Drake Ash on sat 14 apr 12
i just want to ask the experts...is it always bad to dry things fast--like
a long preheat in my kiln? no attachments on these. they are knitting bowls
that i am trying to get ready for a date quite close to today's. i have to
admit, a few are in my oven as i write :)
thanks,
drake
James Freeman on sat 14 apr 12
On Sat, Apr 14, 2012 at 10:14 AM, Drake Ash wrote:
i just want to ask the experts...is it always bad to dry things fast--like
a long preheat in my kiln?
Drake...
I'm not an expert, but I do it all the time with thrown work. Trim it,
straight into the kiln at leather hard, then fire away with my normal ramp,
but with a 2 or 3 hour preheat. I throw pretty thin, so more time may be
needed if you throw thicker. I lost one small piece a couple of weeks ago,
an extruded piece, but that is the only one I can think of in years of
doing this, and everything else in the kiln, equally wet, was just fine.
Note, I don't do this with hand-built or assembled work, which I don't
think would survive without cracking.
I read an article a few years back, I believe in Ceramics Monthly, by a guy
who fires completely wet work in an electric kiln, with no preheat and no
slow heating! He claimed that as long as the kiln is tight, that is no
ventilation, then the pressure of the steam in the kiln would counteract
the force of the steam trying to violently escape from the piece, resulting
in even and rapid drying with no explosions. Intriguing concept, though I
have trouble believing that an ordinary electric kiln would be tight
enough. I have never tried it.
Good luck.
...James
James Freeman
"Talk sense to a fool, and he calls you foolish."
-Euripides
http://www.jamesfreemanstudio.com
http://www.flickr.com/photos/jamesfreemanstudio/
http://www.jamesfreemanstudio.com/resources
Robert Harris on sat 14 apr 12
I totally agree with James. Additionally I would add that if stuff is
pretty damp I use a preheat of 1 hour at 200F and then a couple of
hours at 280F.
While 280F is significantly above the boiling point of water, it seems
to be low enough that pots don't explode, but significantly decreases
the pre-heat time needed for thicker pieces (e.g. Casseroles or large
canisters etc). In addition I would fire as much as possible upside
down, as bases usually have a problem drying on kiln shelves.
Also don't forget to prop the kiln lid open about an inch or so while
the steam escapes. Another thing I do is, after closing the lid for a
few minutes, put a cool piece of glass in front of the peephole. If it
steams up, you're not done pre-heating. If it remains dry, you're good
to go.
Robert
On Sat, Apr 14, 2012 at 12:49 PM, James Freeman
wrote:
> On Sat, Apr 14, 2012 at 10:14 AM, Drake Ash wrote:
> i just want to ask the experts...is it always bad to dry things fast--lik=
=3D
e
> a long preheat in my kiln?
>
>
>
>
> Drake...
>
> I'm not an expert, but I do it all the time with thrown work. =3DA0Trim i=
t,
> straight into the kiln at leather hard, then fire away with my normal ram=
=3D
p,
> but with a 2 or 3 hour preheat. =3DA0I throw pretty thin, so more time ma=
y =3D
be
> needed if you throw thicker. =3DA0I lost one small piece a couple of week=
s =3D
ago,
> an extruded piece, but that is the only one I can think of in years of
> doing this, and everything else in the kiln, equally wet, was just fine.
> Note, I don't do this with hand-built or assembled work, which I don't
> think would survive without cracking.
>
> I read an article a few years back, I believe in Ceramics Monthly, by a g=
=3D
uy
> who fires completely wet work in an electric kiln, with no preheat and no
> slow heating! =3DA0He claimed that as long as the kiln is tight, that is =
no
> ventilation, then the pressure of the steam in the kiln would counteract
> the force of the steam trying to violently escape from the piece, resulti=
=3D
ng
> in even and rapid drying with no explosions. =3DA0Intriguing concept, tho=
ug=3D
h I
> have trouble believing that an ordinary electric kiln would be tight
> enough. =3DA0I have never tried it.
>
> Good luck.
>
> ...James
>
> James Freeman
>
> "Talk sense to a fool, and he calls you foolish."
> -Euripides
>
> http://www.jamesfreemanstudio.com
> http://www.flickr.com/photos/jamesfreemanstudio/
> http://www.jamesfreemanstudio.com/resources
--=3D20
----------------------------------------------------------
Fredrick Paget on sat 14 apr 12
Well let's try it. I often set stuff on a wire shelf above the heater.
Fred
>
>Drake...
>
>snip
>
>I read an article a few years back, I believe in Ceramics Monthly, by a gu=
y
>who fires completely wet work in an electric kiln, with no preheat and no
>slow heating! He claimed that as long as the kiln is tight, that is no
>ventilation, then the pressure of the steam in the kiln would counteract
>the force of the steam trying to violently escape from the piece, resultin=
g
>in even and rapid drying with no explosions. Intriguing concept, though I
>have trouble believing that an ordinary electric kiln would be tight
>enough. I have never tried it.
>
>Good luck.
