Chuck Nunnelly on mon 20 dec 99
During a glaze session last night, I was using two glazes (both Tony Hansen's
5-20's base). Glaze the piece all over with one glaze and dipping the top
in the other glaze. On one pot the second application cracked and pulled
away a little. I can smooth it out with my finger, but am unsure if this
will cause glaze problems during the firing. Also was the cracking a result
of double dipping too quickly or not?
Questions on a dreary, wet day in Va.
Chuck Nunnelly
Mechanicsville VA
Cindy Strnad on tue 21 dec 99
Chuck,
IMO, you have the glaze too thick. I use Tony's 5x20 glaze, too, and it's my
experience that if you fire this pot as is, the glaze will crawl. I haven't
gotten around to it, but intend to try this glaze with at least half of the
kaolin calcined. Calcining the kaolin should make for less wet to dry
shrinkage and less chance of crawling.
Cindy Strnad
Earthen Vessels Pottery
Custer, SD
Chris Schafale on tue 21 dec 99
Hi Chuck,
In my experience with this glaze, this is a very common event. The
cracks generally lead to crawling (if you're lucky -- if you're not,
they lead to flakes of glaze falling off and melting on your
shelves). Rubbing the cracks with your finger will only help if
they are quite small and the edges haven't lifted at all, and may
not even work then. My advice: don't bother firing pieces like this
-- wash off the glaze and try again. I would guess that your glaze
may be a bit too thick. Check the specific gravity, thin it some if
it is more than 1.45 or so, and see how that works. If the specific
gravity is already low (1.40 or less), you have my sympathies. This
is the problem that has been plaguing me for the last year.
Speaking from bitter experience,
Chris
> ----------------------------Original message----------------------------
> During a glaze session last night, I was using two glazes (both Tony Hansen's
> 5-20's base). Glaze the piece all over with one glaze and dipping the top
> in the other glaze. On one pot the second application cracked and pulled
> away a little. I can smooth it out with my finger, but am unsure if this
> will cause glaze problems during the firing. Also was the cracking a result
> of double dipping too quickly or not?
>
> Questions on a dreary, wet day in Va.
>
> Chuck Nunnelly
> Mechanicsville VA
>
>
Light One Candle Pottery
Fuquay-Varina, NC
candle@intrex.net
L Skeen on tue 21 dec 99
Chuck Nunnelly wrote:
> ----------------------------Original message----------------------------
> During a glaze session last night, I was using two glazes (both Tony Hansen's
> 5-20's base). Glaze the piece all over with one glaze and dipping the top
> in the other glaze. On one pot the second application cracked and pulled
> away a little. I can smooth it out with my finger, but am unsure if this
> will cause glaze problems during the firing. Also was the cracking a result
> of double dipping too quickly or not?
>
> Questions on a dreary, wet day in Va.
>
> Chuck Nunnelly
> Mechanicsville VA
Chuck,
With that glaze, you're gonna have problems if you get it too thick. The top
coat of glaze will peel off like a banana. If you smooth it back down with your
finger or whatever and can make it stick, it'll stay on the pot, but after firin
you will be able to see where the crackles were. I like the glaze base, but
usually will brush on a very thin coat of something else over just so it'll move
a bit.
Good luck!
Lisa in NC
pam easley on wed 22 dec 99
Methinks the glaze was too thick. This happens to me, as I frequently do
just as you do, and I just smooth off the cracks and blips and fire it.
There is a visual texture to the rim, but not (usually) crawling to leave
bare clay body. My pottery partner hates the effect, but I like it, and so
do those who buy the pots, and order ones just like them. Try firing the one
with cracks, and see how it works. If it crawls horrifically, refire after
dobbing with glaze on the bare places. Adds more visual texture and saves
the pot. Good luck. Enjoy the test.
Pam in Seattle
Chris Schafale on wed 22 dec 99
Yes, I forgot to mention, it does help a great deal to calcine some
of the clay. 50% should be plenty. More than that and it begins to
lose its suspension properties and becomes too powdery when dry.
Chris
> ----------------------------Original message----------------------------
> Chuck,
>
> IMO, you have the glaze too thick. I use Tony's 5x20 glaze, too, and it's my
> experience that if you fire this pot as is, the glaze will crawl. I haven't
> gotten around to it, but intend to try this glaze with at least half of the
> kaolin calcined. Calcining the kaolin should make for less wet to dry
> shrinkage and less chance of crawling.
