Re: [Clayart] nomenclature

[Cynosure -Arts]

thx for all the responses, especially yeladon.

I recall reading somewhere that the yellow from refiring temmokus is from new iron silicate crystals.

Anyway, I have a test in the current firing that is an amalgam of Pinnell's Blue Celadon, adjusted according to Au with some Ti to turn it yellow (see his test on glazy.org), and then adjusted again per Feng with Strontium replacing the Barium. I'll post a pic if it turns out promising.

Doing some further research, there does appear to be an old Chinese glaze with similar properties to those I'm looking for, but the translation of the name comes out as 'chicken fat yellow.' Perhaps not the best branding nowadays. What do y'all think of Urochrome? That's the pigment that gives urine its yellow color - lol

And though I have seen numerous references when googling 'yellow celadon,' I still balk at using celadon to refer to anything besides grey/green/blue.

Eric Newman

________________________________
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Sent: Thursday, February 25, 2021 6:52 PM
To: cla...@lists.clayartworld.com <cla...@lists.clayartworld.com>
Subject: Clayart Digest, Vol 63, Issue 46

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Today's Topics:

1. Re: Nomenclature (ron...@ca.inter.net)
2. Re: "Poisonous raw material, not for dinnerware" (John Post)
3. Re: firing time and color (ron...@ca.inter.net)
4. Re: fast firing (ron...@ca.inter.net)
5. Re: "Poisonous raw material, not for dinnerware"
(vpit...@dtccom.net)
6. Re: fast firing (vpit...@dtccom.net)


----------------------------------------------------------------------

Message: 1
Date: Thu, 25 Feb 2021 16:24:04 -0500
From: ron...@ca.inter.net
To: Clayart international pottery discussion forum
<cla...@lists.clayartworld.com>, Dick Lumaghi
<dlum...@cybermesa.com>
Subject: Re: [Clayart] Nomenclature
Message-ID: <20210225162404....@webmail.ca.inter.net>
Content-Type: text/plain; charset=ISO-8859-1; DelSp="Yes";
format="flowed"

I had forgotten that I had refired, in a bisque firing, one of my
Tenmoku pieces and got a yellow - not a nice yellow by the way!

RR


Quoting Dick Lumaghi <dlum...@cybermesa.com>:

> One of my pottery teachers had a lovely classic cone 10 temmoku that
> when refired at bisque temperature, turned a bright yellow (from
> re-oxidation, I?d guess) but left the nice brown rim from the
> earlier firing?a very attractive combination. I wasn?t able to
> reproduce this myself, but you might give this a try.
>
> Dick Lumaghi
>
>
>
> Sent from my iPhone
>
>> On Feb 24, 2021, at 6:11 AM, vpit...@dtccom.net wrote:
>>
>> ?How about yeladon?
>> - Vince
>>
>> Vince Pitelka
>> Professor Emeritus of Art/Ceramics
>> Appalachian Center for Craft
>> School of Art, Craft & Design
>> Tennessee Tech University
>> Now Residing Chapel Hill, NC
>> vpit...@dtccom.net
>> www.vincepitelka.com<http://www.vincepitelka.com>
>>
>> -----Original Message-----
>> From: Clayart <clayart...@lists.clayartworld.com> On Behalf Of Cynosure
>> -Arts
>> Sent: Tuesday, February 23, 2021 10:41 PM
>> To: cla...@lists.clayartworld.com
>> Subject: Re: [Clayart] Nomenclature
>>
>> Hi all -
>>
>> I am trying to develop a transparent yellow cone 10 redux glaze, similar in
>> effect (darker when it pools) to a traditional celadon.
>> I hesitate to call it a yellow celadon, however, because it is not in the
>> traditional green/grey/blue hues of an iron-based true celadon.
>>
>> For the traditionalists here, is there a better yet still descriptive name,
>> or am I over-thinking this?
>>
>> Thx for your thoughts,
>> Eric Newman
>>
>> -------------- next part --------------
>> An HTML attachment was scrubbed...
>> URL:
>> <https://lists.clayartworld.com/pipermail/clayart/attachments/20210224/e73f1
>> a70/attachment.htm>
>>
>>
>>
>
>



