Stephani Stephenson on sun 18 sep 11
Shula, i can tell you my experience with single firing, recognizing it ma=
=3D
y
not all apply for your ware.
i have single fired tile and also things like sinks, fountain basins, wa=
=3D
ll
sconces etc.
i used the same clay and glazes as when doing separate bisque and glaze f=
=3D
irings
i did usually find that using a glaze with 10% or more clay in it works b=
=3D
est.
my ware was usually fairly thick, so you may need to adapt the process fo=
=3D
r=3D20
very thin vessels.
i did occasionally spray the glaze and did nothing different except for=
=3D
handling, mentioned below.
i also poured , as well as dipped and very often floated glaze on with a=
=3D
big mop brush.
my glazes tended to be thicker than a standard stoneware glaze. heavier
than cream ,tho certainly not yogurt.:). i tried to minimize the water, y=
=3D
et
i still needed to maintain the pouring or dipping quality. you could=3D2=
0=3D
experiment with lowering water by using a deflocculant. i never did this.=
=3D
when i sprayed of course the glaze was thinner.=3D20
the goal is to get the glaze onto the piece in a relatively fast and
efficient manner.
once liquid hits the clay it will soak n a bit and begin to weaken it. th=
=3D
is
is more crucial with thin pieces.=3D20=3D20
I glazed when the piece was bone dry. i worked with bone dry ware becau=
=3D
se
the glaze soaked in just a bit, enough to adhere. i preferred this over
glazing when leather hard , because i liked that bit of adhesion, but tha=
=3D
t
is just me.=3D20
remember that glaze liquid doesn't soak into either leather or bone dry w=
=3D
ork
nearly as much as bisque, so it will look like you have a much thicker co=
=3D
at
sitting on the surface. More of the water will evaporate from the surfac=
=3D
e
rather than soaking into the body . this may change the fired appearance =
=3D
of
some glazes, but for the most part, my glazes looked similar whether they=
=3D
were single fired or not.
i also found that i either needed to move the piece immediately after
glazing, before the glaze water has really permeated OR let it sit about
15-20 minutes, then move it . it is most fragile during that first 15 or=
=3D
20
minutes.
i often used this technique for large work which was difficult to load an=
=3D
d
unload , also to save fuel/firing costs on this type of work, which took=
=3D
up
a lot of space in the kiln. i also used it on very large tiles sometimes =
=3D
,
where losses might increase with a second firing.=3D20
I fired the work just as i would a bisque firing ,up through water evap,=
=3D
=3D20
and organic material burnout and then like any bisque or glaze firing
through quartz inversion and on up=3D20
hope this helps
Stephani
Pottery by John on sun 18 sep 11
On 9/18/2011 1:55 PM, Shula wrote:
> All of this talk about single firing has convinced me that I should give =
it a try. However, before I do, I have several questions.
>
>
You will probably get a number of differing opinions on this, but what I
do is pour the interior glazes into and out of the bone dry pots and
spray the outside. I cannot imagine dipping, but it may be possible if
your pot is shaped so you can hold on to it. You would have to really
careful and use no glaze tongs to help, as they would most likely crush
the pot walls. When bone dry the pots are very absorptive and takes
glazes differently than bisque, in my opinion.
After glazing, I start like I do for a bisque firing where my pots are
not bone dry. I don't wait for the pots to dry out any, unless it meets
my schedule for other reasons. I candle overnight with one switch on
low (kiln sitter type, this keeps my temperature below 200 F), and then
follow my usual bisque routine, but slow down the rate of rise, as any
organics have to burn out before the glaze melt starts and seals them
in, or makes them give bubbling/pinhole issues. In kiln sitter kiln, I
crash cool down to 1850-1900, then adjust my firing down to 150 F per
hour until 1500, or so, then crash cool the rest of the way. On my
website, on the Steven Hill workshop page, there are examples of pots
cooled this way that used Steven Hill glazes, and there is another page
with a slide show of single fired pots using a variety of glazes, some
home mixed and some commercial.
I don't do this all the time, but didn't have a particular problems, if
I go slow a steady. Enjoy the experiment.
John Lowes
Sandy Springs, Georgia, USA
http://wynhillpottery.weebly.com
Shula on sun 18 sep 11
All of this talk about single firing has convinced me that I should give it=
a try. However, before I do, I have several questions.
- When should I glaze the pieces - when they are bone dry or ?
- On bisque ware, I spray the glaze on most pieces and dip a minority of pi=
eces. If I spray glaze on greenware, what must I do differently? And what a=
bout dipping; what do I need to do differently?
- Firing - most of my glazes are from MC6G and control cooling from 1900-14=
00 during the glaze firing. If I single fire, I assume I would follow the s=
ame slow cool. What about getting to temperature? Should I do a preheat (ra=
mp of 60 degrees F / hr until 200 degrees, hold and then fire as normally f=
or a glaze firing? If so, how long should I hold at 200? I also hold at con=
e 5 for an hour. Should I hold for an hour or? Should I consider another ap=
proach?
Usual glaze firing:
1: ramp 200 degrees F to 200
2: ramp 275 degrees F to 2000
3: ramp 150 degrees F to cone 5; hold 30 - 60 minutes
4: ramp 999 degrees F to 1900 (takes about an hour)
5: ramp 125 degrees F to 1400
Thanks for your help.
Shula
Shula
Desert Hot Springs, California USA
www.claymystique.etsy.com
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