Alex Solla on fri 15 dec 06
We fire to cone 5/6 almost every other day (10cu ft L&L)
and I can say with some level of certainty that after about 6 months of
abuse...
or roughly 100-150 firings, even kiln wash of 50EPK/50Alumina Hydrate
starts to act like a sponge and absorbs some of the glaze vapors.
Just had one shelf go in same as always, nice and pretty and came out with
lots of plucking... too many firings on that coat of wash. A quick spray
of kiln wash and all was nice and happy again.
Good luck finding an "ideal" wash. There's always some compromise.
cheers,
Alex Solla
Cold Springs Studio Pottery
4088 Cold Springs Road
Trumansburg, NY 14886
607-387-4042 voice/fax
www.coldspringsstudio.com
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG]On Behalf Of Ann Brink
Sent: Friday, December 15, 2006 1:37 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: kiln wash
GOOD THING YOU ASKED!
For years I used 50/50 Epk and silica. That might have been ok for
earthenware temps, but I fired to cone 7/8 and after a while it all turned
glassy...impossible to chip off too. I think glaze vapors fluxed it.
At some point I got new shelves for my Skutt 1027 and used a wash of 50/50
Epk and alumina hydrate. What a difference! Not a sign of glassiness, and
if something drips, it chips off easily. Sometimes I brush more over some
spots of glaze as a barrier. Works great.
Ann Brink in Lompoc CA
(mostly about pottery)
Subject: Re: kiln wash
> While we are talking recipes, Is there a difference in
> the kiln wash used at different temps? And if there is
> what is the temp/ recipe change?
>
> Fran
>
>
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jonathan edward byler on fri 15 dec 06
We have been using a rough mix of epk, alumina hydrate, and silica in
equal parts by volume (4 scoops each into 5 gallon bucket + water.
Seems to work pretty well. Probably could be better. All but the
most serious runs come loose without taking up chunks of shelf or
breaking the pots. I prefer to use caution in loading and leave
nasty runny looking glaze jobs out or on a scrap piece of kiln shelf
(or bisqued tile), rather than stress too much about the kiln wash
composition. We have a whole shelf in the glaze room that is
purgatory for badly glazed pots... seems to work better than
anything at keeping the shelves clean. The students with badly
glazed items who want their work fired eventually find their pots in
purgatory and get the obligatory repeat lessons on how to glaze
properly. They may act like children sometimes, but they are all way
too old for me to wipe their bottoms anymore ;-) When the wash gets
on really thick and starts to flake after a while, I get out the
little angle grinder and make white clouds outside. Those concrete
scraper blocks work fine too, just takes a bit longer. by the way,
we fire to cone 9-10.
jon byler
3-D Building Technician
Art Department
Auburn University
Auburn, AL 36849
On Dec 15, 2006, at 2:39 PM, Alex Solla wrote:
> We fire to cone 5/6 almost every other day (10cu ft L&L)
> and I can say with some level of certainty that after about 6
> months of
> abuse...
> or roughly 100-150 firings, even kiln wash of 50EPK/50Alumina Hydrate
> starts to act like a sponge and absorbs some of the glaze vapors.
> Just had one shelf go in same as always, nice and pretty and came
> out with
> lots of plucking... too many firings on that coat of wash. A quick
> spray
> of kiln wash and all was nice and happy again.
>
> Good luck finding an "ideal" wash. There's always some compromise.
>
> cheers,
> Alex Solla
>
> Cold Springs Studio Pottery
> 4088 Cold Springs Road
> Trumansburg, NY 14886
>
> 607-387-4042 voice/fax
> www.coldspringsstudio.com
>
>
>
>
> -----Original Message-----
> From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG]On Behalf Of Ann Brink
> Sent: Friday, December 15, 2006 1:37 PM
> To: CLAYART@LSV.CERAMICS.ORG
> Subject: Re: kiln wash
>
>
> GOOD THING YOU ASKED!
>
> For years I used 50/50 Epk and silica. That might have been ok for
> earthenware temps, but I fired to cone 7/8 and after a while it all
> turned
> glassy...impossible to chip off too. I think glaze vapors fluxed it.
>
> At some point I got new shelves for my Skutt 1027 and used a wash
> of 50/50
> Epk and alumina hydrate. What a difference! Not a sign of
> glassiness, and
> if something drips, it chips off easily. Sometimes I brush more
> over some
> spots of glaze as a barrier. Works great.
