Joseph Herbert on tue 14 mar 00
Of course the dinnerware industry is the champion at refiring since they
bisque at the highest temperature and fire at successively lower
temperatures as decoration is added. The last firing might be cone 022
for the gold leaf or luster. I don't know for sure but it would not
surprise me to find that some patterns of dinnerware are fired 10 or 12
times to get all the decoration on.
For us less ambitious types that would like just one second chance, I
believe the issue is crystobalite formation in the claybody. Some
bodies, those containing free silica and other crystobalite promoting
materials, will develop a significant amount of this high temperature
phase of quartz upon the first firing. If one makes through the first
inversion upon cooling after the first firing, the second firing
requires making it through the inversion on the way up to temperature
and again on the way down - but probably with more crystobalite than
before. A couple of cycles of this kind of pattern almost assures a
broken pot.
IT is obvious, from industry practice, that it is possible to control
this lurking pot breaker. However, it cannot be easy for us, especially
if we purchase a clay body compounded by others. Crystobalite control
requires complete knowledge of the contents of the clay, something that
may be difficult to get from the corner clay mixing store.
Remember, you should never love your pots too soon.
Joseph Herbert
peachblow pottery on sun 4 mar 01
My first post. David Hendley mentioned "striking", but it does not =
require reduction. Glass blowers use the process all the time for Ruby =
Reds. It's a process of simply reheating the glass, or pot, and the =
copper repositions it's nuclear structure and it goes RED. It's amazing =
to watch a glass blower do it, but you can put a not so red piece in a =
cone 06 firing and the red will many times go redder. It all depends =
where the copper is to begin with, over-reduced, under-reduced, or =
whatever. I've done it many times, try it. Tom Turner
Earl Brunner on mon 18 mar 02
I've had a refired cone 10 piece blow up on me. It was a mug that had been sitting
around for awhile and apparently had been out in the rain and had absorbed some
moisture. It blew into the tiniest pieces, all over everything in the kiln.
John Jensen wrote:
> I don't refire much, but have had the experience of having a refired cone
> six piece blow up on me. I had assumed (dangerous) that the vitreous ware
> would not have moisture in it, but apparantly it is tough for that moisture
> which does get in there to get out again in a hurry. So if you are refiring
> a piece which has had a chance to absorb any moisture (and maybe glazing in
> and of itself is enough of a chance) I'd try firing very slowly, at least
> in the lower ranges.
> John Jensen, Mudbug Pottery, Annapolis
> mudbug@toad.net, www.Toadhouse.com
>
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--
Earl Brunner
http://coyote.accessnv.com/bruec
mailto:bruec@anv.net
Reb j geary on mon 18 mar 02
Has anyone had any experience refiring a high fired stoneware? I had a
piece that I was not happy with the glaze and would like to change it.
~Rebecca
Jan Goodland Metz on mon 18 mar 02
I've only done it twice and it worked both times. I place the peices in an
electric kiln and warmed them up really hot actually until i needed hot pad
holders to pick them up and then dipped them in the glaze and wood fired them
again to cone 12, they turned out nice. But I was using the same glaze on them
agian.
Jan
Reb j geary wrote:
> Has anyone had any experience refiring a high fired stoneware? I had a
> piece that I was not happy with the glaze and would like to change it.
> ~Rebecca
>
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John Jensen on mon 18 mar 02
I don't refire much, but have had the experience of having a refired cone
six piece blow up on me. I had assumed (dangerous) that the vitreous ware
would not have moisture in it, but apparantly it is tough for that moisture
which does get in there to get out again in a hurry. So if you are refiring
a piece which has had a chance to absorb any moisture (and maybe glazing in
and of itself is enough of a chance) I'd try firing very slowly, at least
in the lower ranges.
John Jensen, Mudbug Pottery, Annapolis
mudbug@toad.net, www.Toadhouse.com
Rikki Gill on mon 18 mar 02
I do it all the time with cone 10-11 porcelain, so I think it would work for
stoneware as well. It does crack sometimes, but I'd rather take the chance,
and the color is always better the second time. Rikki Gill
----- Original Message -----
From: "Reb j geary"
To:
Sent: Monday, March 18, 2002 7:43 AM
Subject: refiring
> Has anyone had any experience refiring a high fired stoneware? I had a
> piece that I was not happy with the glaze and would like to change it.