Ron Roy
ron...@ca.inter.net
Web page ronroy.net




------------------------------

Message: 2
Date: Thu, 25 Feb 2021 14:35:07 -0700
From: John Post <johnp...@gmail.com>
To: Clayart international pottery discussion forum
<cla...@lists.clayartworld.com>
Subject: Re: [Clayart] "Poisonous raw material, not for dinnerware"
Message-ID:
<CANh2d729tRKNz0HPoQKPxee4...@mail.gmail.com>
Content-Type: text/plain; charset="UTF-8"

I think barium carbonate gets a bad rap as a glaze flux. The hazard
with barium is in the raw form. You should not ingest barium
carbonate because it is poisonous. When I mix glazes I wear a
respirator so there is no chance of me ingesting barium carbonate or
any other glaze material. I do not drink any of my glaze slurries so
there is no chance of me ingesting it while applying the glaze.

Once barium carbonate is fired in a well formulated glaze it is no
longer toxic as it is part of glaze.

The key part of this is that the barium needs to be part of a well
formulated glaze.

Matt Katz in his Ceramics Materials Workshop classes teaches about
what makes glazes stronger and more likely to survive the abuse of the
dishwasher. That is not the stated goal of his classes but in the
classes you learn about the Stull Chart and how to manipulate glazes
using it to get them to do what you want.

Matt often speaks of the .3 to .7 ratio of alkaline metals to alkaline
earths as being important for the development of durable glazes. If
you get too far away from that ratio, your glazes become less durable.
If you look at the flux ratios in older books for cone 04 recipes, you
will see that most of them are far away from this ideal ratio and that
is part of the reason why they fail so spectacularly.

People did all kinds of crazy stuff to get glazes to fire at lower and
lower temperatures in electric kilns. One of these was to add large
amounts of lithium carbonate to glazes. Lithium carbonate causes lots
of problems when added in large amounts and it certainly does not do
anything to help make a well formulated glaze at cone 04. If you look
at older books on cone 04 glazes they contain lots of recipes that do
not turn into stable glazes when fired.

One of the best glazes in terms of durability that Matt has ever
tested was a cone 04 glaze. The recipe is simple - 90% Frit 3124 and
10% EPK.

Matt has done lots of work developing durable glazes across a wide
range of temperatures. This led him to explore the effects of boron on
glaze durability. It turns out boron actually improves glaze
durability at the lower temperature range. As a rule of thumb, if you
wanted to increase glaze durability at cone 6 you would make sure your
glaze has about .15 boron in the UMF. To improve durability at cone 04
your glaze can use somewhere between .4 to .55 boron in the UMF. I am
not quoting Matt verbatim here, just tossing out some numbers I
remember from taking his two glaze classes.

Boron is the key to developing good functional glazes at temperatures
lower than cone 10. Building glazes using large amounts of lithium
carb or barium carb in order to fire at lower temperatures ends up
creating unstable glazes.

I am currently working on developing cone 10 glazes using that .3 to
.7 flux ratio. On the second image at this link you can see the color
response that resulted from substituting one alkaline earth for
another.
https://glazy.org/recipes/90747

If you are interested in taking Matt Katz's glaze courses you can find
information here - https://www.ceramicmaterialsworkshop.com/

John Post


------------------------------

Message: 3
Date: Thu, 25 Feb 2021 16:51:05 -0500
From: ron...@ca.inter.net
To: Clayart international pottery discussion forum
<cla...@lists.clayartworld.com>, mel jacobson <mel...@mail.com>
Cc: clay art <cla...@lists.clayartworld.com>
Subject: Re: [Clayart] firing time and color
Message-ID: <20210225165105....@webmail.ca.inter.net>
Content-Type: text/plain; charset=ISO-8859-1; DelSp="Yes";
format="flowed"

1700F is 926C so sodium and potassium (the main melters in clay
bodies)would still be active.

I have no idea how long it would take at that temperature to make up
for a bisque firing that was 50C short. If I had to guess it would
certainly be days if not weeks.

I hear some stories of some ceramic mixtures taking years to reach
equilibrium.

Equilibrium means the point at which all chemical and molecular
activity stops.

That means that none of our glazes and clays have reached that point.
The faster you fire the further you are from equilibrium.

I have been talking to Carol and she has gotten me re-interested in
the chemistry part - again. What an interesting subject ceramics is.

