Vince Pitelka on mon 26 oct 09
We have been using the Larkin nitride bonded SC shelves in our soda kiln fo=
r
about a year, without wash, and are having more and more trouble with
foaming on the surface of the shelves, especially where they get a little
more soda. It foams up enough to leave big gobs of gray scum on the bottom=
s
of some pots. Everything is always fired up on wads. It is damaging or
ruining quite a few pots, and I'd like to find a solution. Has anyone else
run into this? The foam scrapes off the shelves easily, leaving them clean
for the next firing, but it just isn't worth it using these shelves unless
we can prevent the foaming.
For those who do a lot of soda firing, what are your favorite shelves?
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpitelka@dtccom.net; wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka
ivor & olive lewis on tue 27 oct 09
Dear Vince Pitelka,
Under Oxidising conditions Silicon Carbide Shelves develop a skin of Silico=
n
Dioxide. This skin forms a protective coating which is resistant to the
penetration of more Oxygen which attacks Silicon Carbide.
Both Common Salt and Soda will react with Silica and create foam. As they
react with this protective Silica coating Chlorine is discharged from one
flux and Carbon dioxide from the other,
The incidence of these reactions can be limited by using a high Alumina Kil=
n
wash. I found 50/50 Kaolin/Aluminium Hydrate adequate for the task.
Best regards,
Ivor Lewis,
Redhill,
South Australia
June on tue 27 oct 09
Vince,
I solved that problem by spreading a very thin layers of alumina hydrate or=
oxide, on the shelves and use the palm of my hand to spread it evenly. the=
n use the flat end of my thumb along the edges to remove about 1/2"-3/4" of=
the material so I don't risk any falling on pots as I load. I do this on m=
y advancers as well and I no longer get any of that scumming.
My favorite shelves are advancers, without question. The nitride bonded can=
break over cone 11, maybe even sooner. I have about four of them and three=
broke - all in the same place, around the middle.
Regards,
June
http://www.shambhalapottery.blogspot.com
http://www.shambhalapottery.com
http://groups.yahoo.com/group/sodasaltfiring/
http://saltandsodafiring.ning.com/
http://ncclayclub.blogspot.com
________________________________
From: Vince Pitelka
To: Clayart@LSV.CERAMICS.ORG
Sent: Monday, October 26, 2009 10:00:39 PM
Subject: Use of Nitride Bonded Shelves in Soda
We have been using the Larkin nitride bonded SC shelves in our soda kiln fo=
r
about a year, without wash, and are having more and more trouble with
foaming on the surface of the shelves, especially where they get a little
more soda. It foams up enough to leave big gobs of gray scum on the bottom=
s
of some pots. Everything is always fired up on wads. It is damaging or
ruining quite a few pots, and I'd like to find a solution. Has anyone else
run into this? The foam scrapes off the shelves easily, leaving them clean
for the next firing, but it just isn't worth it using these shelves unless
we can prevent the foaming.
For those who do a lot of soda firing, what are your favorite shelves?
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpitelka@dtccom.net; wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka
William & Susan Schran User on tue 27 oct 09
On 10/26/09 10:00 PM, "Vince Pitelka" wrote:
> We have been using the Larkin nitride bonded SC shelves in our soda kiln =
for
> about a year, without wash, and are having more and more trouble with
> foaming on the surface of the shelves, especially where they get a little
> more soda. It foams up enough to leave big gobs of gray scum on the bott=
oms
> of some pots. Everything is always fired up on wads. It is damaging or
> ruining quite a few pots, and I'd like to find a solution. Has anyone el=
se
> run into this? The foam scrapes off the shelves easily, leaving them cle=
an
> for the next firing, but it just isn't worth it using these shelves unles=
s
> we can prevent the foaming.
Vince,
I don't do soda firing, so can't help from having experience, but was
wondering if coating the top of the shelf with alumina, that would dust off
or scrape off with the scum, might work to hold down the scum.
Certainly give a call to Donna or Marshall at Smith Sharpe for their
recommendations on shelves for soda firing .
Bill
--
William "Bill" Schran
wschran@cox.net
wschran@nvcc.edu
http://www.creativecreekartisans.com
William & Susan Schran User on tue 27 oct 09
On 10/27/09 7:20 AM, "June" wrote:
> I solved that problem by spreading a very thin layers of alumina hydrate =
or
> oxide, on the shelves and use the palm of my hand to spread it evenly. th=
en
> use the flat end of my thumb along the edges to remove about 1/2"-3/4" of=
the
> material so I don't risk any falling on pots as I load. I do this on my
> advancers as well and I no longer get any of that scumming.
>
> My favorite shelves are advancers, without question. The nitride bonded c=
an
> break over cone 11, maybe even sooner. I have about four of them and thre=
e
> broke - all in the same place, around the middle.
June,
I'm always reluctant to run my hand across a used kiln shelf - just never
know what might be on there even if it looks clean - have many little scars
before I wised up.
I use Advancer shelves in my electric kiln and sprinkle alumina on them fro=
m
a small cheap kitchen sieve. It allows me to control where and how much,
also keeping it away from the edges. I do this to help the catch plates for
my crystalline glazed pots, that are made with Soldate 60, to shrink/move
easily.
Bill
--
William "Bill" Schran
wschran@cox.net
wschran@nvcc.edu
http://www.creativecreekartisans.com
June on tue 27 oct 09
Bill, I use my heavy leather, old raku gloves to clean off the advancers an=
d never have a problem. I also have a shelf cleaning brick that I can use i=
f necessary. Those advancers are a dream!
Regards,
June
http://www.shambhalapottery.blogspot.com
http://www.shambhalapottery.com
http://groups.yahoo.com/group/sodasaltfiring/
http://saltandsodafiring.ning.com/
http://ncclayclub.blogspot.com
________________________________
From: William & Susan Schran User
To: June ; Clayart@LSV.CERAMICS.ORG
Sent: Tuesday, October 27, 2009 3:26:30 PM
Subject: Re: Use of Nitride Bonded Shelves in Soda
On 10/27/09 7:20 AM, "June" wrote:
> I solved that problem by spreading a very thin layers of alumina hydrate =
or
> oxide, on the shelves and use the palm of my hand to spread it evenly. th=
en
> use the flat end of my thumb along the edges to remove about 1/2"-3/4" of=
the
> material so I don't risk any falling on pots as I load. I do this on my
> advancers as well and I no longer get any of that scumming.
>
> My favorite shelves are advancers, without question. The nitride bonded c=
an
> break over cone 11, maybe even sooner. I have about four of them and thre=
e
> broke - all in the same place, around the middle.
June,
I'm always reluctant to run my hand across a used kiln shelf - just never
know what might be on there even if it looks clean - have many little scars
before I wised up.
I use Advancer shelves in my electric kiln and sprinkle alumina on them fro=
m
a small cheap kitchen sieve. It allows me to control where and how much,
also keeping it away from the edges. I do this to help the catch plates for
my crystalline glazed pots, that are made with Soldate 60, to shrink/move
easily.
Bill
--
William "Bill" Schran
wschran@cox.net
wschran@nvcc.edu
http://www.creativecreekartisans.com
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