Hank Murrow on thu 31 may 07
On May 31, 2007, at 2:22 PM, Dawn Raburn wrote:
> Have been reading up on firing shinos and it seems that a long
> oxidation soak cool helps. My question is what does this do to other
> glazes? I want to also fire celadons, ash, and kaki etc. Will the
> ox. soak affect these glazes and if so, how?
Dear Dawn;
I assume that from the glazes you favor that you fire at cone 9 and
above. The soak in oxidation around 1900F will not likely benefit
your shiny glazes, except possible matting the surface somewhat. The
glazes that will be improved most will be those that are slightly to
very loaded with flux and/or alumina. Such glazes develop very small
micro-crystals that orgasnize the coloring oxides at the surface of
the glaze where they can be re-oxidized during the soak. I get quite
incredible shinos without any soda ash at all.
You can visit an article I wrote for CM here: http://
www.ceramicsmonthly.org/mustreads/shinofire.asp
Cheers, Hank
www.murrow.biz/hank
Dawn Raburn on thu 31 may 07
Have been reading up on firing shinos and it seems that a long
oxidation soak cool helps. My question is what does this do to other
glazes? I want to also fire celadons, ash, and kaki etc. Will the
ox. soak affect these glazes and if so, how?
Thanks,
Dawn
Lesley Anton on thu 31 may 07
Hi Dawn,
I just had this very same issue come up about a month ago and some
fine folks here at Clayart forwarded me some great articles. I have
to go back and find them, but basically, you will get great results
from soaking and slow cooling shinos. The other glaze subject is
tenuous though. I make ceramic and wood lamps that retail for about
1200. - I have to refire sometimes because the lamps are big and I
hate to loose them if I can fix 'em.
I have had mixed results -
Celedons - once on a very slow cool - 13 hrs from 2000 down to 1500
degrees - it turned out fine - nice and clear.
The second slow cool - I was also firing a matte butter
glaze which needs a super slow cool - I got complete matte celedon.
Cloudy and Yuk!! The weirdest thing on that firing was ....I went to
re-fire the pots that went cloudy,,,I went to pick up my kids from
gymnastics and had my husband do the reduction over the phone (not a
potter) and when I came back about an hour and a half later, the
damper was way open, no flame, temp had shot up to 2200 while I was
gone .....AND, my cone pack fell over so I couldn't tell anything. I
freaked out and closed the damper a bunch so there was a little
backdraft of flame pillowing out one of the burner holes at the
bottom....did this for about 30 minutes- but i don't think the temp
even really reached cone 4 or 5. So then I turned off everything
when the temp read about 2350 - and quick cooled it. When I opened
up the door the next morning, the lamps were amazing. Clear and
beautiful - no matte, no cloudy surface.
So - very weird - celedons are sort of inconsistant I'd say with
regard to slow cooling
Copper Red did great
Temoku was very interesting. Lots of the rust and a really rich surface.
The Matte glazes are super beautiful - very matte! and they break
beautifully.
I mainly did held the temp at cone 10 for about an hour, then slowly
turned the gas down to about 1 1/2", leaving the damper the same.
This is usually happening around 1am - since I never seem to time
things right...so I go to sleep, then wake up around 7 and it is
usually around 1600 or 1700 degrees, so then I turn the gas down a
little more until it slowly goes thru 1500, then I shut everything down.
here's an article Hank Murrow forwarded me:
www.ceramicsmonthly.org/mustreads/shinofire.asp
Best of luck.
Lesley Anton
Lesley Anton
Owner, designer, potter
Lesley Anton Handmade Ceramic Lighting
323.934.3463
lesleyanton@mac.com
www.lesleyanton.com
Ian Currie on fri 1 jun 07
>> From: Dawn Raburn
>>
>> Have been reading up on firing shinos and it seems that a long
>> oxidation soak cool helps. My question is what does this do to other
>> glazes? I want to also fire celadons, ash, and kaki etc. Will the
>> ox. soak affect these glazes and if so, how?