RR

Quoting mel jacobson <mel...@mail.com>:

> has anyone on clayart noticed that carol marians does magic every week?
> she changes blue to yellow, brown to green, green to red to ochre to black.
> her work is about firing length. yes, chemistry too, but she
> down-fires sometimes for
> 25 hours. everything changes. of course it does.
> why are we surprised.???? remember when we bisque fired bad copper
> red. turns to red.
> slow cool twice, and i have even done it three times. bright red..
>
> we hope you all respect what a gift carol has been to us.
> speed of firing, the cone you fire. how you cool, or control cool.
> it changes everything.
>
> i have even been down firing bisque. the spring loaded (automatic
> kiln) kiln i have at the farm often gets away from me.
> so, i fire down to 1700f and let it sit for an hour. or in some
> cases, back up to 1700 and hold.
> i cannot prove anything, but ron says it `should` compensate. hell
> i will try anything.
>
> i only fire to make `my` pots beautiful, what others get, is their
> business. it is up to you. and keep a passport handy.
> mel
>
>
> website: www.melpots.com<http://www.melpots.com>
> www.melpots.com/CLAYART.HTML<http://www.melpots.com/CLAYART.HTML>
>
>



Ron Roy
ron...@ca.inter.net
Web page ronroy.net




------------------------------

Message: 4
Date: Thu, 25 Feb 2021 17:13:11 -0500
From: ron...@ca.inter.net
To: Clayart international pottery discussion forum
<cla...@lists.clayartworld.com>, paul gerhold <gerho...@gmail.com>
Cc: Hank Murrow <hmu...@efn.org>, Clayart international pottery
discussion forum <cla...@lists.clayartworld.com>
Subject: Re: [Clayart] fast firing
Message-ID: <20210225171311....@webmail.ca.inter.net>
Content-Type: text/plain; charset=ISO-8859-1; DelSp="Yes";
format="flowed"

Hi Paul,

First - I think glazes have a range of maturity. What I consider
mature would depend on my sensibility.

I think what you are asking is unanswerable and to a large extent
dependent on the criteria applied.

What would be your definition?

I have the feeling that whatever you say a mature glaze is - somebody
will come up with an exception.

RR

Quoting paul gerhold <gerho...@gmail.com>:

> Hank,
> I don?t think I ever suggested that that downfiring and rate of
> downfiring will not affect results on crystal glazes. My question is
> about how rate of firing to a given cone affects the final result.
> As Carol so nicely showed difference does occur in saturated metal
> glazes.
>
> Still looking for a definition of what constitutes a ? matured
> glaze? other than it achieves the objective the potters set for a
> glaze.
>
> Paul
>
> Sent from my iPad
>
>> On Feb 25, 2021, at 7:14 AM, Hank Murrow <hmu...@efn.org> wrote:
>>
>> ?
>>
>>> On Feb 24, 2021, at 3:01 PM, paul gerhold <gerho...@gmail.com> wrote:
>>>
>>> I have a degree in Chemical Engineering which is irrelevant to my
>>> question on defining glaze maturation which so far nobody has
>>> given a science type answer. And of course every glaze performs
>>> differently at a specific cone. The question asked is there a
>>> significant difference in a glaze if it reached the same at
>>> different rates of firing?
>>
>> Dear Paul;
>>
>> Based upon my experiments with down-firing in oxidation, I see
>> large differences in appearance with as little as 2 to as much as 8
>> hours of this r?gime around 1850F. Most of my glazes are flux matts
>> or flux semi-matts, and they respond wondrously to this treatment,
>> which I discovered while trying to get increasingly red Shinos.
>> Holding glass brought to maturation under mostly reduction
>> conditions, seems optimum for fully melting them, but holding at a
>> moment of crystallization during the cooling seems to deepen the
>> color response. I find that bigger changes in color and surface
>> result from this regime than from holding at higher temps, and
>> eliminates the chance of overfiring at the same time.
>>
>> Cheers, Hank Murrow
>



Ron Roy
ron...@ca.inter.net
Web page ronroy.net




------------------------------

Message: 5
Date: Thu, 25 Feb 2021 18:37:59 -0500
From: <vpit...@dtccom.net>
To: "'Clayart international pottery discussion forum'"
<cla...@lists.clayartworld.com>
Subject: Re: [Clayart] "Poisonous raw material, not for dinnerware"
Message-ID: <002201d70bcf$41466ff0$c3d34fd0$@dtccom.net>
Content-Type: text/plain; charset="utf-8"

Hi John -
I agree completely, and thanks for posting that. We never abandoned barium carbonate in the glaze lab at the Appalachian Center for Craft. We used it wisely in highfire glazes, and there is nothing else that would give the beautiful semi-matt glazes we got with a little barium.