> ~Rebecca
>
>
____________________________________________________________________________
__
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
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>
> Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
>
Craig Martell on mon 18 mar 02
Hi:
There isn't a problem refiring anything as long as you proceed gently with
temp rise. The only pieces that could be problematic are ovenware and pots
that are subjected to quick temp changes such as teapots and mugs. When
bodies are fired past cone 6 and on up to the cone 10 range there's a
chance of developing some cristobalite. If your claybody is balanced and
has an adequate amount of feldspar the cristobalite will be taken into the
body glass and basically nullified. But it also develops on an ongoing
basis so with one firing you may get a bit of cristobalite and if you
refire you will develop more. I do know of instances where refired
ovenware has failed because of cristobalite develpment.
regards, Craig Martell in Oregon
Jeff Tsai on mon 18 mar 02
HI,
Craig is right on mostly, but I'd like to point out a minute chance that a
problem may occur. Since I didn't see the orginal post, I'll just assume
you're doing a rather generic refire. However, beware refiring a piece if the
original firing has a crazed glaze and you have let liquid sit in your piece
for any small period of time. Recently a friend of mine had a refired cone 10
piece bubble and bloat (the body) and even crack apart because he had used
the piece a couple times before and water had seeped into the claybody again.
The normal quick firing for glaze caused something to occur, likely steam, to
ruin the body. I think Craig is right on about controlling your temp. well.
-jeff
"Hi:
There isn't a problem refiring anything as long as you proceed gently with
temp rise. The only pieces that could be problematic are ovenware and pots
that are subjected to quick temp changes such as teapots and mugs. When
bodies are fired past cone 6 and on up to the cone 10 range there's a
chance of developing some cristobalite. If your claybody is balanced and
has an adequate amount of feldspar the cristobalite will be taken into the
body glass and basically nullified. But it also develops on an ongoing
basis so with one firing you may get a bit of cristobalite and if you
refire you will develop more. I do know of instances where refired
ovenware has failed because of cristobalite develpment.
regards, Craig Martell in Oregon
"
Paulette Carr on tue 19 mar 02
Rebecca,
I refire frequently ... cone 9 oxidation ... often 2 or 3 times. Sometimes,
when I don't like the surface, but believe that there is enough glaze on the
piece, I will just put it into the next glaze firing. The results are that
it is usually better, probably because the glaze did not come to maturity the
first time (this may be the case with a temmoku that I use and love). There
are many cases where I decide that I did not have enough glaze on the first
time, or want to add another layer of glaze. I should mention here, that I
apply my glazes by brushing. When reglazing already-glazed pieces, I first
brush them with a watered-down solution of Sobo glue (or Elmer's) and allow
that to dry before brushing on the new glaze. It may not be totally
necessary, but I feel that this provides a tooth for the first layer of new
glaze. I use a hair dryer to aid in drying the glaze before reapplying or
coating with a different glaze. I simply refire with my regular schedule for
glaze firing which is admittedly slow. I have never had a piece blow up, but
I have never poured water over or into the pieces that I intend to refire.
No guarantees, but is worth a try. It may work for me because my claybody
allows it. Just in case you are interested, the clay I use is vitreous at
cone 9. I try not to make my pieces so precious that loosing them will ruin
my life. I can always make another one ... even better the next time! Think
of what you learn in the process. Just in case, put these pieces on a
separate shelf.
Good luck!
Paulette Carr
Craig Martell on tue 19 mar 02
Hi:
Jeez, what a can of worms! The post that I sent yesterday didn't mention a
lot of stuff I thought you guys knew anyway. I just wanted to throw out
the idea of cristobalite development in refires of ovenware and other
thermally challenged pots.
