Michael Wendt on sat 30 oct 10
Judy,
My medium blue is a chun recipe with the tin left out and 3%
titanium dioxide plus 1/2 % cobalt oxide added.
That is where the opal look seems to come from is a glaze
like a chun that also contains TiO2.
see:
http://www.wendtpottery.com/serve.htm
although you would need a closer view to really see the
complex character of the glaze.
Regards,
Michael Wendt
Judy wrote:
I keep seeing pictures of pottery with this blue glaze that
I love, but I
can not find a recipe for it. It seems to be a popular
glaze because I have
seen it used by lots of potters. I have tried a lot of
blues, but I can't
find anything like it. It is a medium blue with speckles in
it. Almost
like the blue part of floating blue without the brown. Does
anyone know
what this blue could be. It kind of reminds me of an opal.
I use B-mix
white stoneware clay or porcelain and I fire my glazes in
oxidation to cone
6. I uploaded a picture of a saucer that has this glaze on
it to my web
site. The saucer was made by Mary Cuzack. Here is the URL
http://ww2.nscc.edu/smith_judy/blue.htm
thanks,
Judy Smith
Judy Smith on sat 30 oct 10
I keep seeing pictures of pottery with this blue glaze that I love, but I
can not find a recipe for it. It seems to be a popular glaze because I hav=
e
seen it used by lots of potters. I have tried a lot of blues, but I can't
find anything like it. It is a medium blue with speckles in it. Almost
like the blue part of floating blue without the brown. Does anyone know
what this blue could be. It kind of reminds me of an opal. I use B-mix
white stoneware clay or porcelain and I fire my glazes in oxidation to cone
6. I uploaded a picture of a saucer that has this glaze on it to my web
site. The saucer was made by Mary Cuzack. Here is the URL
http://ww2.nscc.edu/smith_judy/blue.htm
thanks,
Judy Smith
Liisa Reid on thu 4 nov 10
Judy asked about a medium blue speckled glaze. =3DA0 =3DA0I don't know
if this is the one, but the photo she posted does look quite similar
to a glaze I posted several years ago. =3DA0That posting was in response
to one from Craig Martell about a speculation of Ian Currie's that
zinc might be helpful in producing a chun blue glaze.
I've reposted an edited version of my response below, with some
extra details:
This is interesting because the glaze I have used for many years
reliably turns iron blue. There are no colorants in the
glaze. =3DA0The blues are from the iron in the slip, which is under the
glaze, an effect caused by the boron in the gerstley borate, and
perhaps the zinc oxide.
=3DA0At times this has been to my frustration when I wanted it to stay brow=
n.
The intensity can vary from a pale blue to a deep midnight blue, almost
black. =3DA0If very thin it stays brown. =3DA0The shade of blue depends on =
the
thickness of the glaze, and on the concentration of iron. =3DA0I have alway=
s
thought of it as an iron/ boron blue, but that hasn't seemed a sufficient
explanation. =3DA0I have wondered about the zinc, but what I read just said
it makes muddy brown.
Here's a link to a photo of a bowl using this glaze slip combo:
http://flic.kr/p/8QNDnZ
The recipe with the ingredients I was using from about 2000 to 2006 is
posted below. =3DA0(I have since moved from Vermont to
Tucson and am no longer pursuing this body of work.)
=3DA0E Clear Glaze - cone 5 to 6 oxidation:
=3DA0Gerstley Borate 19.3
=3DA0Feldspar-g200 42.3
=3DA0Talc-Nytal 7.1
=3DA0Zinc Oxide 4.5
=3DA0Silica 24.8
=3DA0English China Clay 2.0
Iron Slip:
75 % red iron oxide
25% porcelain scrap
Eyeballed and mixed thick.
Add enough sodium silicate or darvan to make it very fluid.
Brush onto clay while clay is still damp (freshly thrown, but
ribbed free of throwing slurry).
Sgrafitto decoration is done when the pot is just past leather hard.
I generally brushed the glaze on for best control of thickness.
Veegum Cer was added to make the glaze brushable.
Note: =3DA0the black glaze is Ron and John's Licorice, with a
thin coat of the clear over the licorice.
Hope this helps.
Liisa, formerly in Vermont, now in Tucson where the weather is
incredibly pleasant and the desert hiking fabulous
On Sat, Oct 30, 2010 at 3:05 PM, Judy Smith wrote:
>
> I keep seeing pictures of pottery with this blue glaze that I love, but I
> can not find a recipe for it. =3DA0It seems to be a popular glaze because=
I=3D
have
> seen it used by lots of potters. =3DA0I have tried a lot of blues, but I =
ca=3D
n't
> find anything like it. =3DA0It is a medium blue with speckles in it. =3DA=
0Alm=3D
ost
> like the blue part of floating blue without the brown. =3DA0Does anyone k=
no=3D
w
> what this blue could be. =3DA0It kind of reminds me of an opal. =3DA0I us=
e B-=3D
mix
> white stoneware clay or porcelain and I fire my glazes in oxidation to co=
=3D
ne
> 6. =3DA0I uploaded a picture of a saucer that has this glaze on it to my =
we=3D
b
> site. =3DA0The saucer was made by Mary Cuzack. =3DA0Here is the URL
> http://ww2.nscc.edu/smith_judy/blue.htm
>
> thanks,
> Judy Smith
--
Liisa Reid
liisa.1.reid@gmail.com
520-300-1411
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