As you saw, the glaze I was referring to was a cone-04 matt blue-purple that contained 45% barium plus significant copper and lithium. It was highly unstable.
- Vince

Vince Pitelka
Professor Emeritus of Art/Ceramics
Appalachian Center for Craft
School of Art, Craft & Design
Tennessee Tech University
Now Residing Chapel Hill, NC
vpit...@dtccom.net
www.vincepitelka.com<http://www.vincepitelka.com>

-----Original Message-----
From: Clayart <clayart...@lists.clayartworld.com> On Behalf Of John Post
Sent: Thursday, February 25, 2021 4:35 PM
To: Clayart international pottery discussion forum <cla...@lists.clayartworld.com>
Subject: Re: [Clayart] "Poisonous raw material, not for dinnerware"

I think barium carbonate gets a bad rap as a glaze flux. The hazard with barium is in the raw form. You should not ingest barium carbonate because it is poisonous. When I mix glazes I wear a respirator so there is no chance of me ingesting barium carbonate or any other glaze material. I do not drink any of my glaze slurries so there is no chance of me ingesting it while applying the glaze.

Once barium carbonate is fired in a well formulated glaze it is no longer toxic as it is part of glaze.

The key part of this is that the barium needs to be part of a well formulated glaze.

Matt Katz in his Ceramics Materials Workshop classes teaches about what makes glazes stronger and more likely to survive the abuse of the dishwasher. That is not the stated goal of his classes but in the classes you learn about the Stull Chart and how to manipulate glazes using it to get them to do what you want.

Matt often speaks of the .3 to .7 ratio of alkaline metals to alkaline earths as being important for the development of durable glazes. If you get too far away from that ratio, your glazes become less durable.
If you look at the flux ratios in older books for cone 04 recipes, you will see that most of them are far away from this ideal ratio and that is part of the reason why they fail so spectacularly.

People did all kinds of crazy stuff to get glazes to fire at lower and lower temperatures in electric kilns. One of these was to add large amounts of lithium carbonate to glazes. Lithium carbonate causes lots of problems when added in large amounts and it certainly does not do anything to help make a well formulated glaze at cone 04. If you look at older books on cone 04 glazes they contain lots of recipes that do not turn into stable glazes when fired.

One of the best glazes in terms of durability that Matt has ever tested was a cone 04 glaze. The recipe is simple - 90% Frit 3124 and 10% EPK.

Matt has done lots of work developing durable glazes across a wide range of temperatures. This led him to explore the effects of boron on glaze durability. It turns out boron actually improves glaze durability at the lower temperature range. As a rule of thumb, if you wanted to increase glaze durability at cone 6 you would make sure your glaze has about .15 boron in the UMF. To improve durability at cone 04 your glaze can use somewhere between .4 to .55 boron in the UMF. I am not quoting Matt verbatim here, just tossing out some numbers I remember from taking his two glaze classes.

Boron is the key to developing good functional glazes at temperatures lower than cone 10. Building glazes using large amounts of lithium carb or barium carb in order to fire at lower temperatures ends up creating unstable glazes.

I am currently working on developing cone 10 glazes using that .3 to
.7 flux ratio. On the second image at this link you can see the color response that resulted from substituting one alkaline earth for another.
https://glazy.org/recipes/90747

If you are interested in taking Matt Katz's glaze courses you can find information here - https://www.ceramicmaterialsworkshop.com/

John Post




------------------------------

Message: 6
Date: Thu, 25 Feb 2021 18:46:59 -0500
From: <vpit...@dtccom.net>
To: "'Clayart international pottery discussion forum'"
<cla...@lists.clayartworld.com>
Subject: Re: [Clayart] fast firing
Message-ID: <002901d70bd0$82d0bce0$887236a0$@dtccom.net>
Content-Type: text/plain; charset="utf-8"

Hi Paul -
Sometimes you are just in a contentious mood. When I say "obvious to most people," it should go without saying that it is obvious based on long experience and experimental data. That's what it means. And science comes from experience and experimental data. That's all the historic potters had before modern ceramic science, and look at the results they got from long experience and experimental data.
- Vince