Pots that have been fired to vitrification or near vitrification shouldn't
be refired if they've been used or exposed to moisture because, as John
Jensen said, they don't give up their moisture easily. The lattice is very
tight and the migration of water in and out of this tight lattice is a slow
trip.
Against my advice, a woman had me reglaze and refire a bowl that she'd
chipped. The chip wasn't all that ugly and I told her I could smooth it
down so she could use the bowl but she wanted it refired. After a good
cleaning, I placed the bowl by my woodstove for about a week and then
glazed it and refired to cone 10 with a bit of time added to the firing
until I'd passed the quartz inversion then the firing proceeded as
usual. The bowl came out fine but the glazes were a bit more fused and
moved slightly. She didn't like that although I'd warned her that this
would happen. Also, this was one of my pieces and not someone elses. My
stuff is cone 10 porcelain which refires fairly easily in terms of
moisture. Porcelain is tighter and more vitrified than stoneware so the
moisture thing isn't as bad. Porcelain also contains so much feldspar that
cristobalite is rare, even in a refire unless it's a badly formulated body.
Usually, if I'm going to refire anything, I do it right away in the next
fire. This happens very rarely as I usually trash bad seconds and rejects
and move on. You need to proceed with extreme caution if you attemp to
refire a much used piece or one that has been exposed to the elements. My
advice here is, don't do it!
Also, refired pots that bloat don't do this because of absorbed
moisture. If there is that much moisture present the pot is toast before
you even near the quartz inversion and you've added little bits of shard to
a lot of your other pieces. Pots that bloat in a refire do so from
outgassing thru a tight body that does not allow the exit of these
gasses. We ain't talking steam here. I haven't seen a pot bloat from
refiring but I do know that it happens. The body may be over fluxed and
you have to take this on a case by case basis. If you want to check out
the possibility of this happening before you refire, do an absorbtion test
to determine the vitrification and proceed from there. However, if you are
going to go to all this trouble, just make another pot and you'll probably
save a lot of time and have a good piece.
regards, Craig Martell in Oregon
Celia Littlecreek on tue 19 mar 02
Snip> Has anyone had any experience refiring a high fired stoneware?
I did that with an especially nice vase (pronounced VAAAZ because it was
spendy). The first time, the clay had pooled in big drips at the bottom. I
ground off the globs and refired. Now it is a VAAAZ, not a vase! :)
I also high fired some stoneware, it was gross. I brushed on some cone 04
glaze, a commercial crystal type, I think it was called alligator, and fired
again to 04. Turned out to be one of my favorites.
Judith Frederick on wed 20 mar 02
how did you get the glaze to adhere to the already glazed surface to refire
the piece?
>From: Celia Littlecreek
>Reply-To: Ceramic Arts Discussion List
>To: CLAYART@LSV.CERAMICS.ORG
>Subject: Re: refiring
>Date: Tue, 19 Mar 2002 16:43:53 -0600
>
> Snip> Has anyone had any experience refiring a high fired stoneware?
>
>
>I did that with an especially nice vase (pronounced VAAAZ because it was
>spendy). The first time, the clay had pooled in big drips at the bottom.
>I
>ground off the globs and refired. Now it is a VAAAZ, not a vase! :)
>
>I also high fired some stoneware, it was gross. I brushed on some cone 04
>glaze, a commercial crystal type, I think it was called alligator, and
>fired
>again to 04. Turned out to be one of my favorites.
>
>______________________________________________________________________________
>Send postings to clayart@lsv.ceramics.org
>
>You may look at the archives for the list or change your subscription
>settings from http://www.ceramics.org/clayart/
>
>Moderator of the list is Mel Jacobson who may be reached at
>melpots@pclink.com.
_________________________________________________________________
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Bobbruch1@AOL.COM on wed 20 mar 02
I didn't see the original post, but the reason the cone 10 mug blew up might
not only have been the H2O. Refired pieces have more issues with thermal
shock than bisqued work, and they need to be fired much more slowly through
1000 degrees F.