Hi Dawn
You may well have lots of good advice on this already... I get my
Clayart as the digest, so a day later than some... but for what it's
worth:
A long cooling soak can have a dramatic effect on anything involving
crystals. This will certainly affect your shino, especially the red
"fire colour", and also your kaki, and probably your ash glazes too.
Basically the slow cooling will grow the crystals so that
- an otherwise clear glaze might show some crystals
- an otherwise shiny glaze might become matt
- otherwise small crystals might become large
There are many "well balanced" (usually shiny) glazes that will not
form crystals.
The long soak whether in cooling or at top temperature will also
promote the formation of the clay-glaze interface where the two
mingle. This will tend to increase the contrast between thick and
thin glaze as shows dramatically in "colour-break" glazes... glazes
that break to a different colour with different thickness. This may
affect your ash glaze.
If you wish to be sure I see your posting, please Cc me a copy
Thanks.... Ian
By the way, you can still purchase my glaze books at my website.
Ian Currie
"Mandala"
831 North Branch Road
Maryvale, Q. 4370
Australia
Ph: +61 7 4666 1237
http://ian.currie.to/
Larry Kruzan on fri 1 jun 07
I'm no expert on firing, learn new things every time, but aren't quick
cooling cycles best for glossy finishes? Seems like John H. explored this
pretty thoroughly at NCECA a couple years back and I think he has his
presentation posted on his website. Of course, celedons are a study all by
themselves!
Larry Kruzan
Lost Creek Pottery
www.lostcreekpottery.com
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Lesley Anton
Sent: Thursday, May 31, 2007 6:49 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: [CLAYART] firing shinos
when the temp read about 2350 - and quick cooled it. When I opened
up the door the next morning, the lamps were amazing. Clear and
beautiful - no matte, no cloudy surface.
So - very weird - celedons are sort of inconsistant I'd say with
regard to slow cooling
Copper Red did great
Temoku was very interesting. Lots of the rust and a really rich surface.
The Matte glazes are super beautiful - very matte! and they break
beautifully.
Lee Love on fri 1 jun 07
Dawn,
Look at John Britt's book on glazes. He offers different firing
schedules.
I have found, that There are different kinds of shinos and they
all like different firing schedules. I believe the cool down and
hold schedules are most important for fiber kilns that cool quickly.
--
Lee in Mashiko, Japan
Minneapolis, Minnesota USA
http://mashikopots.blogspot.com/
"To affect the quality of the day, that is the highest of arts." -
Henry David Thoreau
"Let the beauty we love be what we do." - Rumi
Hank Murrow on mon 4 jun 07
On May 31, 2007, at 9:56 PM, Ian Currie wrote:
> The long soak whether in cooling or at top temperature will also
> promote the formation of the clay-glaze interface where the two
> mingle. This will tend to increase the contrast between thick and
> thin glaze as shows dramatically in "colour-break" glazes... glazes
> that break to a different colour with different thickness. This may
> affect your ash glaze.
Part of another lovely & lucid post from Ian Currie..............
beautiful!
Cheers, Hank
www.murrow.biz/hank
Hank Murrow on mon 4 jun 07
On Jun 1, 2007, at 5:21 AM, Larry Kruzan wrote:
> I'm no expert on firing, learn new things every time, but aren't quick
> cooling cycles best for glossy finishes? Seems like John H.
> explored this
> pretty thoroughly at NCECA a couple years back and I think he has his
> presentation posted on his website. Of course, celedons are a study
> all by
> themselves!
Dear Larry;
Yes, quick cooling is better for glossy surfaces......... that is why
obsidian is a glassy rock. However, many of the finest Celadons from
China were cooled slowly enough to develop satiny surfaces. Those who
do not fire in very large(slow cooling) kilns can take advantage of a
soak either in reduction or oxidation around 1900F to develop such
surfaces and colors.
Cheers, Hank
www.murrow.biz/hank
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