Dayton Grant on thu 14 feb 08
If you dip the very thin wares while they are very hot, (right out of the b=
isque or reheat them just before glazing) they will carry a thick coat of g=
laze without becoming saturated. };^)> =20
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Steve Slatin on fri 15 feb 08
Stephanie -- I've done it a few times; the warm pots
unquestionably acquire a thicker layer of glaze.
Sometimes it appears that you only have a
thin application, because the glaze surface
dries almost instantly, but it can actually be
rather thick.
Remember, though, that there are a whole series
of independently adjustable variables here, and
changing any one of them can change the final
result. Less water in the glaze will give you a
thicker layer of glaze. A longer 'hold' in the glaze,
if you are a dip and pour kind of potter, will do
so as well. A longer wait between bisqueing and
glazing will generally result in a thinner layer (more
time for the clay to re-absorb moisture from the
air). Rinsing your bisque will greatly reduce
absorbtion.
If you want to see the result of a change in
a single variable -- like glazing a warm pot
vs. a cool one, you should eliminate variation
in all of the other variables. You'd have to bisque
two very similar pots at the same time, stir up the
glaze really, really well, bisque one hot, and
then wait a few hours for complete cooling
(but not long enough for air-moisture re-absorbtion!)
re-stir, and glaze the second pot.
best -- Steve Slatin
Stephanie Wright wrote:
This is interesting - something I have never heard before. Have others on
this list tried glazing hot bisque with success? Are there any problems to
watch out for with adhesion, etc?
By the way Dayton, your most recent posts were much more clear, to the
point, easier to read, and significantly less confrontational. Thank you!
Stephanie
---------------------------------
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William & Susan Schran User on fri 15 feb 08
On 2/15/08 7:16 AM, "Stephanie Wright" wrote:
> This is interesting - something I have never heard before. Have others on
> this list tried glazing hot bisque with success? Are there any problems to
> watch out for with adhesion, etc?
Yes, I've heard/used this method.
Hot clay would cause quicker evaporation of the water.
Same thing for re-glazing an already glaze fired pot.
Bill
--
William "Bill" Schran
wschran@cox.net
wschran@nvcc.edu
http://www.creativecreekartisans.com
Stephanie Wright on fri 15 feb 08
This is interesting - something I have never heard before. Have others on
this list tried glazing hot bisque with success? Are there any problems to
watch out for with adhesion, etc?
By the way Dayton, your most recent posts were much more clear, to the
point, easier to read, and significantly less confrontational. Thank you!
Stephanie
vpitelka on sat 16 feb 08
Steve Slatin wrote:
"I can't say that I've done a controlled test of the thinnest thrown pots,
but certainly with a moderately thin wall there's a difference with a longer
dip."
Steve -
It is always a challenge to glaze very thin wares, because the way most of
us glaze our ware (dipping and pouring) of course depends on quick
absorption of the water in order to retain a good coat of glaze on the
surface. Thin wall sections don't have that absorption capacity, and are
easily saturated. If the water isn't soaking in, then the piece will hardly
pick up any coat of glaze at all. In my experience, the best ways to get a
good coat of glaze on a very thin piece are to dip quickly in a slightly
thicker-than-normal glaze, or to warm up the piece ahead of time and dip
quickly in a normal glaze. But in most cases where the wall is not too
thin, then of course a longer dip will always result in a thicker coat of
glaze.
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpitelka@dtccom.net; wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka
William & Susan Schran User on sat 16 feb 08
On 2/16/08 6:40 PM, "Steve Slatin" wrote:
> I agree with the outline of your
> description, though -- largely it's
> a question of water absorbtion
> from the slurry leaving a partially
> dried coating of glaze on the
> wall. But my observation from
> doing overglazing with a different
> appearing glaze is that you can
> always get some additional glaze
> deposited on a pot, even when
> it's pretty well saturated with the
> first glaze (i.e., still damp to the
> touch 10 minutes or so after
> dipping).
Steve,
What you write is true and I advise my students to wait until a glaze
application has dried to the touch before applying a 2nd layer, but don't
try to apply a second layer if the glaze/pot have dried overnight.
Re-wetting a pot covered in a dry glaze will often cause all of the glaze to
peel off the clay. So yes the first glaze can be damp and have 2nd glaze
adhere.
What I was attempting to write about was the application of glaze to a very
thin walled pot, like a small pinch pot with wall thickness 1/16". Dipping a
pot such as this in glaze and holding for a moment would result in a glaze
coat that might not dry for more than an hour because the clay can only
absorb a limited amount of water.