<<<<
<<
<<been sitting around for awhile and apparently had been out in the rain and
had absorbed some moisture. It blew into the tiniest pieces, all over
everything in the kiln.
cyberscape on wed 20 mar 02
Hi Rebecca,
Some glazes are more successfully applied to fired stoneware than
others. Rutile glazes often work well, because it does not take too
much to shift previously fired surfaces and they tend to stick fairly
well. Then you can let the rutile glaze dry and spray other glazes over
it for intesting effects. Spraying often solves the coverage problem,
if you have the patience to let each built-up layer dry. Remember to
wait until a sprayed layer gets chalky looking before appling more. If
the glaze starts to drip, you won't get any more coverage. Use an HVLP
spray gun. It leaves much more glaze on gloss surfaces than regular
spray guns do becuase the transfer takes place with much lower
pressure. Also, if you heat up the surface first by putting it out in
the sun or setting it on top of the bisquit kiln for a little while, the
glaze will stick better.
You can also add CMC or some other gum to the glaze and it will stick to
the fired surfaces better. Finally, you can apply lower temperature
glazes and fire down for different effects. Most commercial glazes have
gums in them, so that they will stick to vitreous surfaces. See you
next week. :)
Harvey Sadow
Celia Littlecreek on wed 20 mar 02
The pot with the globs, I just put in the next kiln load. The one that I
put the low fir glaze on, I just heated the pot in the oven and painted the
glaze on. Check the archives, there has been bunches of messages about
re-glazing
----- Original Message -----
From: "Judith Frederick"
To:
Sent: Wednesday, March 20, 2002 5:37 AM
Subject: Re: refiring
> how did you get the glaze to adhere to the already glazed surface to
refire
> the piece?
>
cindy on fri 17 mar 06
I was firing my electric kiln to cone 5 and the breaker switched off
during firing. I'm not sure how long it had been off and I didn't want to
overfire my pots so I turned my kiln off and thought I would try to refire
from room temperature. Does anyone know anything about doing this?
Marcia Selsor on fri 17 mar 06
Just start over. No problem.
On Mar 16, 2006, at 11:56 PM, cindy wrote:
> I was firing my electric kiln to cone 5 and the breaker switched off
> during firing. I'm not sure how long it had been off and I didn't
> want to
> overfire my pots so I turned my kiln off and thought I would try to
> refire
> from room temperature. Does anyone know anything about doing this?
>
Marcia Selsor
http://marciaselsor.com
William & Susan Schran User on fri 17 mar 06
On 3/17/06 1:56 AM, "cindy" wrote:
> I was firing my electric kiln to cone 5 and the breaker switched off
> during firing. I'm not sure how long it had been off and I didn't want to
> overfire my pots so I turned my kiln off and thought I would try to refire
> from room temperature.
You can re-fire with no problem, but you may want to go a bit slower at the
beginning of the firing if the pots were fired almost to ^5.
But before that, you need to find out why the breaker kicked off.
Has this happened before? Is breaker and line sized correctly? Breakers can
go bad or are found to be defective. Is the toggle switch of the breaker
loose?
All connections need to be checked.
If it's plug & outlet set up, unplug and check condition of both.
You should remove the electrical boxes (unplug kiln) from the kiln and check
conditions of the wiring.
If you're uncomfortable doing all this, then get someone familiar with kilns
or electrical work to help.
You may find nothing, but best to check it out.
-- William "Bill" Schran
Fredericksburg, Virginia
wschran@cox.net
wschran@nvcc.edu
Lisa E on tue 30 jan 07
> I have a couple of pieces I glazed and I am not happy with the results. I
> bumped them while the glaze still wet and it is very noticeable now that it
> is fired.
>
> Can I glaze those areas again and re-fire it to ^6 again?