>
>...James
>
>James Freeman
>
>"
--
Twin Dragon Studio
Mill Valley, CA, USA
John Hesselberth on sat 14 apr 12
Hi Drake,
You can dry fast IF you dry evenly. By that I mean uniformly thick walls =
=3D
and good airflow around all sides of a pot. If you set the pot on a =3D
solid shelf and/or have walls that are thick on the bottom and thin on =3D
top, you will probably have a problem. Most craft schools (e.g. =3D
Arrowmont) and some community studios have dry boxes where the pots sit =3D
on a screen and a fan keeps the air moving. They work pretty well for =3D
well-constructed work and you can easily go from freshly thrown to bone =3D
dry overnight. Open vessels like bowls do better than more closed forms =3D
like bottles. They, of course, have an incentive to dry quickly so they =3D
can have fired work at the end of a week-long workshop.
Regards,
John
On Apr 14, 2012, at 10:14 AM, Drake Ash wrote:
> i just want to ask the experts...is it always bad to dry things =3D
fast--like
> a long preheat in my kiln? no attachments on these. they are knitting =3D
bowls
> that i am trying to get ready for a date quite close to today's. i =3D
have to
> admit, a few are in my oven as i write :)
>=3D20
> thanks,
> drake
The dumbest people I know are those that know it all. Malcolm Forbes
John Hesselberth
john@frogpondpottery.com
Drake Ash on sat 14 apr 12
thank you, everyone! all very interesting, and i am going to move forward
with these ideas. i will report back--and i really appreciate your advice.
a drying rack seems like a great idea for the future, too.
crossing my fingers,
drake
On Sat, Apr 14, 2012 at 1:40 PM, Fredrick Paget wrote:
> Well let's try it. I often set stuff on a wire shelf above the heater.
>
> Fred
>
>
>> Drake...
>>
>> snip
>>
>>
>> I read an article a few years back, I believe in Ceramics Monthly, by a
>> guy
>> who fires completely wet work in an electric kiln, with no preheat and n=
o
>> slow heating! He claimed that as long as the kiln is tight, that is no
>> ventilation, then the pressure of the steam in the kiln would counteract
>> the force of the steam trying to violently escape from the piece,
>> resulting
>> in even and rapid drying with no explosions. Intriguing concept, though=
I
>> have trouble believing that an ordinary electric kiln would be tight
>> enough. I have never tried it.
>>
>> Good luck.
>>
>> ...James
>>
>> James Freeman
>>
>> "
>>
>
> --
> Twin Dragon Studio
> Mill Valley, CA, USA
>
Lis Allison on sat 14 apr 12
On April 14, 2012, Drake Ash wrote:
> i just want to ask the experts...is it always bad to dry things
> fast--like a long preheat in my kiln? no attachments on these. they
> are knitting bowls that i am trying to get ready for a date quite
> close to today's. i have to admit, a few are in my oven as i write :)
>
A lot depends on the clay. A cone 6 porcelain I use can be dried fast very
nicely, but a cone 6 stoneware with grog and specks not.
Leave the kiln lid up and keep an eye on it and you'll get a feel for how
well your stuff is drying. BTW, you may get some 'dragging' on the bases
of the bowls as they shrink, so check them and sand the bisque if they
have gotten rough.
Lis
--
Elisabeth Allison
Pine Ridge Studio
website: www.pine-ridge.ca
Pottery blog: www.studio-on-the-ridge.blogspot.com
Garden blog: www.garden-on-the-ridge.blogspot.com
Neal on sun 15 apr 12
I learned in a workshop that Pete Pinnell did in Lancaster, PA,
about using the microwave at 30 percent power to speed pots
along. I usually do this to get pots ready to trim, but I have
microwaved the pots further to get them ready for bisquing.
The secret is not to let the pots get too hot, just warm enough
to have some steam leaving them but not to where they will
explode. They will continue to steam after removing them
from the microwave. Sometimes I will microwave them then
put them under plastic again to help even out the moisture
content.
Neal O'B.