Vince Pitelka
Professor Emeritus of Art/Ceramics
Appalachian Center for Craft
School of Art, Craft & Design
Tennessee Tech University
Now Residing Chapel Hill, NC
vpit...@dtccom.net
www.vincepitelka.com<http://www.vincepitelka.com>

-----Original Message-----
From: Clayart <clayart...@lists.clayartworld.com> On Behalf Of paul gerhold
Sent: Thursday, February 25, 2021 1:23 PM
To: Clayart international pottery discussion forum <cla...@lists.clayartworld.com>
Subject: Re: [Clayart] fast firing

Yes and I remember when spraying water on hot Raku pieces was supposed to preserve the black. You of all people should know that ? obvious to so many people ? is not a substitute for science or experimental data. Or when putting a lemon slice on a glaze was proof the glaze was food safe.

And still no answer as to what ? maturity ? actually means relative to glaze firings.

Paul

Sent from my iPad

> On Feb 25, 2021, at 1:13 PM, vpit...@dtccom.net wrote:
>
> ?Hi Paul -
> I appreciate you seeking a scientific answer. That's fine just as a matter of personal curiosity. But you don't really need a scientific answer when the difference in results is so obvious to so many people.
> - Vince
>
> Vince Pitelka
> Professor Emeritus of Art/Ceramics
> Appalachian Center for Craft
> School of Art, Craft & Design
> Tennessee Tech University
> Now Residing Chapel Hill, NC
> vpit...@dtccom.net
> www.vincepitelka.com<http://www.vincepitelka.com>
>
> -----Original Message-----
> From: Clayart <clayart...@lists.clayartworld.com> On Behalf Of
> paul gerhold
> Sent: Wednesday, February 24, 2021 6:01 PM
> To: Clayart international pottery discussion forum
> <cla...@lists.clayartworld.com>
> Subject: Re: [Clayart] fast firing
>
> I have a degree in Chemical Engineering which is irrelevant to my question on defining glaze maturation which so far nobody has given a science type answer. And of course every glaze performs differently at a specific cone. The question asked is there a significant difference in a glaze if it reached the same at different rates of firing?
>
> Sent from my iPad
>
>> On Feb 24, 2021, at 3:29 PM, Robert Harris <robert...@gmail.com> wrote:
>>
>> ?Paul, think like a chemist! This one is easy. Reaction kinetics.
>> This is a pretty good example of thermodynamic versus kinetic equilibrium.
>> You are assuming that silica glass melting/mixing/reaction is
>> identical across glaze recipes and (and cone recipes) such that
>> temperature can be linearly substituted with time. In other words, a
>> cone recipe has a particular relationship between time and
>> temperature, increase the time and you substitute for temperature.
>> However, not all glazes will show the same substitution. Also, higher
>> temperatures will affect viscosity and boiling point in a way that is not substitutable for time.
>> In terms of observed experience, those glazes that are very well
>> melted at higher the top of their cone range, and have a wide range
>> of acceptable temperatures, are unlikely to have much visual difference.
>> I bet that other measures such as clay/glaze bonding, durability etc
>> show more of a difference.
>>
>>>> On Wed, 24 Feb 2021 at 08:30, paul gerhold <gerho...@gmail.com> wrote:
>>>
>>> Maybe the issue is the definition of glaze maturation. My guess is
>>> it only means the glaze satisfy the potters goals for the glaze.
>>>
>>> Personally I cannot sayI have ever seen any difference in my glazes
>>> whether I get to the cone slowly or rapidly. My assumption would be
>>> the only way it would make any difference is if there is a significant lag time
>>> for the energy in the kiln to transfer into the glaze. I wonder if anyone
>>> has any actual evidence of difference.
>>>
>>> Paul
>>>
>>> Sent from my iPad
>>>
>>>>> On Feb 23, 2021, at 4:13 PM, vpit...@dtccom.net wrote:
>>>>
>>>> ?Hi Paul -
>>>> This has been pretty thoroughly discussed many times on Clayart.