>
> Regards,
> --
> Lisa E
> Sunny Daze Design Pottery Studio
> SunnyDazeDesign@gmail.com
> Squamish, BC Canada
>
--
Lisa E
Sunny Daze Design Pottery Studio
SunnyDazeDesign@gmail.com
Squamish, BC Canada
www.lisaelbertsen.com http://picasaweb.google.com/SunnyDazeDesign
Bob Hanlin on tue 30 jan 07
Lisa=0AI've refired some pieces over at c6...some did fine, some cracked, s=
ome looked like they'd been patched, some looked better...try it and see.=
=0AIn the long run it's only clay and electricity.=0A=0ABob=0A=0A=0A----- O=
riginal Message ----=0AFrom: Lisa E =0ATo: CLAYA=
RT@LSV.CERAMICS.ORG=0ASent: Tuesday, January 30, 2007 10:24:03 AM=0ASubject=
: Re: Refiring=0A=0A=0A> I have a couple of pieces I glazed and I am not ha=
ppy with the results. I=0A> bumped them while the glaze still wet and it i=
s very noticeable now that it=0A> is fired.=0A>=0A> Can I glaze those areas=
again and re-fire it to ^6 again?=0A>=0A> Regards,=0A> --=0A> Lisa E=0A> S=
unny Daze Design Pottery Studio=0A> SunnyDazeDesign@gmail.com=0A> Squamish,=
BC Canada=0A>=0A=0A=0A=0A--=0ALisa E=0ASunny Daze Design Pottery Studio=0A=
SunnyDazeDesign@gmail.com=0ASquamish, BC Canada=0A=0Awww.lisaelbertsen.com =
http://picasaweb.google.com/SunnyDazeDesign=0A=0A__________________________=
____________________________________________________=0ASend postings to cla=
yart@lsv.ceramics.org=0A=0AYou may look at the archives for the list or cha=
nge your subscription=0Asettings from http://www.ceramics.org/clayart/=0A=
=0AModerator of the list is Mel Jacobson who may be reached at melpots@pcli=
nk.com.
Bacia Edelman on thu 1 feb 07
Lisa: It is worth refiring. Refiring always means taking a risk. Risks
are worth
taking == to grow in one's work. I also fire to c/6 (and to c/04 at
times). Certain
glazes do better at a slightly lower temp. in refiring. If they are glossy and
could possibly run, I would try the cooler part of the kiln, if that
exists, or
cone 5 or 5 and 1/2 or set a programmed firing to less than 2180 F.
You say, "glaze those areas again." Do you use a spray gun? If yes, the
repair
is less obvious if glaze is sprayed at that area ( on warmed pot) so that
there is not
a noticeable blob where you bumped the glaze originally.
Good luck.
Bacia
> I have a couple of pieces I glazed and I am not happy with the results. I
> bumped them while the glaze still wet and it is very noticeable now that it
> is fired.
>
> Can I glaze those areas again and re-fire it to ^6 again?
>
> Regards,
> --
> Lisa E
> Sunny Daze Design Pottery Studio
> SunnyDazeDesign@gmail.com
> Squamish, BC Canada
>
Bacia Edelman
Madison, Wisconsin http://users.skynet.be/russel.fouts/bacia.htm
http://www.silverhawk.com/artisan/clay/edelman/index.html
Chaeli Sullivan on tue 16 oct 07
Hello All
After a piece has been reduction fired in a kiln which didn't get up to
glaze temperatures (needed Cone 8 but kiln maxed out at 1900 degrees F)--
Can these pieces be refired to Cone 8 without adding a different glaze?
Just put back in a kiln and refired, "as is"? And will the results be the
originally intended colors?
Thanks in advance for the help.
Chae
Maggie Jones on tue 16 oct 07
yes with a good preheat to avoid thermal shock.
m
On Tue, 16 Oct 2007 13:48:10 -0500 Chaeli Sullivan
writes:
> Hello All
> After a piece has been reduction fired in a kiln which didn't get up
> to
> glaze temperatures (needed Cone 8 but kiln maxed out at 1900 degrees
> F)--
> Can these pieces be refired to Cone 8 without adding a different
> glaze?
> Just put back in a kiln and refired, "as is"? And will the results
> be the
> originally intended colors?
> Thanks in advance for the help.
> Chae
>
>
_________________________________________________________________________
_____
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>
> You may look at the archives for the list, post messages, or change
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> subscription settings here: http://www.acers.org/cic/clayart/
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