brandon2@SUPPORTYOURLOCALPOTTER.COM on sun 22 apr 12
We built a small crossdraft cat salt kiln a couple years ago...we used a
few rows of soft brick in the arch and immersed the bricks in various
washes to test their resistance. Immersing the brick vs brushing made a
significant difference in the life. We did a few with the class shino and
they held out a little longer but now at close to 30 firings they're all
shot to hell. The door was soft brick and we immersed all those as well,
held up for 20+ firings before we had to replace a few. We also made up a
homemade castable for the top part of the arch that has held up
surprisingly well. Fireclay/Portland Cement/Alumina/Grog.
Brandon Phillips
> This makes perfect sense when you think about the chemistry of it. I'll
> test a few high alumina soft bricks in my kiln just for fun.
>
> -Ben
>
>
>
> ________________________________
> From: mel jacobson
> To: Clayart@LSV.CERAMICS.ORG
> Sent: Sunday, April 22, 2012 8:51 AM
> Subject: shino lining a salt kiln
>
> we have found that spraying a coat of
> shino glaze inside our salt kiln helps
> preserve it.
>
> sort of like hank says:=C2 get a coat of tight glaze
> on the surface and the salt has a hard time eating it up.
> mel
> not fool proof science in any stretch, but great
> food for thought.
> we call it `very soft science`.
> from: minnetonka, mn
> website: http://www.visi.com/~melpots/
> clayart link:=C2 http://www.visi.com/~melpots/clayart.html
>
mel jacobson on sun 22 apr 12
we have found that spraying a coat of
shino glaze inside our salt kiln helps
preserve it.
sort of like hank says: get a coat of tight glaze
on the surface and the salt has a hard time eating it up.
mel
not fool proof science in any stretch, but great
food for thought.
we call it `very soft science`.
from: minnetonka, mn
website: http://www.visi.com/~melpots/
clayart link: http://www.visi.com/~melpots/clayart.html
Hank Murrow on sun 22 apr 12
On Apr 22, 2012, at 8:51 AM, mel jacobson wrote:
> we have found that spraying a coat of
> shino glaze inside our salt kiln helps
> preserve it.
>=3D20
> sort of like hank says: get a coat of tight glaze
> on the surface and the salt has a hard time eating it up.
> mel
Hank replies;
We built a salt kiln at the U of Oregon of 85% Silica bricks from =3D
A.P.Green in Troy, ID, thinking that the bricks would be glazed with =3D
sodium and prevent a more intrusive attack. Worked like a charm, the =3D
kiln finally failed when the molten salt filled the joints in the floor, =
=3D
solidified, expanded, and then re-melted, solidified and expanded. Over =3D
dozens of fires the joints opened to around 1.5" width!
The walls and arch were Ok, but the floor was destroyed. That led to my =3D
theory of using castable to minimize both wall thickness and number of =3D
joints. A side benefit is that castable panels can be replaced without =3D
tearing down the kiln.
Mel is a keen observer of what he sees. People who pay for the materials =
=3D
they use often are more observant.
Cheers, Hank=3D
James Freeman on sun 22 apr 12
On Sun, Apr 22, 2012 at 1:10 PM, Hank Murrow wrote:
...the kiln finally failed when the molten salt filled the joints in the
floor, solidified, expanded, and then re-melted, solidified and expanded.
Over dozens of fires the joints opened to around 1.5" width!
We built a salt kiln at the local college about 6 or 7 years ago. The
students stacked the brick, and I welded the frame (using the school's
Korean War surplus Air Force mobile welder which was the size of a
minivan!). Over the course of 3 or 4 years, the kiln failed in precisely
the manner Hank described. The hard brick (high alumina) was still in good
shape, but the floor seams had pushed out to about 1/2", and all of the
walls were severely bowed out, at least 4" in the centers. The kiln looked
like one of Clayton Bailey's jugs of "Claytonium", or like it had contained
an explosion. The kiln tech had welded spacers off the frame, then heavy
iron crosspieces, to try to hold the walls in. They finally tore it down
and rebuilt it within the existing frame two years ago. I'm not sure how
it is holding up, but I expect the same thing will happen again.
