Paul Haigh on wed 15 sep 10
In my latest wood firing, my celadons look pretty lack luster. In the last =
firing they had a nice green on thicker parts, speckled on stoneware, and a=
cool ice green on porcelain. This firing was hotter. It's not washed out d=
ue to ash- even some of the protected pieces are more gray and less green.
It's a custer/silica/whiting/ball clay/ 2% iron glaze. I don't have the rec=
ipe in front of me, but suffice to say- it was good in the last fire, not i=
n this one. The latest firing was hotter- cone 12 well down all around. I h=
ad more coal bed at the end of the firing, so I may not have had an oxidati=
on period right at the end of the firing, which I normally have- might that=
be the issue? Celadon normally wants reduction, correct?
Paul Haigh
Wiley Hill Mudworks
Web: http://wileyhill.com
Facebook: http://tinyurl.com/28ggv3w
etsy: http://www.etsy.com/shop/WileyHillMudworks
Eva Gallagher on wed 15 sep 10
I had 4 bowls in my last wood firing (actually just my second) in my train
kiln and one of the bowls was right on the bottom shelf and the other 3 on
the middle shelf. They were all glazed the same with a revised fraser
celadon. The bottom bowl was washed out while the ones on the middle shelf
were an acceptable blue green. Generally from examing other pots that were
on the bottom shelves - all were less reduced then higher up so in this cas=
e
I would have to say not enough reduction. I think John Britt in his book
mentions heavy reduction all the way through for celadons. In our gas kiln
we reduce from 012 and then medium redux unitl cone 8 when we reoxidize
unitl cone 10 is down and the celadons there are not too bad.
I found it hard to estimate how much reduction when firing the wood kiln.
Eva Gallagher
http://newfoundoutpotter.blogspot.com/
http://www.valleyartisans.com/gallagher/Gallagher.htm
----- Original Message -----
From: "Paul Haigh"
To:
Sent: Wednesday, September 15, 2010 10:12 AM
Subject: Celadon is washed out
> In my latest wood firing, my celadons look pretty lack luster. In the las=
t
> firing they had a nice green on thicker parts, speckled on stoneware, and
> a cool ice green on porcelain. This firing was hotter. It's not washed ou=
t
> due to ash- even some of the protected pieces are more gray and less
> green.
>
> It's a custer/silica/whiting/ball clay/ 2% iron glaze. I don't have the
> recipe in front of me, but suffice to say- it was good in the last fire,
> not in this one. The latest firing was hotter- cone 12 well down all
> around. I had more coal bed at the end of the firing, so I may not have
> had an oxidation period right at the end of the firing, which I normally
> have- might that be the issue? Celadon normally wants reduction, correct?
>
>
> Paul Haigh
> Wiley Hill Mudworks
> Web: http://wileyhill.com
> Facebook: http://tinyurl.com/28ggv3w
> etsy: http://www.etsy.com/shop/WileyHillMudworks
>
>
Paul Haigh on wed 15 sep 10
Thanks for the reply, but this is a stiff glaze- no movement from the dip l=
ine on these pieces (especially the sheltered ones) or thickening to show t=
hat they thinned on top- so I don't think that was the case. I'll look to m=
ake sure I didn't apply thinner, but I don't think so. I suspect some oxida=
tion/reduction issue, but am not sure
----- Original Message -----
From: "William & Susan Schran User"
To: wileyhill@COMCAST.NET, Clayart@LSV.CERAMICS.ORG
Sent: Wednesday, September 15, 2010 4:08:16 PM
Subject: Re: Celadon is washed out
On 9/15/10 10:12 AM, "Paul Haigh" wrote:
> It's a custer/silica/whiting/ball clay/ 2% iron glaze. I don't have the r=
ecipe
> in front of me, but suffice to say- it was good in the last fire, not in =
this
> one. The latest firing was hotter- cone 12 well down all around. I had mo=
re
> coal bed at the end of the firing, so I may not have had an oxidation per=
iod
> right at the end of the firing, which I normally have- might that be the
> issue? Celadon normally wants reduction, correct?
I suspect hotter temperature resulted in more melting of the glaze, resulte=
d
in thinner areas of glaze, especially on more vertical areas of pots, and
this resulted in less of your green color. Celadons are transparent glazes
with green/grey/blue colors and seem to have better/deeper color when a bit
thicker - at least this has been my experience...