Bill
--
William "Bill" Schran
wschran@cox.net
wschran@nvcc.edu
http://www.creativecreekartisans.com
William & Susan Schran User on sat 16 feb 08
On 2/15/08 7:49 PM, "Steve Slatin" wrote:
> A longer 'hold' in the glaze,
> if you are a dip and pour kind of potter, will do
> so as well. A longer wait between bisqueing and
> glazing will generally result in a thinner layer (more
> time for the clay to re-absorb moisture from the
> air).
If the wall of the pot is rather thin, holding in the glaze longer would not
necessarily allow the glaze to build up much thicker. As the clay takes up
the water, it will reach a saturation point where no more water will be
taken up and it would then be difficult for the glaze to be deposited in the
surface.
I have not found a longer wait between bisque and applying glaze to the
surface to be a significant variable. I doubt that the clay body would
absorb sufficient moisture from the atmosphere that one would be able to
notice when applying the glaze - well, maybe way down south in the middle of
August...
Bill
--
William "Bill" Schran
wschran@cox.net
wschran@nvcc.edu
http://www.creativecreekartisans.com
Steve Slatin on sat 16 feb 08
Bill --
I can't say that I've done a controlled
test of the thinnest thrown pots, but
certainly with a moderately thin
wall there's a difference with a longer
dip.
I agree with the outline of your
description, though -- largely it's
a question of water absorbtion
from the slurry leaving a partially
dried coating of glaze on the
wall. But my observation from
doing overglazing with a different
appearing glaze is that you can
always get some additional glaze
deposited on a pot, even when
it's pretty well saturated with the
first glaze (i.e., still damp to the
touch 10 minutes or so after
dipping).
Likewise for waiting to glaze, I
can provide only anecdotal/
observational input. I've had
the experience of glazing
after doing two bisque loads
back to back, though (my tiny
studio was jammed with unglazed
ware) and it took 4 glaze loads to
get through the backlog, and
almost 3 weeks time. It was
a wet spring, and there was a
definite difference between things
that went into the first kiln load
and the last, and the glazes
were significantly thinner, both
for same-batch glazings and
new mixing.
Best wishes -- Steve S
William & Susan Schran User wrote:
If the wall of the pot is rather thin, holding in the glaze longer would not
necessarily allow the glaze to build up much thicker. As the clay takes up
the water, it will reach a saturation point where no more water will be
taken up and it would then be difficult for the glaze to be deposited in the
surface.
I have not found a longer wait between bisque and applying glaze to the
surface to be a significant variable. I doubt that the clay body would
absorb sufficient moisture from the atmosphere that one would be able to
notice when applying the glaze - well, maybe way down south in the middle of
August...
Bill
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Lee on sun 17 feb 08
On 2/16/08, William & Susan Schran User wrote:
> If the wall of the pot is rather thin, holding in the glaze longer would not
> necessarily allow the glaze to build up much thicker.
This is true. The body becomes saturated and cannot "suck
up" more glaze. If you completely dried the first dip, then a second
would make it thcker, but you have to dry the body first.
> I have not found a longer wait between bisque and applying glaze to the
> surface to be a significant variable. I doubt that the clay body would
> absorb sufficient moisture from the atmosphere that one would be able to
> notice when applying the glaze - well
I have not noticed a difference either, even during
rainyseason here in Japan.
One of the benefits of low bisque and then sponging just
before the glaze application, is that you can, with practice, control
how much water is sponged onto the bisque. For example, you wet
thin ware less than thick ware. Also, using a glaze with less water
in the begining, and starting with thin ware, and then adding water as
you move on to thicker ware, helps adjust the glaze application
according to the thickness of the ware.
My job during my apprenticeship when we were glazing was the
bisque sponger. I would sit with my sponge and bucket of warm water,
between the Foreman and my teacher and I would sponge each pot before
it was deocrated and glazed. I would sponge, center the piece on the
banding wheel, my teacher would do iron decoration, starting with iron
rings on the banding wheel, then I would take the work from my teacher
and hand it to the Foreman who was the main glazer. There were 4
other apprentices and two more craftspersons all busy with other
details while this was going on.
Most potters don't require this level of attention to glaze
thickness application. But my teacher's inlay work always boarder
between being too thin, and too dark or too thick, obscuring the inlay
beneath it. Learning this sensitivity allows me to easily handle
my less rigorous glaze application needs. ;^)
--
Lee in Mashiko, Tochigi Japan
http://mashikopots.blogspot.com/
"Tea is nought but this: first you heat the water, then you make the
tea. Then you drink it properly. That is all you need to know."
--Sen No Rikyu
"Let the beauty we love be what we do." - Rumi
John Britt on sun 17 feb 08
The way I glaze thin ware is to glaze the inside one day and the next day
glaze the outside. Or the other way. Since the absorptive capacity of the
clay is so small you have to out smart it.
Hope it helps,
John Britt
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