Raleigh, NC
Rimas VisGirda on sun 15 apr 12
James wrote:=3D0A=3D0AI read an article a few years back, I believe in Cera=
mics=3D
Monthly, by a guy=3D0Awho fires completely wet work in an electric kiln, w=
it=3D
h no preheat and no=3D0Aslow heating!=3DA0 He claimed that as long as the k=
iln =3D
is tight, that is no=3D0Aventilation, then the pressure of the steam in the=
k=3D
iln would counteract=3D0Athe force of the steam trying to violently escape =
fr=3D
om the piece, resulting=3D0Ain even and rapid drying with no explosions.=3D=
A0 I=3D
ntriguing concept, though I=3D0Ahave trouble believing that an ordinary ele=
ct=3D
ric kiln would be tight=3D0Aenough.=3DA0 I have never tried it.=3D0A=3D0A=
=3D0AHi Jame=3D
s, here's the long version of a short story about how I came upon, and used=
=3D
, steam bisques... I tend to be fairly regimented, a place for everything a=
=3D
nd everything in its place. So in my first teaching job (1973) I arranged t=
=3D
he ceramics room into what I considered an efficient pattern for moving the=
=3D
student work through the studio. There were shelves for work in progress t=
=3D
hat were also used for drying the work for bisqueing. There were shelves fa=
=3D
cing the electric (bisque) kilns that were labelled BONE DRY WORK ONLY (BDW=
=3D
O) as the students took turns loading and firing the bisques as a learning =
=3D
process they typically didn't have enough of their own work to fill the kil=
=3D
n so used work from the BDWO shelves; when the BDWO shelves got pretty full=
=3D
it was someone's turn to take it upon themselves to load and fire. I don't=
=3D
like to waste time (or energy) so taught a fast bisque schedule which is w=
=3D
hy the BDWO shelves stipulated BONE DRY... One evening while
shutting down for the night I noticed that most of the work on the BDWO st=
=3D
ill had color, that is in some stage of leather hard which pissed me off. S=
=3D
o I tumble loaded most of the kiln, about the size of a Skutt 1027, with th=
=3D
e leatherhard ware. Closed the lid, put in all the peeps, turned all the sw=
=3D
itches to HIGH and went home, I thought to teach those students a lesson! T=
=3D
he next day I went to the studio expecting to have a kiln full of shards, b=
=3D
ut to my complete surprise and dumbfoundment (is that a word?) everything w=
=3D
as a nice pink and not one piece had exploded...=3D0A=3D0AA few years later=
, ha=3D
ving been a rocket scientist after college I was also interested in the eng=
=3D
ineering aspects of ceramics and attended a ceramics engineering conference=
=3D
at Purdue. One of the presentations was by an engineer that had perfected =
=3D
a method of firing wet ceramics from forming to finished product in a matte=
=3D
r of hours. I don't remember what the work was but he did this by pressuriz=
=3D
ing a kiln and heating it quickly, say 15 minutes to 2000F then using the r=
=3D
emaining 1 3/4 hrs to evenly bleed off the pressure (steam) and the result =
=3D
was fired work at 2000F.=3D0A=3D0AThinking back to my failed lesson, I figu=
red =3D
by turning all the elements on H with everything shut, the heat generated e=
=3D
nough steam before the work got to 212F to pressurize the kiln and as in th=
=3D
e above mentioned kiln the vapor pressure prevented the H2O IN the ware fro=
=3D
m changing phase and as the steam slowly vented through the gap between the=
=3D
door and kiln wall the superheated H2O migrated out of the clay just as it=
=3D
would if drying on a shelf at room temperature... So back in the studio, I=
=3D
tried it by putting bowls of water into the kiln along with leatherhard wa=
=3D
re closing everything up and turning all elements on H and walking away -an=
=3D
d found it to work. At that time, mid 70's I didn't find any practical use =
=3D
for the technique so it got shelved and forgotten somewhere in my brain...=
=3D
=3D0A=3D0AUntil I taught a sabbatical replacement for Soldner at Scripps an=
d Cl=3D
aremont Graduate School in 1989... Paul didn't have any electric kilns and =
=3D
some of the students wanted to do electric work rather than figure out how =
=3D
to accomplish a clean atmosphere in a fuel kiln. A second advantage of an e=
=3D
lectric was the kiln sitter gadget... So I bought an electric kiln for the =
=3D
students to use. One day one of the undergrads needed something FAST so I e=
=3D
xplained the principle of a steam bisque and said try it and good luck... N=
=3D
ext day he came in with a long face and said the steam bisque didn't work a=
=3D
nd all his work exploded... As it turns out he tried the "steam bisque" in =
=3D
a fuel kiln! I guess I forgot to stipulate that he should use the electric =
=3D
as it's necessary to have a sealed system...=3D0A=3D0ASome years later, at =
Illi=3D
nois Wesleyan University, I wanted ceramics to do some self-promotion. So w=
=3D
e advertised a "Raku Weekend" opened to the the campus as well as the commu=
=3D
nity. People would come in on Saturday and spend the morning and early afte=
=3D
rnoon making work with the help of the ceramic students. We loaded the stif=
=3D
fened ware into an electric kiln along with some (bisque) bowls of water, s=
=3D
ealed it off and did the "all on High" trick. Next morning, the makers woul=
=3D
d come in and glaze their pieces and we rakued in the afternoon -everyone w=
=3D
ent home happy and needing to wash the smoke smell out of their clothes... =
=3D
We stopped the clay work in the early afternoon as we found that loading we=
=3D
t pots resulted in them "melting" by the vapor pressure pushing H2O (steam)=
=3D
into the ware... so we would put the work in front of a fan for a couple o=
=3D
f hours to where it got "stiff" if not leatherhard.=3D0A=3D0A=3D0AFor a num=
ber of=3D
years there was a faculty wife, Joyce Kavanaugh, that worked in the studio=
=3D
and became an ex post facto studio assistant/manager... She took it upon h=
=3D
erself to experiment with the technique and wrote a handout with her findin=
=3D
gs. This was before I got digital so this morning I looked and found a hard=
=3D
copy in my files. I don't want to retype the thing into a document, but if=
=3D
anyone is interested, email me with "steam bisque" in the subject line and=
=3D
I'll send you a jpeg of the page as an attachment...=3D0A=3D0A-Rimas=3D0A
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