...James
James Freeman
"Talk sense to a fool, and he calls you foolish."
-Euripides
http://www.jamesfreemanstudio.com
http://www.flickr.com/photos/jamesfreemanstudio/
http://www.jamesfreemanstudio.com/resources
Ben Morrison on sun 22 apr 12
This makes perfect sense when you think about the chemistry of it. I'll tes=
=3D
t a few high alumina soft bricks in my kiln just for fun.=3D0A=3D0A-Ben=3D0=
A=3D0A=3D
=3D0A=3D0A________________________________=3D0A From: mel jacobson 2@VISI=3D
.COM>=3D0ATo: Clayart@LSV.CERAMICS.ORG =3D0ASent: Sunday, April 22, 2012 8:=
51 A=3D
M=3D0ASubject: shino lining a salt kiln=3D0A =3D0Awe have found that sprayi=
ng a c=3D
oat of=3D0Ashino glaze inside our salt kiln helps=3D0Apreserve it.=3D0A=3D0=
Asort of=3D
like hank says:=3DA0 get a coat of tight glaze=3D0Aon the surface and the =
salt=3D
has a hard time eating it up.=3D0Amel=3D0Anot fool proof science in any st=
retc=3D
h, but great=3D0Afood for thought.=3D0Awe call it `very soft science`.=3D0A=
from: =3D
minnetonka, mn=3D0Awebsite: http://www.visi.com/~melpots/=3D0Aclayart link:=
=3DA0 =3D
http://www.visi.com/~melpots/clayart.html
Vince Pitelka on sun 22 apr 12
James Freeman wrote:
"We built a salt kiln at the local college about 6 or 7 years ago. Over th=
e
course of 3 or 4 years, the kiln failed in precisely the manner Hank
described. The hard brick (high alumina) was still in good shape, but the
floor seams had pushed out to about 1/2", and all of the walls were severel=
y
bowed out, at least 4" in the centers. The kiln tech had welded spacers of=
f
the frame, then heavy iron crosspieces, to try to hold the walls in. They
finally tore it down and rebuilt it within the existing frame two years ago=
.
I'm not sure how it is holding up, but I expect the same thing will happen
again."
Hi James -
I know that this can happen as a result of what Hank described, but it's a
very slow process. The effect is drastically accelerated in a salt kiln
built from high-alumina bricks. They are not appropriate for salt and soda
kilns. I know it is counterintuitive, but you want to use plain high-duty
clay bricks for salt and soda kilns unless one is so lucky as to get a load
of zircon bricks from NASA or some other source. Alumina resists salt in
wadding and shelf-wash, but high-alumina bricks remain open and porous, and
the salt fumes penetrate the body of the brick, causing expansion and
spalling. In 1997 we got a huge donation of brick from AP Green when they
sold out to Harbison Walker. The bricks we got all came from the AP Green
plant in Bessemer, Alabama, just outside Birmingham. Most of what they had
were Kruzite 70% alumina bricks for the steel industry that was quickly
declining in Birmingham. We hauled quite a few truckloads from Bessemer to
Smithville, TN, and built our big "Hoggama" wood kiln and a 60 cubic foot
salt kiln. The Hoggama is still going strong, but the Kruzite salt kiln
lasted only two years. What a bummer that was, after we built such a
beautiful kiln. Steve Robison and Kathleen Guss were my
artists-in-residence at the time, and they put a huge amount of work into
that kiln and it was such a beauty. It was heartbreaking to see how it
moved around over just two years as those Kruzites expanded and shifted.
Very sad to tear it down after just two years, but I learned a valuable
lesson. The next salt kiln was built out of high-duty hardbrick and lasted
ten years.
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpitelka@dtccom.net
http://iweb.tntech.edu/wpitelka/
ivor and olive lewis on mon 23 apr 12
Dear mel jacobson,
Perhaps you are not quite far from the money.
Correct me if I am off line but I understood Shino Glazes were loaded with
Soda. Perhaps the rate of degradation is retarded because your shino surfac=
e
is already saturated with Sodium Ions. Their presence may prevent further
chemical reactions.
Sincerely,
Ivor Lewis,
REDHILL,
South Australia
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