>
> Cindy Strnad
> Earthen Vessels Pottery
> Custer, SD
>
>
Light One Candle Pottery
Fuquay-Varina, NC
candle@intrex.net
Tom Wirt on wed 22 dec 99
> ----------------------------Original message----------------------------
> Chuck,
Another thought in this thread. Don't know how you're dipping, but with
some of these prone to crack glazes, you will have better results if you do
the second dip immediately following the first....as soon as the sheen
starts to leave the pot. This allows the second coat to wet the undercoat
better, and the first coat hasn't shrunk that much yet. So they get to
shrink together....sort of a glaze buddy system.
R. Tichane discovered as one of the ways to ancients got the old reds and
temmokus. He analyzed it by taking sideways slices and looking at them
under high power. The melding of the layers indicated (and could be
duplicated) by applying wet on wet.
I notice in reading Hare's Fur, Tortoiseshell and Partridge Feathers that
many of the old black/browns were achieved this way too. Single layer is
brown, double layer is black.
Tom Wirt
Joan & Tom Woodward on wed 22 dec 99
I'm confused. . . what kind of "something else" would you brush over a
dipped glaze?
Thanks for clarifying! Babe in the woods re. glazes, Joan (in Alaska where
we've had f reezing rain on top of a foot of snow for absolutely disastrous
walking and driving conditions. ) Happy Solstice!
----- Original Message -----
From: L Skeen
To:
Sent: Tuesday, December 21, 1999 10:42 AM
Subject: Re: Double Dip Cracks
> ----------------------------Original message----------------------------
> Chuck Nunnelly wrote:
>
> > ----------------------------Original message----------------------------
> > During a glaze session last night, I was using two glazes (both Tony
Hansen's
> > 5-20's base). Glaze the piece all over with one glaze and dipping the
top
> > in the other glaze. On one pot the second application cracked and
pulled
> > away a little. I can smooth it out with my finger, but am unsure if
this
> > will cause glaze problems during the firing. Also was the cracking a
result
> > of double dipping too quickly or not?
> >
> > Questions on a dreary, wet day in Va.
> >
> > Chuck Nunnelly
> > Mechanicsville VA
>
> Chuck,
> With that glaze, you're gonna have problems if you get it too thick. The
top
> coat of glaze will peel off like a banana. If you smooth it back down
with your
> finger or whatever and can make it stick, it'll stay on the pot, but after
firin
> you will be able to see where the crackles were. I like the glaze base,
but
> usually will brush on a very thin coat of something else over just so
it'll move
> a bit.
> Good luck!
> Lisa in NC
Robert Santerre on wed 22 dec 99
Chuck, I've had similar problems with a tenmoku glaze, dipping another glaze on
top of it caused the tenmku to lift up and crack. The thicker the tenmoku
application the greater the cracking and the drier the tenmoku the more
cracking. I have dealt with the problem in three ways: a.) added some gum
arabic (about 400 ml per 5 gal of glaze), b.) carefully watch the thickness of
the tenmoku and c.) catch the dryness of the tenmoku just right (can't really
explain this, but the glazed pot ready for the second dipping will be dry enough
to handle, but still feel a little cool as opposed to a fully dried surface wher
the glaze feels like it is at room temp.). This being said, I've fired pots wit
pretty seriously crackled glaze and the crackling usually seals over just fine.
Occasionally the glaze appears to have pulled completely away from the pot
leaving small areas essentially unglazed after firing, but I never worry about a
small amount of cracking - this will always seal over.
Hope this helps, Bob
rfsanterre@iquest.net
//////////////////////////////////////////////////////////////////////////////
Chuck Nunnelly wrote:
> ----------------------------Original message----------------------------
> During a glaze session last night, I was using two glazes (both Tony Hansen's
> 5-20's base). Glaze the piece all over with one glaze and dipping the top
> in the other glaze. On one pot the second application cracked and pulled
> away a little. I can smooth it out with my finger, but am unsure if this
> will cause glaze problems during the firing. Also was the cracking a result
> of double dipping too quickly or not?
>
> Questions on a dreary, wet day in Va.
>
> Chuck Nunnelly
> Mechanicsville VA
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