Llewellyn Kouba on wed 20 jun 01
I am ready to glaze fire early tomorrow. I finished up the last pieces for
the gas kiln in anticipation for a wonderful cone 9 firing. The last
pieces were put in the kiln about 4:00 pm today. Although I have done this
many times I am always a bit nervous if the newly glazed pieces are 'dry'
enough. I can say I have never had a disaster with my methods but still
always wonder. I do not once fire but these are all pre - bisqued items .
(So why not wait a day they say. I go on vacation now any day and figured
I don't have a day to spare) I light the basso switch only and let a bit
of heat warm up the (45 cu ft) kiln and then in the evening start only one
of the pilots to drive off the moisture. I remember from school there was
a certain cutoff point that the instructor would not allow you to have
pieces in the kiln if they were still wet or was that just her way of
making the late students get in gear? In any case I imagine the bigger
fear is if greenware holds moisture than if an already temped bisque glazed
item is still damp. As I mention I have had no troubles but even after
many firings always wonder if all is - A- OK in the dark kiln and a place
where I can not see them again. I await the mystery of the fire.
Three oversized shelves and some nice three dimensional plates and wouldn't
want to lose a thing. When I come back from Vacation I should have a cooled
kiln to inspect and hopefully will be just like another Christmas of
wonderful things.
Llewellyn Kouba
Abbey Pottery
http://www.assumptionabbey.com/Pottery
Snail Scott on thu 21 jun 01
At 07:53 PM 6/20/01 -0600, you wrote:
>...I am always a bit nervous if the newly glazed pieces are 'dry'
>enough. >
>Llewellyn Kouba
Bisque is more porous than greenware, which allows
trapped moisture to escape easily. Also, bisque is
stronger than greenware, so any small pockets of
moisture (which turn to steam in firing) are less
likely to break the clay apart.
The only time I've seen a problem with explosions
of bisqued clay was with a friend's work that was
underglazed, fired, then glazed and refired. The
underglaze covered most of the piece. Apparently
the moisture from glazing got beneath the vitrified
underglaze layer and couldn't escape again. (Sort
of like having a cracked headlight; the water gets
in, but never finds its way out again.) Even after
drying for a week and firing slowly, they all still
blew up, mostly around the base, where the moisture
was probably settling.
(This was pretty thick sculptural work; I suspect
that thinner work has a better chance of drying.
My own sculpture has never had this problem, even
though I build 1/2"-3/4" thick fairly often. This
stuff was much thicker.)
I have also seen a similar problem when glazed
earthenware is re-glazed: the moisture gets though
any crazing, and through unglazed feet, but can't
escape as easily. Re-glazed stoneware seems much
less subject to this particular problem, since the
more vitrified clay simply absorbs less moisture
during the re-glazing.
-Snail
Marcella Smith on thu 21 jun 01
Hello Llewellyn,
If you have ever been in the same room as a kiln filled with damp pots
exploding, you will know that there is no wonder at all. It is a loud
noise, nothing mysterious about it, you aren't looking in the darkness
wondering what may be happening, YOU KNOW IT, with LOUD BANGS as they
explode and hit the walls of those soft kiln bricks and other nice pots.
I used to wonder till I lost everything in my small kiln to an exploding (A
rushed, I thought dried ceramic sculpture), OH MY GOSH, I was in a panic,
hit the breaker, but finally when I was able to the cooled down kiln, all I
had left was what I used a shop vac to clean it out and pull pieces of
pottery out of the walls.
If it is quite, you are fine
Marcella
***Serf on over to www.livinggallery.cc for the latest in fine-art available
for your home or office! Check out the WEEKLY SPECIALS!!***
----- Original Message -----
From: "Llewellyn Kouba"
To:
Sent: Wednesday, June 20, 2001 9:53 PM
Subject: Wet bisque ware being fired
> I am ready to glaze fire early tomorrow. I finished up the last pieces
for
> the gas kiln in anticipation for a wonderful cone 9 firing. The last
> pieces were put in the kiln about 4:00 pm today. Although I have done
this
> many times I am always a bit nervous if the newly glazed pieces are 'dry'
> enough. I can say I have never had a disaster with my methods but still
> always wonder. I do not once fire but these are all pre - bisqued items .
