Scott Paulding on mon 16 aug 04
Hello,
I have a recipe for a great very, very subtle blue (almost white) glaze that
has great depth (especially on porcelain) and a somewhat 'waxy' finish. I use
it as a liner glaze. We call it Chun White (I know, there are probably 100s of
'chun' whites out there). Well this one in particular dries very powdery on the
pot. It rubs off way too easily, and when I put a glaze on top of it, the other
glaze actually rips the chin of the pot, or it cracks severely.
Because of this, I've had to learn to glaze the outside first, then the inside.
What a pain! If glaze drips when I pour it out, I get a streak of chun on the
outside of the pot. sometimes good, sometimes bad. Serendipity aside, sometimes
it just looks sloppy (other times, I encourage it :).
Well, I'm just curious if anyone know what in the glaze is making this happen.
Here's the ingredient list -- does anything jump out as drying in a very
powdery state:
kona f4 31
wollastonite 30
silica 15
grolleg 10
zircopax 7
dolomite 5
tin o2 2
It's the only glaze I use that has wollastonite in it, but I know a couple
other potters who use it w/out problems. Laguna offers three flavors: Nyad-200,
Vansil W-10 and Vansil W-10. Is there a big difference in these?
If not Wollastonite, what? Thanks in advance for the help,
-scott
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Earl Brunner on mon 16 aug 04
It doesn't have much clay in it; clay will give the glaze dry strength.
Grolleg is the only stuff there very claylike and you only have 10% of that.
The rest of the stuff is just powdered rock basically, so it acts powdery.
Earl Brunner
Las Vegas, NV
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Scott Paulding
Sent: Monday, August 16, 2004 12:48 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: powdery glazes
Hello,
I have a recipe for a great very, very subtle blue (almost white) glaze that
has great depth (especially on porcelain) and a somewhat 'waxy' finish. I
use
it as a liner glaze. We call it Chun White (I know, there are probably 100s
of
'chun' whites out there). Well this one in particular dries very powdery on
the
pot. It rubs off way too easily, and when I put a glaze on top of it, the
other
glaze actually rips the chin of the pot, or it cracks severely.
Because of this, I've had to learn to glaze the outside first, then the
inside.
What a pain! If glaze drips when I pour it out, I get a streak of chun on
the
outside of the pot. sometimes good, sometimes bad. Serendipity aside,
sometimes
it just looks sloppy (other times, I encourage it :).
Well, I'm just curious if anyone know what in the glaze is making this
happen.
Here's the ingredient list -- does anything jump out as drying in a very
powdery state:
kona f4 31
wollastonite 30
silica 15
grolleg 10
zircopax 7
dolomite 5
tin o2 2
Richard Aerni on mon 16 aug 04
Scott,
I don't know what is causing your glaze to go powdery as it dries on the
surface of the pot, but I do know that adding 2% bentonite to your glaze
batch will keep it from happening.
Best,
Richard Aerni
Rochester, NY
Gary Elfring on tue 17 aug 04
Hello Scott,
SP> I have a recipe for a great very, very subtle blue (almost white) glaze that
SP> has great depth (especially on porcelain) and a somewhat 'waxy' finish. I use
SP> it as a liner glaze. We call it Chun White (I know, there are probably 100s of
SP> 'chun' whites out there). Well this one in particular dries very powdery on the
SP> pot. It rubs off way too easily, and when I put a glaze on top of it, the other
SP> glaze actually rips the chin of the pot, or it cracks severely.
There's not much clay in the glaze. It's very easy to fix, without
changing the glaze formula at all. Just mix up some CMC and use that
solution in place of water in the glaze. This will make the dry glaze
stick to the pot and itself. The dry glaze on the pot will also look
different, but will fire exactly the same. And it won't be fragile or
rub off.
Think of your current glaze this way: go to the beach and put some
fine beach sand in a bucket with water. Stir the water and sand up and
dip a bisque pot in it. The sand will stick to the pot, while the sand
is wet. Once the sand dries, it falls off because the only thing
holding it to the pot was the water. If you substitute a CMC solution
for water, the CMC will hold even sand to the pot (utill it burns off
in the kiln).
--
Best regards,
Gary
Ron Roy on fri 20 aug 04
I know this works - and you can also replace the Kaolin with Ball clay on a
mol for mol basis and removing some silica to keep the ratio the same -
send me the recipe and I will do it if you can't.
RR
>Scott,
>I don't know what is causing your glaze to go powdery as it dries on the
>surface of the pot, but I do know that adding 2% bentonite to your glaze
>batch will keep it from happening.
>Best,
>Richard Aerni
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
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