>>> Initially, you can increase temperature very quickly, but it is
>>> natural that a kiln will slow down as it approaches maturation
>>> temperature, and that gives time for heatwork to do its job on the
>>> glazes. If you fire right up to intended maturation temperature
>>> according to a cone or the setting on a programmable kiln and then
>>> hold for a period of time to mature the glazes, you will be
>>> overfiring. Maturation is a result of both temperature and duration.
>>> If you slow down the firing at the end as you work up to maturation
>>> temperature, you can hit the cone dead-on while also having allowed
>>> the glazes to mature. That said, if you did some experimentation,
>>> fast-firing to a maturation temperature perhaps a cone lower than
>>> what you intend, and then holding the temperature for a period of time, you could probably get the same results, but why do that?
>>>> - Vince
>>>>
>>>> Vince Pitelka
>>>> Professor Emeritus of Art/Ceramics
>>>> Appalachian Center for Craft
>>>> School of Art, Craft & Design
>>>> Tennessee Tech University
>>>> Now Residing Chapel Hill, NC
>>>> vpit...@dtccom.net
>>>> www.vincepitelka.com<http://www.vincepitelka.com>
>>>>
>>>> -----Original Message-----
>>>> From: Clayart <clayart...@lists.clayartworld.com> On Behalf Of
>>> paul gerhold
>>>> Sent: Tuesday, February 23, 2021 12:19 PM
>>>> To: Clayart international pottery discussion forum <
>>> cla...@lists.clayartworld.com>
>>>> Subject: Re: [Clayart] fast firing
>>>>
>>>> Vince,
>>>> I do not understand how glaze maturation can change from fast to
>>>> slow
>>> firing if you are firing to the same cone. Obviously if you are
>>> firing to the same end temp. Getting there slower will increase the
>>> heat work, as will holding at peak temp.
>>>>
>>>> Paul
>>>>
>>>> Sent from my iPad
>>>>
>>>>> On Feb 22, 2021, at 9:39 PM, vpit...@dtccom.net wrote:
>>>>>
>>>>> ?The main thing that suffers in excessively-fast glaze firings is
>>>>> glaze
>>> maturation. When I was making kitchenware and tableware full-time
>>> in Northern California 1975-85, I built a 100-cubic-foot natural
>>> gas, natural draft downdraft car kiln. The decoration was mostly
>>> oxide brushwork, slip decoration, and impressed decoration with a
>>> few transparent glazes and simple colored glazes, rather than the
>>> subtleties of glaze outcome. I did want even reduction, but never
>>> had trouble achieving that. You can see the kiln and the wares in
>>> the Railroad Stoneware section of the gallery on my website if you
>>> care to. When I was rushed, as it seems I always was before our big
>>> annual studio sale in early December, I would fire that
>>> 100-cubic-foot kiln on an 18-hour cycle - seven hours from cold to
>>> cone-10, seven hours to cool, and four hours to unload and reload.
>>> The time of day would cease to matter, and I'd do four or five
>>> firings in sequence on that 18-hour schedule to get ready for the studio sale, fitting in a little sleep here and there as I was able. I was happy with the results.
>>>>>
>>>>> Periodically during my years at the Appalachian Center for Craft,
>>>>> I'd
>>> have a student proudly proclaim that they had fired our
>>> 40-cubic-foot downdraft kiln from cold to cone-10 in four hours.
>>> Yeah, they did, but the results were almost always lackluster. In
>>> any firing, the hotter the kiln gets, the more BTUs it takes to advance it further.
>>> So, if you keep the heat settings constant in the latter part of the
>>> firing, temperature rises slows down, and heatwork has time to
>>> mature the glazes. In contrast, if you keep cranking up the BTUs in
>>> the latter part of the firing to get done in a hurry, the
>>> temperature zooms ahead of maturation, and you end up with a lot of dead, lifeless glazes.
>>>>>
>>>>> In some tile factories, the tiles moving through giant
>>>>> rolling-hearth
>>> kilns pass from room temperature to cone-10 and back to room