> (So why not wait a day they say. I go on vacation now any day and figured
> I don't have a day to spare) I light the basso switch only and let a bit
> of heat warm up the (45 cu ft) kiln and then in the evening start only one
> of the pilots to drive off the moisture. I remember from school there was
> a certain cutoff point that the instructor would not allow you to have
> pieces in the kiln if they were still wet or was that just her way of
> making the late students get in gear? In any case I imagine the bigger
> fear is if greenware holds moisture than if an already temped bisque
glazed
> item is still damp. As I mention I have had no troubles but even after
> many firings always wonder if all is - A- OK in the dark kiln and a place
> where I can not see them again. I await the mystery of the fire.
>
> Three oversized shelves and some nice three dimensional plates and
wouldn't
> want to lose a thing. When I come back from Vacation I should have a
cooled
> kiln to inspect and hopefully will be just like another Christmas of
> wonderful things.
>
> Llewellyn Kouba
> Abbey Pottery
>
> http://www.assumptionabbey.com/Pottery
>
>
____________________________________________________________________________
__
> 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.
>
Llewellyn Kouba on fri 22 jun 01
Marcella,
I also once had the top blow off of a large 3 foot urn. I had curred it for
months and thought it was dry and when I put it in the kiln I came back
latter and saw shards at the burner end. It had blown off around oven
temp. I lost the carved piece , lots of labor but recycled the clay as it
hadn't gone to temp yet. Live and learn...but fortunately I have never had
a GLAZE item blow up. that must be a mess.
Llewellyn
At 07:19 PM 6/21/2001 -0400, you wrote:
>Hello Llewellyn,
>If you have ever been in the same room as a kiln filled with damp pots
>exploding, you will know that there is no wonder at all. It is a loud
>noise, nothing mysterious about it, you aren't looking in the darkness
>wondering what may be happening, YOU KNOW IT, with LOUD BANGS as they
>explode and hit the walls of those soft kiln bricks and other nice pots.
>I used to wonder till I lost everything in my small kiln to an exploding (A
>rushed, I thought dried ceramic sculpture), OH MY GOSH, I was in a panic,
>hit the breaker, but finally when I was able to the cooled down kiln, all I
>had left was what I used a shop vac to clean it out and pull pieces of
>pottery out of the walls.
>If it is quite, you are fine
>Marcella
>
>
>***Serf on over to www.livinggallery.cc for the latest in fine-art available
>for your home or office! Check out the WEEKLY SPECIALS!!***
>----- Original Message -----
>From: "Llewellyn Kouba"
>To:
>Sent: Wednesday, June 20, 2001 9:53 PM
>Subject: Wet bisque ware being fired
>
>
> > I am ready to glaze fire early tomorrow. I finished up the last pieces
>for
> > the gas kiln in anticipation for a wonderful cone 9 firing. The last
> > pieces were put in the kiln about 4:00 pm today. Although I have done
>this
> > many times I am always a bit nervous if the newly glazed pieces are 'dry'
> > enough. I can say I have never had a disaster with my methods but still
> > always wonder. I do not once fire but these are all pre - bisqued items .
> > (So why not wait a day they say. I go on vacation now any day and figured
> > I don't have a day to spare) I light the basso switch only and let a bit
> > of heat warm up the (45 cu ft) kiln and then in the evening start only one
> > of the pilots to drive off the moisture. I remember from school there was
> > a certain cutoff point that the instructor would not allow you to have
> > pieces in the kiln if they were still wet or was that just her way of
> > making the late students get in gear? In any case I imagine the bigger
> > fear is if greenware holds moisture than if an already temped bisque
>glazed
> > item is still damp. As I mention I have had no troubles but even after
> > many firings always wonder if all is - A- OK in the dark kiln and a place
> > where I can not see them again. I await the mystery of the fire.
> >
> > Three oversized shelves and some nice three dimensional plates and
>wouldn't
> > want to lose a thing. When I come back from Vacation I should have a
>cooled
> > kiln to inspect and hopefully will be just like another Christmas of
> > wonderful things.
> >
> > Llewellyn Kouba
> > Abbey Pottery
> >
> > http://www.assumptionabbey.com/Pottery
> >
> >
>____________________________________________________________________________
>__
> > 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.
> >
>
>______________________________________________________________________________
>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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