>
> Ann Brink in Lompoc CA
> (mostly about pottery)
>
> Subject: Re: kiln wash
>
>
>> While we are talking recipes, Is there a difference in
>> the kiln wash used at different temps? And if there is
>> what is the temp/ recipe change?
>>
>> Fran
>>
>>
>
> _______________
Ivor and Olive Lewis on sun 17 dec 06
Dear Alex Solla,=20
An interesting observation.=20
Have you noticed any change in the tactile property of the well fired =
kiln wash. Has the surface taken on a coarse texture over the smooth =
texture of the original application? Are the interiors of your kilns =
given a coating of this was?
Best regards,
Ivor Lewis.
Redhill,
South Australia.
Alex Solla on sun 17 dec 06
Morning Ivor-
Comparing fresh wash (sprayed) to old wash... I would say that there is
definitely a difference in texture. The older the wash gets
the more rough, and uneven... though not because of flaking or multiple
layers. Despite most folks' protestations, I think it very worthwhile
to grind wash off once a year, wash the shelf, and then apply fresh wash,
nice and smooth.
Nothing is sprayed on the inside of my kilns.
cheers,
Alex Solla
Trumansburg, NY
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG]On Behalf Of Ivor and
Olive Lewis
Sent: Saturday, December 16, 2006 10:24 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Re: kiln wash 50EPK/50Alumina Hydrate
Dear Alex Solla,
An interesting observation.
Have you noticed any change in the tactile property of the well fired kiln
wash. Has the surface taken on a coarse texture over the smooth texture of
the original application? Are the interiors of your kilns given a coating of
this was?
Best regards,
Ivor Lewis.
Redhill,
South Australia.
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Ivor and Olive Lewis on tue 19 dec 06
Dear Alex Solla,=20
An interesting observation. Thank you for your information.
One of the features of maintaining such a mixture at elevated =
temperatures over a period of time, even intermittently, is potential =
for the larger grains of a mineral to grow larger at the expense of the =
smaller ones which diminish in size until they disappear. Given that =
Kaolin will decompose when it is first heated above about 1000 deg C and =
solid state reactions will happen as the temperature rises beyond that.
So it could be that your coating at the end of a years service is high =
grade Mullite.
Best regards,
Ivor.
Alex Solla on tue 19 dec 06
Interesting idea Ivor. Certainly wouldnt surprise me.
I guess I look at clay/glaze problems from a very low tech angle before
hitting Parmelee/Hamer etc for answers.
I see the kiln wash much like a sponge, dry it behaves like a dry sponge.
Nothing is
absorbed. But with time, and vapors from glaze, I think it begins to "wet"
from the
inside. The flakes of wash become glassy and brittle. And then I begin to
see plucking as the wash
starts to bond with the claybody (Tucker's Smooth White stoneware c6). Some
part of me wishes I could send them
off to be examined more thoroughly... another part of me wishes I had more
time
to make pots. Hmmm. Guess which one wins out today?
Thanks for the mullite ideas. Will keep ruminating on this over the winter.
cheers,
Alex
_____________________
Alex Solla
Cold Springs Studio Pottery
4088 Cold Springs Road
Trumansburg, NY 14886
607-387-4042 voice/fax
www.coldspringsstudio.com
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG]On Behalf Of Ivor and
Olive Lewis
Sent: Tuesday, December 19, 2006 12:17 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: kiln wash 50EPK/50Alumina Hydrate
Dear Alex Solla,
An interesting observation. Thank you for your information.
One of the features of maintaining such a mixture at elevated temperatures
over a period of time, even intermittently, is potential for the larger
grains of a mineral to grow larger at the expense of the smaller ones which
diminish in size until they disappear. Given that Kaolin will decompose when
it is first heated above about 1000 deg C and solid state reactions will
happen as the temperature rises beyond that.
So it could be that your coating at the end of a years service is high grade
Mullite.
Best regards,
Ivor.
____________________________________________________________________________
__
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.
Ivor and Olive Lewis on thu 21 dec 06
Dear Alex Solla ,
Another factor I forgot to mention was that as this transformation =
proceeds open gaps, voids between particles of the "Sponge" migrate and =
diminish is size.