>>> temperature in as little as thirty minutes.
>>>>> - Vince
>>>>>
>>>>> Vince Pitelka
>>>>> Professor Emeritus of Art/Ceramics Appalachian Center for Craft
>>>>> School of Art, Craft & Design Tennessee Tech University Now
>>>>> Residing Chapel Hill, NC vpit...@dtccom.net www.vincepitelka.com<http://www.vincepitelka.com>
>>>>>
>>>>> -----Original Message-----
>>>>> From: Clayart <clayart...@lists.clayartworld.com> On Behalf
>>>>> Of Daphne Vega
>>>>> Sent: Monday, February 22, 2021 5:56 PM
>>>>> To: Clayart international pottery discussion forum
>>>>> <cla...@lists.clayartworld.com>
>>>>> Subject: Re: [Clayart] fast firing
>>>>>
>>>>> Hi Mel
>>>>> I?m curious, when glaze firing, what is ?too fast?? Is it even a
>>> problem at all if the emphasis is on the slow cool down, and
>>> reducing on the cool down?
>>>>> You know (as I posted here a few times) I was struggling with
>>>>> evening
>>> out my kiln in 18/19, firing it over and over with nothing but
>>> bricks inside to experiment with different modifications to the control.
>>> Well I learned how to drive it pretty well and then the last 2
>>> firings last year (moved studio and haven?t fired in it since) I
>>> realized it was moving so fast that I was going to potentially get
>>> it to cone 6 in under 4 hours. I got nervous so I slowed it down to
>>> stretch the firing out a bit longer, because it was filled with
>>> pieces I could not afford to lose and I did not know what I would get with such a different fire schedule.
>>>>> I remrmber in college being told that there was definitely a too
>>>>> fast,
>>> but I didn?t question how or why then.
>>>>> I know the best answer is to test myself ;)
>>>>>
>>>>> Still, I?d love to hear others thoughts and experiences
>>>>>
>>>>> Thanks.
>>>>> Daphne
>>>>>
>>>>> Autocorrect may win the battle but not the where.
>>>>>
>>>>>>> On Feb 22, 2021, at 1:02 PM, mel jacobson <mel...@mail.com> wrote:
>>>>>>
>>>>>> ?since i do it all the time, some observations.
>>>>>> i took the controller off my small kiln.
>>>>>> i use a tested and trusted clay and glaze.
>>>>>> i down fire after shutting off the kiln.
>>>>>> my gas kilns are all manual. they fire like rocket ships.
>>>>>>
>>>>>> kiln controllers for most of you are miracles. busy schedule,
>>>>>> fire while at the movie, fire with your smart phone..nice. but
>>>>>> the programs are made by others, for a broad range of people firing.
>>>>>> so,
>>> one size fits all.
>>>>>> and for many, re/program is not easy. and i hate the kiln
>>>>>> shutting
>>> down at 2000 with a note:
>>>>>> "you are a naughty potter, ach tung, start again." "heilorton"
>>>>>>
>>>>>> i do not live in that camp. size 32 shorts do not fit me.
>>>>>> i will make up my own mind thank you. and, i never leave my
>>>>>> kilns
>>> while firing.
>>>>>>
>>>>>> bill schran when making crystals needs the controller and controls it.
>>> it is a god send.
>>>>>> but i have a nice controller on my big electric, it is great for
>>> bisque. slow mode.
>>>>>> rarely glaze fire in it. Colleen fired about 60 mugs last week
>>>>>> in the big kiln to cone 7. fired great. because of -30 in the
>>>>>> kiln room, she unhooked the controller, and plugged the kiln
>>>>>> directly into
>>> the wall outlet. fired with the kiln sitter. you see, dual system.
>>>>>>
>>>>>> i bisque fire very slow, and allow gobs of time for the clay to
>>>>>> expel all gases. and, some commercial bodies always bloat if not
>>>>>> slow bisque fired. lots of crap in that clay.
>>>>>>
>>>>>> but, if you have a controller and love it, yes by all means enjoy
>>>>>> it and be thankful for it. it is yours, learn to control it however.
>>>>>> mel
>>>>>>
>>>>>>
>>>>>>
>>>>>> website: www.melpots.com<http://www.melpots.com>
>>>>>> www.melpots.com/CLAYART.HTML<http://www.melpots.com/CLAYART.HTML>
>>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>
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[sumi]

