Susan Wallace on tue 1 aug 00
This is for Penny:
I've been working with Mason stains in slips for years using a clear glaze
over them (at both Cone 6 and Cone 10). This peeling of the glaze is a real
problem.
1. If the underglaze/stain/engobe is applied too thickly, this peeling
will occur. This especially happens if you carve a pot, then use an
underglaze in the carving, then use a clear glaze over it. (I don't do this
anymore, for sure.)
2. If the clear glaze is too thick, this will also happen.
I have found that I need to make sure that the clear glaze is as thin as it
can be and still not be too thin. Then I quickly dip the pot in the glaze --
in and out. When the glaze is thoroughly dry (sometimes it's necessary to
wait until the next day for this step), I sand off the thicker areas of
glaze with a fine sandpaper, or I use a thin metal rib. I try to make all
areas of the glaze approximately the same thickness overall. This step takes
a long time, is not efficient, and has the potential for driving you crazy,
but it seems to work -- most of the time. However, I sometimes get some
crawling of the glaze anyway and have to touch it up and refire. Also, I
wear a mask while doing the sanding/scraping, since it creates a lot of
dust.
I have been told that the glaze crawls off the slipped areas, since the
slip is really dry and has a dusty texture (even if you sponge it
beforehand). Maybe there are other reasons for this problem.
Good luck!
Susan Wallace in Grand Junction, CO where it's hot, hot, hot and hazy!
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Penny Hosler on tue 1 aug 00
Thank you ! I don't feel nearly so stupid now. I think my UG was
too thick, for one thing. I may try using less, and also may add
some frit to it to encourage fusion with the clay. It's pretty
depressing when you've made a sink with lots of relief decoration and
dried it carefully for 1-1/2 months, bisqued successfully, and then
the glaze sends you down the tubes. aaaaarrrrrggghhh
Penny
----- Original Message -----
From: "Susan Wallace"
To:
Sent: Tuesday, August 01, 2000 6:52 AM
Subject: Glaze lifting underglaze
> This is for Penny:
> I've been working with Mason stains in slips for years using a
clear glaze
> over them (at both Cone 6 and Cone 10). This peeling of the glaze is
a real
> problem.
> 1. If the underglaze/stain/engobe is applied too thickly, this
peeling
> will occur. This especially happens if you carve a pot, then use an
> underglaze in the carving, then use a clear glaze over it. (I don't
do this
> anymore, for sure.)
> 2. If the clear glaze is too thick, this will also happen.
> I have found that I need to make sure that the clear glaze is as
thin as it
> can be and still not be too thin. Then I quickly dip the pot in the
glaze --
> in and out. When the glaze is thoroughly dry (sometimes it's
necessary to
> wait until the next day for this step), I sand off the thicker areas
of
> glaze with a fine sandpaper, or I use a thin metal rib. I try to
make all
> areas of the glaze approximately the same thickness overall. This
step takes
> a long time, is not efficient, and has the potential for driving you
crazy,
> but it seems to work -- most of the time. However, I sometimes get
some
> crawling of the glaze anyway and have to touch it up and refire.
Also, I
> wear a mask while doing the sanding/scraping, since it creates a lot
of
> dust.
> I have been told that the glaze crawls off the slipped areas,
since the
> slip is really dry and has a dusty texture (even if you sponge it
> beforehand). Maybe there are other reasons for this problem.
> Good luck!
> Susan Wallace in Grand Junction, CO where it's hot, hot, hot and
hazy!
>
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__
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http://www.hotmail.com
>
>
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Autumn Downey on wed 2 aug 00
Penny, what you are planning to do sounds like it may do the trick. The mix
I use has quite alot of glaze in it, and seems to give few problems, so the
frit may be the answer.
If not, I wonder if firing a cone higher (to 05, if you are now doing 06)
during bisque might not also help with fusing the underglaze.
Wet sponging surfaces prior to glazing is also necessary to remove dust
that's settled on pots or is formed from the slip/UG itself.
Autumn Downey
At 03:12 PM 2000-08-01 -0700, you wrote:
>Thank you ! I don't feel nearly so stupid now. I think my UG was
>too thick, for one thing. I may try using less, and also may add
>some frit to it to encourage fusion with the clay. It's pretty
>depressing when you've made a sink with lots of relief decoration and
>dried it carefully for 1-1/2 months, bisqued successfully, and then
>the glaze sends you down the tubes. aaaaarrrrrggghhh
>Penny
>
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