Ivor and Olive Lewis on wed 11 feb 04
Dear Friends,
I go along with Richard Aerni on this one.
Having a high thermal mass slows the cooling rate of the kiln and
allows time for crystal inclusions to nucleate and grow.
Helps to give pots "character"
Best regards,
Ivor Lewis. Redhill, South Australia
Lee Love on thu 12 feb 04
Ivor and Olive Lewis wrote:
>Dear Friends,
>I go along with Richard Aerni on this one.
>Having a high thermal mass slows the cooling rate of the kiln and
>allows time for crystal inclusions to nucleate and grow.
>Helps to give pots "character
>
If thermal mass is the primary purpose, a kiln like mine might
make better sense: the interior is softbrick and the exterior is
hardbrick.
You can see photos here, scroll to the bottom:
http://www.livejournal.com/users/togeika/?skip=60
You can see the plans here:
http://potters.blogspot.com/
If I have the room, I've thought that my next kiln might be
made of local building stone on the outside, Oya stone, and softbrick on
the inside.
Lee In mashiko
Ivor and Olive Lewis on fri 13 feb 04
----- Original Message -----
From: "Lee Love"
To:
Sent: Thursday, 12 February 2004 12:09
Subject: Re: Why a Hard Brick Kiln Interior
> Ivor and Olive Lewis wrote:
>
> >Dear Friends,
> >I go along with Richard Aerni on this one.
> >Having a high thermal mass slows the cooling rate of the kiln and
> >allows time for crystal inclusions to nucleate and grow.
> >Helps to give pots "character
> >
>
> If thermal mass is the primary purpose, a kiln like mine
might
> make better sense: the interior is softbrick and the exterior is
> hardbrick.
>
> You can see photos here, scroll to the bottom:
>
> http://www.livejournal.com/users/togeika/?skip=60
>
> You can see the plans here:
>
> http://potters.blogspot.com/
>
> If I have the room, I've thought that my next kiln
might be
> made of local building stone on the outside, Oya stone, and
softbrick on
> the inside.
>
> Lee In mashiko
>
>
______________________________________________________________________
________
> 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.
Ivor and Olive Lewis on fri 13 feb 04
Dear Lee Love,
I would like you to explain the physics of your proposition given the
need to retain as much thermal energy in the kiln as possible to
retard the cooling rate.
I interpret what you write as saying, the lightweight refractory holds
more heat than the dense refractory and the dense refractory does not
conduct heat as well as the refractory insulator.
But your proposal for a new kiln has merit if you do not object to
rapid cooling, provided you "OYA"Stone is not based on Limestone,
Dolomite or chalk
Best regards,
Ivor Lewis. Redhill, South Australia
Christy Pines on sat 14 feb 04
I've read what is in Vince's book regarding crystalline development
during cooling, hoping to find out what you mean when you say "crystal
inclusions add character" but I'm still in the dark. Can you expound?
What does this look like? How is it different from when Vince says that
you must be careful of crystals forming in the clay as crystobalite is a
destructive crystal that decreases durability and thermal shock
resistance in the wares. He does go on to say that below 2200 F and to
about 1800 F, desirable crystals are forning, like mullite crystals that
give strength to high-fired clay and glazes and surface crystals that
give mattness and texture to the glaze. Are these the crystal inclusions
you reference? Are there pictures somewhere?
thanks in advance for furthering my education.
christy in connecticut, getting ready to 2 (count em 2) salt/soda kiln
workshops. cannot wait. throwing my little head off making pots to go
into these wonderful kilns.
>
>
>>Ivor and Olive Lewis wrote:
>>
>>
>>
>>>Dear Friends,
>>>I go along with Richard Aerni on this one.
>>>Having a high thermal mass slows the cooling rate of the kiln and
>>>allows time for crystal inclusions to nucleate and grow.
>>>Helps to give pots "character
>>>
>>>
Lee Love on sat 14 feb 04
On 2004/02/13 9:41:10, clayart@lsv.ceramics.org wrote:
> But your proposal for a new kiln has merit if you do not object to
rapid cooling
>, provided you "OYA"Stone is not based on Limestone,
My kiln is efficent, because of the softbrick on the inside, but
with the hard brick on the outside, it does not cool quickly like an all
softbrick kiln. The fastest I can unload a glaze firing is in 36
hours, only if I crash cool to 1000*C at the end of the firing and then
open the damper at the end of cooling. I'd rather let it cool for 2
complete days.
Oya is mostly sandstone. Oya sand was used for silica in glazes
traditionally. When the German potter was here studying here, Gorden
Gran from near Dresden, he studied with the master kiln builder in
Mashiko. The master kiln builder explained that the first kilns in
Mashiko were built entirerly of stone and not of brick. They were
not good at the highest temperatures, where the stone would start to melt.
Lee In Mashiko
http://mashiko.us
Ivor and Olive Lewis on sun 15 feb 04
Dear Christy Pines,
I am speaking of the "character" of the glaze, not about the potential
of making nasty things happen in the clay body. Rather than getting
large crystals as is done with Zinc rich glazes you can get Titanium
silicate, Iron oxide and other compounds precipitating as small
inclusions in a transparent clear or coloured background. these can
add colour, visual texture and optical reflections which seem to come
from deep within the glaze. I call this "Character"
"Mastering Cone Six Glazes" by Ron Roy and John H. have very good
illustrations of this phenomenon and they discuss this process in
great detail. Another text with illustrations is Emmanuel Cooper,"The
Potter's Book of Glaze Recipes," ill 13.
Enjoy your Salt Glaze Workshops.
Best regards,
Ivor Lewis. Redhill, South Australia
----- Original Message -----
From: "Christy Pines"
To:
Sent: Sunday, 15 February 2004 2:12
Subject: Re: Why a Hard Brick Kiln Interior
> I've read what is in Vince's book regarding crystalline development
> during cooling, hoping to find out what you mean when you say
"crystal
> inclusions add character" but I'm still in the dark. Can you
expound?
> What does this look like? How is it different from when Vince says
that
> you must be careful of crystals forming in the clay as crystobalite
is a
> destructive crystal that decreases durability and thermal shock
> resistance in the wares. He does go on to say that below 2200 F and
to
> about 1800 F, desirable crystals are forning, like mullite crystals
that
> give strength to high-fired clay and glazes and surface crystals
that
> give mattness and texture to the glaze. Are these the crystal
inclusions
> you reference? Are there pictures somewhere?
>
> thanks in advance for furthering my education.
>
> christy in connecticut, getting ready to 2 (count em 2) salt/soda
kiln
> workshops. cannot wait. throwing my little head off making pots to
go
> into these wonderful kilns.
>
> >
> >
> >>Ivor and Olive Lewis wrote:
> >>
> >>
> >>
> >>>Dear Friends,
> >>>I go along with Richard Aerni on this one.
> >>>Having a high thermal mass slows the cooling rate of the kiln and
> >>>allows time for crystal inclusions to nucleate and grow.
> >>>Helps to give pots "character
> >>>
> >>>
>
>
______________________________________________________________________
________
> 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.
| |
|