Bill
--
William "Bill" Schran
wschran@cox.net
wschran@nvcc.edu
http://www.creativecreekartisans.com
Hank Murrow on wed 15 sep 10
On Sep 15, 2010, at 7:12 AM, Paul Haigh wrote:
> In my latest wood firing, my celadons look pretty lack luster. In the =3D
last firing they had a nice green on thicker parts, speckled on =3D
stoneware, and a cool ice green on porcelain. This firing was hotter. =3D
It's not washed out due to ash- even some of the protected pieces are =3D
more gray and less green.
>=3D20
> It's a custer/silica/whiting/ball clay/ 2% iron glaze. I don't have =3D
the recipe in front of me, but suffice to say- it was good in the last =3D
fire, not in this one. The latest firing was hotter- cone 12 well down =3D
all around. I had more coal bed at the end of the firing, so I may not =3D
have had an oxidation period right at the end of the firing, which I =3D
normally have- might that be the issue? Celadon normally wants =3D
reduction, correct?
Dear Paul;
Bluish celadons don't respond well to over-firing. They like to retain =3D
trapped gas bubbles to create that lovely blue color that I so love. =3D
They also hate titanium(in both body and glaze), which turns them green. =
=3D
Hope you figure it out and tell us what the trouble was.
Cheers, Hank=3D
William & Susan Schran User on wed 15 sep 10
On 9/15/10 10:12 AM, "Paul Haigh" wrote:
> It's a custer/silica/whiting/ball clay/ 2% iron glaze. I don't have the r=
ecipe
> in front of me, but suffice to say- it was good in the last fire, not in =
this
> one. The latest firing was hotter- cone 12 well down all around. I had mo=
re
> coal bed at the end of the firing, so I may not have had an oxidation per=
iod
> right at the end of the firing, which I normally have- might that be the
> issue? Celadon normally wants reduction, correct?
I suspect hotter temperature resulted in more melting of the glaze, resulte=
d
in thinner areas of glaze, especially on more vertical areas of pots, and
this resulted in less of your green color. Celadons are transparent glazes
with green/grey/blue colors and seem to have better/deeper color when a bit
thicker - at least this has been my experience...
Bill
--
William "Bill" Schran
wschran@cox.net
wschran@nvcc.edu
http://www.creativecreekartisans.com
David Finkelnburg on thu 16 sep 10
Paul,
You are absolutely right that a celadon requires reduction. The
reduction must occur when the iron can be reached by the kiln gases, though=
,
which means before the glaze melts.
Oxidation at the end of the your firing is not going to cause a
translucent glaze to appear more translucent. The oxidation will affect onl=
y
the glaze surface. The color is from reduced iron in the glass and you mos=
t
likely got dilution of the iron by dissolving more clay body in the hotter
firing, OR failed to get the iron reduced the same as in your previous
firing before the glaze melted and sealed over, OR both.
2% is about double the iron of most celadons so you should see plenty o=
f
color.
I hope this helps give you something more to consider when testing your
glaze further.
Dave Finkelnburg
http://www.mattanddavesclays.com
-----------------------------
Date: Wed, 15 Sep 2010 14:12:38 +0000
From: Paul Haigh
Subject: Celadon is washed out
In my latest wood firing, my celadons look pretty lack luster. In the last
firing they had a nice green on thicker parts, speckled on stoneware, and a
cool ice green on porcelain. This firing was hotter. It's not washed out du=
e
to ash- even some of the protected pieces are more gray and less green.
It's a custer/silica/whiting/ball clay/ 2% iron glaze. I don't have the
recipe in front of me, but suffice to say- it was good in the last fire, no=
t
in this one. The latest firing was hotter- cone 12 well down all around. I
had more coal bed at the end of the firing, so I may not have had an
oxidation period right at the end of the firing, which I normally have-
might that be the issue? Celadon normally wants reduction, correct?
ivor and olive lewis on sun 19 sep 10
Dear Paul Haigh, Dick White and Bill Schran,
I take it you all have studied the work of Robert Tichane, "Celadon Blues.
Re-create Ancient Chinese Celadon Glazes" 1998. ISBN 0-914267-03-5.
One feature of this latter printing is coloured photographs that illustrate
in an empirical way variations in colour due to altered composition and
varied firing schedules.
This might be a good time to remind newer members of the value of Nigel
Wood's book, "Chinese Glazes", 1999, ISBN 90-5703-23-25
I would be surprised if Calcium Oxide was melting at Cone 6. A more probabl=
e
explanation for a fraction to remain in the unchanged state is that there
may be insufficient molten or vitrified material at cone 6 into which this
refractory oxide can dissolve. Substituting Wollastonite might restore both
translucency and a brighter surface.
Best regards,
Ivor Lewis,
REDHILL,
South Australia
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