Tony Ferguson on wed 2 may 01
Ken,
Pinholes and shino are pretty synonymous at least with
my experience--and I like the effect. The more grog
in your body the more and or larger your pinholes will
be. If you just mixed your shino up and its airated,
you will have more bubbles. If there is any soap in
your glaze bucket, you will have more bubbles. With a
shino with 4% soda ash, the insides of my pots are
unbroken, no holes, the outside tends to have more
pinholes, especially if I have cut away the clay to
expose more of the grog.
I would venture to say that amount of grog affects
pinholing and the amount of soda ash in your glaze
will affect pinholing. Try it, you might like it with
pinholes. Shino stays where shino is put with my
experience. So if you see a crater, there will be a
crater.
Jan Severson, a fine Minnesota potter, has a really
silky shino for functional ware.
Hope this helps.
Tony, Duluth MN
--- "Kenneth J. Nowicki" wrote:
> Hi Clayarters...
>
> I'm a recent "newbie" to the "Shino glaze craze" and
> am already feeling
> another clay addiction forming within myself.
> Recently, a friend and I did a
> few random glaze tests from Mel & Tom's Shino
> article published in CM last
> year. We tested 7 glazes and ended up with 3 we
> wanted to make batches of
> (i.e. - Malcolm Davis Shino w/6% Redart; GWU Shino
> [RIT Carbon-Trap] w/9.5%
> Rutile; and Jack Troy's Carbon-Trap).
>
> We both had discovered that by dipping our pieces
> into Jack Troy's
> Carbon-Trap glaze, the surface on the piece
> developed little tiny pinholes
> all over it as it was drying on the bisqueware. I
> have never seen this before
> and am curious to what might be causing it. When we
> tried brushing the glaze
> on the pots, it still continued to happen, though
> not nearly as bad. Finally,
> we resorted to spraying the pots with an airgun
> which seemed to eliminate the
> problem entirely. Whether or not these little
> pinholes would flatten out in
> the glaze melt or not... I'm not sure... we are
> firing a Shino load as I type
> this, and won't see the results until Friday
> morning. Normally, I would think
> they would flatten out in a ^10 firing... but given
> the quirky
> characteristics of Shinos... (see side note below on
> glazes
> cracking/crawling) we didn't want to take a
> chance... so we ended up scraping
> glaze off a few pieces and reglazing them with an
> airgun. Does anyone else
> out there know what might be causing this and how to
> remedy the situation? We
> already tried thinning the glaze a bit which seemed
> to make no difference in
> the pinholing.
>
> Cracking Glazes:
>
> On a side note, before all of this pinholing
> occurred on Jack's glaze, we
> discovered that Malcolm's Shino recipe was giving us
> some problems with the
> glaze cracking excessively after glazing our
> bisqueware as it dried. This is
> the kind of cracking that looks like a dried up lake
> bed. Sometimes it would
> just be where the glaze was thicker and other times
> it seemed to be all over
> the piece. This mostly happened while dipping, but
> also happened somewhat
> while brushing as well. We finally figured out that
> perhaps our glaze batch
> was too thick, and thinned it out substantially.
> This seemed to alleviate the
> problem. Easy fix. But wondering if the addition of
> the 6% Redart was making
> this glaze so prone to this "cracking" like it did.
> When fired, it appeared
> not to melt back down and flatten out, but instead
> pulled away from the clay
> body and crawled... and sometimes left a very unique
> and interesting surface.
> Although this surface is fine for some work, it was
> not desirable for
> everything. Additionally, when using "calcined"
> E.P.K. and "calcined" Redart
> in the recipe, as Malcolm suggested to my friend...
> our results seemed to be
> even a MORE crawling effect... with an almost
> guaranteed even crawled surface
> all over the piece where the glaze was applied. It
> actually looks very cool
> on some works, but obviously isn't too conducive to
> functional work where
> food or liquids come in contact.
>
> We are curious about other Clayarter's experiences
> along these lines using
> Shinos that may have behaved similarly. This is all
> so new to us and we are
> thirsty for information. Any comments or information
> provided would be
> greatly appreciated. TIA.
>
> Glaze Recipes Used
> Cone 10 - Reduction
> ..................................................
> Malcolm Davis Shino
>
> Soda Ash 17.27
> Kona F-4 Feldspar 9.82
> Nepheline Syenite 40.91
> Edgar Plastic Kaolin 18.18
> Kentucky Ball Clay (OM 4) 13.82
>
> 100%
> Cedar Heights Redart + 6.0
>
> ................................................
> GWU Shino (RIT Carbon-Trap) Glaze
>
> Soda Ash 4.0
> Nepheline Syenite 45.0
> Kona F-4 Feldspar 18.4
> Spodumene 15.2
> Ball Clay 16.4
> Bentonite 1.0
>
> 100%
> Rutile + 9.5
>
> ..................................................
> Jack Troy's Carbon-Trap Glaze
>
> Soda Ash 7.77
> Kona F-4 Feldspar 33.98
> Nepheline Syenite 14.56
> Spodumene 29.13
> Ball Clay 4.85
> Kaolin 9.71
>
> 100%
> ..................................................
>
> Thanks in advance once again. :-)
>
> Ken
> in Encino, California
>
>
_________________________________________________________________________=
_____
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change
> your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be
> reached at melpots@pclink.com.
>
=3D=3D=3D=3D=3D
--Tony Ferguson, fergyart@yahoo.com315 N. Lake Ave. Apt 401Duluth, MN 55=
806(218) 727-6339Looking to see, buy or barter artwork go to:http://acad.=
uwsuper.edu/www/aferguso/fergyart.htm
Kenneth J. Nowicki on wed 2 may 01
Hi Clayarters...