I know I have played this record many times before but Kingery et al, =
"Introduction to Ceramics" Ch Ten, "Grain Growth, Sintering and =
Vitrification" gives far better insights into the way our raw materials =
behave than any of the more popular texts people speak of from time to =
time.
Enjoy your holiday.
Best regards,
Ivor Lewis.
Redhill,
South Australia.
Craig Martell on sat 23 dec 06
Hello Kiln Washers:
I've never been able to figger out why folks like alumina hydrate so
much. Oh, I just remembered that it's cheaper than alumina oxide which is
basically just calcined alumina.
If you calculate the "loss on ignition" of a kaolin/alumina hydrate blend,
it comes to about 48% LOI. You lose about 36% from the alumina plus about
13% from the kaolin.
Anyway, I use 75% alumina oxide plus 25% Kingsley Kaolin for my wash. I
has good bonding properties so it doesn't flake off the shelves and a lower
LOI and shrinkage so it's denser in the fired state. I rewash about once a
year. The wash is used on Crystars and Advancers plus high alumina plate
and bowl setters. Works fine on all of that stuff. I remove the old wash
with an angle grinder with a wire brush head attached. The old wash comes
off very quickly.
If you do a cost analysis on Hydrate and Alumina Ox and the amount of
alumina each contributes after firing they are about the same cost.
for what it's worth, Craig Martell Hopewell, Oregon
jonathan edward byler on sat 23 dec 06
how well do the pots come off the shelves with a glaze run?
On Dec 23, 2006, at 11:56 AM, Craig Martell wrote:
> Hello Kiln Washers:
>
> I've never been able to figger out why folks like alumina hydrate so
> much. Oh, I just remembered that it's cheaper than alumina oxide
> which is
> basically just calcined alumina.
>
> If you calculate the "loss on ignition" of a kaolin/alumina hydrate
> blend,
> it comes to about 48% LOI. You lose about 36% from the alumina
> plus about
> 13% from the kaolin.
>
> Anyway, I use 75% alumina oxide plus 25% Kingsley Kaolin for my
> wash. I
> has good bonding properties so it doesn't flake off the shelves and
> a lower
> LOI and shrinkage so it's denser in the fired state. I rewash
> about once a
> year. The wash is used on Crystars and Advancers plus high alumina
> plate
> and bowl setters. Works fine on all of that stuff. I remove the
> old wash
> with an angle grinder with a wire brush head attached. The old
> wash comes
> off very quickly.
>
> If you do a cost analysis on Hydrate and Alumina Ox and the amount of
> alumina each contributes after firing they are about the same cost.
>
> for what it's worth, Craig Martell Hopewell, Oregon
>
> ______________________________________________________________________
> ________
> 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.
Craig Martell on thu 28 dec 06
At 04:44 PM 12/23/2006 -0600, you wrote:
>how well do the pots come off the shelves with a glaze run?
Hi:
That depends on the kind of shelves you use, how hot you are firing, and
how bad the glaze run is. Basically, this is a good, refractory, high fire
wash and it will protect your shelves very well. My feeling is that
nothing can save a shelf from the worst case scenario. I don't get much
glaze sticking to the shelf so I can't comment about huge runs. I mainly
use shelf wash to prevent plucking, which is chunks of the foot sticking to
the shelf and popping off the pot as you remove it from the shelf.
regards, Craig Martell Hopewell, Oregon
Ivor and Olive Lewis on sat 30 dec 06
Dear Craig Martell,
A Happy New Year to you.
Know what you mean about modern telephony. My Mobile went down a few =
weeks ago. No problem with the battery. So I got through to services and =
faults via copper wire. a couple of ticks later and a friendly voice =
told me that the repeater was down for service,
Good service, fifteen years from that mixture as bedding for a bag wall =
is amazing.
When I was salt glazing I used coarse softener salt, about 1/4 inch =
crystals. This exploded and then quickly melted. I never seemed to get =
any slagging in the fire channels.
Not fired that kiln in over fifteen years, but I have thought of =
converting it to Wood firing. The trees I planted half a life time ago =
are beginning to throw down a lot of trash and it is becoming a bush =
fire hazard. It will just require a minor rebuild with a good fire box.
Keep well and creative.
Best regards,
Ivor
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