thickly - or made a badly constructed
pot in the first place! English potter, Fran Trtistram has written a
book - Single Firing- the pros and cons. (Ceramic Handbooks range by A&C
Black, London and Gentle Breeze, Florida)
Moira Clinch
Russel Fouts wrote:
> The British Ceramics magazine, Ceramics Review has a great article on
> once firing.
>
> We did it back in the late 70's in a college studio environment.
>
> We glazed leather hard by dipping. Grab a cup, bowl or pitcher by the
> foot, dip it upside down into the glaze, 'POP' it, swirl it and take
> it out.
>
> I never thought it was a big deal until I heard it discussed here on
> Clayart. It was just one of the ways we worked.
>
> Russel
>
>
>
> Russel Fouts
> Mes Potes & Mes Pots
> Brussels, Belgium
> Tel: +32 2 223 02 75
> Mobile: +32 476 55 38 75
>
> Http://www.mypots.com
> Home of "The Potters Portal"
> Over 3000 Pottery Related Links!
> Updated frequently
>
> "The enumeration in the Constitution of certain rights
> shall not be construed to deny or disparage others
> retained by the people"
>
> 9th Amendment to the Constitution of the United States of America
>
> ______________________________________________________________________________
>
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>
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>
Lee Love on thu 6 sep 07
On 9/6/07, moira clinch wrote:
> For many years I have made containers for flowers, often large
> slab-built shallow dishes. For economy of time and fuel I have
> successfully raw-glazed these at the bone dry stage.
Tight clay bodies can be raw fired, but open ones just crack and
crumble. Open clay bodies need to be glazed at leather hard.
I glaze the inside of co-shigaraki tea bowls at leather hard.
--
Lee in Minneapolis, Minnesota USA
"Making pots should not be a struggle.
It should be like walking down a hill
in a gentle breeze." --Shoji Hamada
http://mashikopots.blogspot.com/
"For a democracy of excellence, the goal is not to reduce things to a
common denominator but to raise things to a shared worth."
--Paolo Soleri
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