I'm a recent "newbie" to the "Shino glaze craze" and am already feeling
another clay addiction forming within myself. Recently, a friend and I did a
few random glaze tests from Mel & Tom's Shino article published in CM last
year. We tested 7 glazes and ended up with 3 we wanted to make batches of
(i.e. - Malcolm Davis Shino w/6% Redart; GWU Shino [RIT Carbon-Trap] w/9.5%
Rutile; and Jack Troy's Carbon-Trap).
We both had discovered that by dipping our pieces into Jack Troy's
Carbon-Trap glaze, the surface on the piece developed little tiny pinholes
all over it as it was drying on the bisqueware. I have never seen this before
and am curious to what might be causing it. When we tried brushing the glaze
on the pots, it still continued to happen, though not nearly as bad. Finally,
we resorted to spraying the pots with an airgun which seemed to eliminate the
problem entirely. Whether or not these little pinholes would flatten out in
the glaze melt or not... I'm not sure... we are firing a Shino load as I type
this, and won't see the results until Friday morning. Normally, I would think
they would flatten out in a ^10 firing... but given the quirky
characteristics of Shinos... (see side note below on glazes
cracking/crawling) we didn't want to take a chance... so we ended up scraping
glaze off a few pieces and reglazing them with an airgun. Does anyone else
out there know what might be causing this and how to remedy the situation? We
already tried thinning the glaze a bit which seemed to make no difference in
the pinholing.
Cracking Glazes:
On a side note, before all of this pinholing occurred on Jack's glaze, we
discovered that Malcolm's Shino recipe was giving us some problems with the
glaze cracking excessively after glazing our bisqueware as it dried. This is
the kind of cracking that looks like a dried up lake bed. Sometimes it would
just be where the glaze was thicker and other times it seemed to be all over
the piece. This mostly happened while dipping, but also happened somewhat
while brushing as well. We finally figured out that perhaps our glaze batch
was too thick, and thinned it out substantially. This seemed to alleviate the
problem. Easy fix. But wondering if the addition of the 6% Redart was making
this glaze so prone to this "cracking" like it did. When fired, it appeared
not to melt back down and flatten out, but instead pulled away from the clay
body and crawled... and sometimes left a very unique and interesting surface.
Although this surface is fine for some work, it was not desirable for
everything. Additionally, when using "calcined" E.P.K. and "calcined" Redart
in the recipe, as Malcolm suggested to my friend... our results seemed to be
even a MORE crawling effect... with an almost guaranteed even crawled surface
all over the piece where the glaze was applied. It actually looks very cool
on some works, but obviously isn't too conducive to functional work where
food or liquids come in contact.
We are curious about other Clayarter's experiences along these lines using
Shinos that may have behaved similarly. This is all so new to us and we are
thirsty for information. Any comments or information provided would be
greatly appreciated. TIA.
Glaze Recipes Used
Cone 10 - Reduction
..................................................
Malcolm Davis Shino
Soda Ash 17.27
Kona F-4 Feldspar 9.82
Nepheline Syenite 40.91
Edgar Plastic Kaolin 18.18
Kentucky Ball Clay (OM 4) 13.82
100%
Cedar Heights Redart + 6.0
................................................
GWU Shino (RIT Carbon-Trap) Glaze
Soda Ash 4.0
Nepheline Syenite 45.0
Kona F-4 Feldspar 18.4
Spodumene 15.2
Ball Clay 16.4
Bentonite 1.0
100%
Rutile + 9.5
..................................................
Jack Troy's Carbon-Trap Glaze
Soda Ash 7.77
Kona F-4 Feldspar 33.98
Nepheline Syenite 14.56
Spodumene 29.13
Ball Clay 4.85
Kaolin 9.71
100%
..................................................
Thanks in advance once again. :-)
Ken
in Encino, California
Kenneth J. Nowicki on mon 7 may 01
Hi Dave,
Thanks for your response. Surprisingly, you are the only one who responded
from the entire Clayart list.
In a message dated 05/03/01, Dave wrote:
> In my limited experience, any glaze with more than 10% ball clay will
> tend to mud crack (shrinkage cracks) on bisque or bone dry clay. High clay
> recipes are great for singlefire application to leather hard, but otherwise
> problematic.
This explains the problems with the Malcolm Davis Shino recipe... (13.82%
Ball Clay) but leaves me scratching my head about the other two we tested.
The pinholing we experienced on the Jack Troy glaze (4.8% Ball Clay) ended up
flattening out in the kiln pretty much. Didn't have any cracking problems
with the GWU (RIT Carbon-Trap) glaze at all... which had 16.4% Ball Clay in
it. Go figure. ...lol
> If you don't want to reduce the ball clay, or the amount of clay in the
> recipe, you can try adding CMC gum, which seems to help some.
Will try this... thanks for the tip. :-) Any suggestions how much CMC?
Ken
in Encino, CA
> Thinning is a good solution, only if you want a thick coat of glaze
then
> you need a second application. Hmmmm.
> I've decided crawling is an unacceptable fault for my work and I modify
> recipes to eliminate the offending quantities of clay if I get the mud
> cracking that will pretty much guarantee crawling. I've pretty much
> eliminated bentonite as a suspender unless I have a very low clay recipe
> because of this problem. It sounds like you have all this figured out, so
> I'm probably not being helpful.
> The glaze is just shrinking too much and won't fit the pot.
> Good glazing!
> Dave Finkelnburg in Idaho
| |
|