On 2/25/21 9:35 PM, Cynosure -Arts wrote:
> I still balk at using celadon to refer to anything besides grey/green/blue.

I agree. And yet commercial glaze manufactures have totally taken over
that term to mean any translucent glaze, so young potters simply assume
that is what celadon means.

Sumi

[Ric Swenson]

Sumi and friends on clayart.

According to lore....In the strict sense...CELADON GLAZE first appeared in the areas around LongQuan, China, some 2,500 years ago. Geographically, LongQuan is a stone's throw from HangZhou, in southeast China. The clay body, which contains some iron, led to a clear glaze which had a tinge of pale green/blue upon firing. This led, in turn for local potters to add some iron oxide materials that cast the green to darker shades including an "olive green".

Western, particularly French language speakers, much later, admired the exported green glaze, emulated it and gave it the name Celadon. The name, by the way, comes from a character in a French play, named Celadon who always appeared in a green cloak on stage. The name stuck and since has been used to describe light pale green, and even pale blue/gray glazes and even olive green shades.

LongQuan ( pronounced "lung chuan" ) today is still a small city and most famous for celadon glazes. Nearly all pottery shops in LongQuan feature celadon green glaze. I attended the opening of the new Ceramics Museum with my good friend Professor Jin Wen Wei in the city in 2009. He was born near LongQuan, maintains a studio there and also in JingdeZhen (about 5 hours drive away) where he teaches at his alma mater: The JingdeZhen Ceramic University. (30,000+ students and nearly 3,000 faculty ). My wife, Xu Guan Hua, has taught art history and design theory there, since 2005. She is one of the few professors at the U. that can teach in Mandarin and English. Maybe the only one?

Driving to remote LongQuan from JingdeZhen one passes through 81 tunnels ! The area is very mountainous. Some tunnels are a few meters and some are very long. I counted them on my first drive there. The longest is about 1.5 km. There is no air service or train to LongQuan or even a train. Car or bus is the only choice. There is no road directly from LongQuan to HangZhou, which is physically quite close but blocked by mountainous terrain.

In 2010, during the summer break from teaching at JingdeZhen Ceramic U. ( 2006-2018) I was invited to spend a few weeks teaching at the small college in LongQuan. I had 33 beginner potters to teach throwing. It was part of an employment training class sponsored by the government of the province, for young adults wishing to find jobs at local potteries. It was a great experience. As a side note, on a subsequent trip to LongQuan, I was approached by a young man who was very excited to see me and tell me he had landed a job in a shop as a thrower. He was very grateful for the class.

Chinese television covered the provincial governor's visit to our class and I taught him to knead clay, on camera...he, in his very expensive looking business suit...and an apron !

LongQuan is also very famous for sword-making and has a very long history there. Iron deposits in the local mountains make sword-making and celadon glazes possible. All manner of swords, daggers and knives are available and one can hear hammering of steel all over the city. They make Chinese and Japanese style swords and have exported worldwide. My collection includes 2 very fine examples: a Chinese traditional straight one and a Samurai style curved sword.

The style of forms and shapes varies widely but the glaze in LongQuan is celadon. Traditional shapes and more contemporary forms abound.

Most wares are now gas fired in fiber lined kilns but I was honored on one visit to help stoke a very long climbing "dragon kiln" in LongQuan.

Good memories.

Regards,

Ric, from retirement at age 73, here in JingdeZhen.

Stay safe...mask up !

________________________________
From: Clayart <clayart...@lists.clayartworld.com> on behalf of sumi <su...@herwheel.com>
Sent: Saturday, February 27, 2021 12:14 AM
To: cla...@lists.clayartworld.com <cla...@lists.clayartworld.com>
Subject: Re: [Clayart] nomenclature

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[Terrance Lazaroff]

Hi Ric;

Well appreciated. Thank you.

Terry

Sent from my iPad

> On Feb 26, 2021, at 6:39 PM, Ric Swenson <RicSwen...@hotmail.com> wrote:
>
> Sumi and friends on clayart.

[Edouard Bastarache]

WTG,
Good retirement

Edouard.





-----Message d'origine-----
De : Clayart [mailto:clayart...@lists.clayartworld.com] De la part de
Ric Swenson
Envoyé : 26 février 2021 17:51
À : Clayart international pottery discussion forum
Objet : Re: [Clayart] nomenclature

[vpit...@dtccom.net]

Hi Ric. Thanks very much for that delightful narration!

- Vince

Vince Pitelka
Professor Emeritus of Art/Ceramics
Appalachian Center for Craft
School of Art, Craft & Design
Tennessee Tech University
Now Residing Chapel Hill, NC
vpit...@dtccom.net
www.vincepitelka.com

-----Original Message-----
From: Clayart <clayart...@lists.clayartworld.com> On Behalf Of Ric
Swenson
Sent: Friday, February 26, 2021 5:51 PM
To: Clayart international pottery discussion forum