Gail Dapogny on mon 24 jan 00
I know we've had ongoing discussions about kiln shelves, but I need some
advice for specific problems, so somewhat sheepishly I'm going to ask!
I'm in a very active potters' guild: we work together as a cooperative (own
and share materials, etc.), and fire our 70 cubic foot gas kiln about 50
times a year--cone 9-10, reduction, and we pack it. On one side of the kiln
we stack end-to-end 24 x 14 inch shelves, which suit us well and among
other things take care of long and oddly-shaped stuff.
In the old days, we had only the thick silicon carbide shelves which warped
and in some cases cracked part-way through, and in any case are just too
heavy (about 32-35 lbs-- tough for us women to lift 3-5 feet up and place
down carefully). At one point we tried the thinner (1/2 inch) sil carb
shelves which were wonderful (if expensive), but the long ones all broke.
During recent years, we've been ordering Highwater's Acme Marls which are
around 25 lbs. Their soft surface presents a problem when grinding or
chiseling off glaze spills, but we live with it and try to be careful. (We
have students, so glaze drips are a fact of life.).
However, our recent Acme Marls of that length are warping, and that's a
more serious problem. I know the best scenario would be to flip the
shelves, but we don't because of fear of flying kiln wash. At one time, we
tried Axner's lovely tough wash, but it was so tough that removing glaze
blobs was impossible without gouging the shelf in a major way. So we went
back to the usual flint/kaolin/alumina mix.
Ordering new shelves usually falls in my lap, so I'm scratching my head,
and I need to do something soon. PLEASE GIVE ME SOME ADVICE!! TIA
---GAIL
Gail Dapogny
1154 Olden Road
Ann Arbor, MI 48103-3005
(734) 665-9816
gdapogny@umich.edu
Jonathan Kaplan on tue 25 jan 00
We have used Acme Marls cordierite shelves (Remcor 1S mix) for years in our
facility both in our gas car kiln and our large front loading electric
kiln. We have not had any warping to this date. Our shelves get extremely
high usage. Periorically we do tear the car down and rebuild the deck and
shelves, but we haven't noticed any warpage.
We don't use kiln wash. It a problem for class work but we have started
using think circular slabs of clay called cookies, which we make here under
each pot just in case.
BTW, there are small circular disks of cordierite material called "setter
disks" which industry uses under ware to help with uneven or warped kiln
furniture. This might be a solution for you.
WHile yes, the cordierite surface is not as hard as silicon carbide, the
price and weight savings is enough to satisfy us!!
Best
Jonathan
Jonathan Kaplan
Ceramic Design Group LTd/Production Services
PO Box 775112
Steamboat Springs, CO 80477
(970) 879-9139 voice and fax
http://www.sni.net/ceramicdesign
UPS: 1280 13th St. Unit13
Steamboat Springs, CO 80487
Stephen Grimmer on tue 25 jan 00
Gail,
Are you posting up your shelves with three or four posts? I've found
that if you put one post at each end of a long side, and one in the middle
of the other long side, warpage is greatly reduced. Each time you load, look
down the length of each shelf as you load it and put the middle post on the
side with the warp, if any. If you already do this, ignore the above and
pretend I just gave you a dumb look!
steve
--
Steve Grimmer
Bowling Green State University
Bowling Green, OH
----------
>From: Gail Dapogny
>To: CLAYART@LSV.UKY.EDU
>Subject: shelves: quick advice badly needed
>Date: Mon, Jan 24, 2000, 1:44 PM
>
> ----------------------------Original message----------------------------
> I know we've had ongoing discussions about kiln shelves, but I need some
> advice for specific problems, so somewhat sheepishly I'm going to ask!
>
> I'm in a very active potters' guild: we work together as a cooperative (own
> and share materials, etc.), and fire our 70 cubic foot gas kiln about 50
> times a year--cone 9-10, reduction, and we pack it. On one side of the kiln
> we stack end-to-end 24 x 14 inch shelves, which suit us well and among
> other things take care of long and oddly-shaped stuff.
>
> In the old days, we had only the thick silicon carbide shelves which warped
> and in some cases cracked part-way through, and in any case are just too
> heavy (about 32-35 lbs-- tough for us women to lift 3-5 feet up and place
> down carefully). At one point we tried the thinner (1/2 inch) sil carb
> shelves which were wonderful (if expensive), but the long ones all broke.
>
> During recent years, we've been ordering Highwater's Acme Marls which are
> around 25 lbs. Their soft surface presents a problem when grinding or
> chiseling off glaze spills, but we live with it and try to be careful. (We
> have students, so glaze drips are a fact of life.).
>
> However, our recent Acme Marls of that length are warping, and that's a
> more serious problem. I know the best scenario would be to flip the
> shelves, but we don't because of fear of flying kiln wash. At one time, we
> tried Axner's lovely tough wash, but it was so tough that removing glaze
> blobs was impossible without gouging the shelf in a major way. So we went
> back to the usual flint/kaolin/alumina mix.
>
> Ordering new shelves usually falls in my lap, so I'm scratching my head,
> and I need to do something soon. PLEASE GIVE ME SOME ADVICE!! TIA
> ---GAIL
>
> Gail Dapogny
> 1154 Olden Road
> Ann Arbor, MI 48103-3005
> (734) 665-9816
> gdapogny@umich.edu
CYoung/NCzuchra on tue 25 jan 00
Gail, I haven't got an answer as I use the same shelves which you're using.
I am concerned that the product you've been using when replaced doesn't
proform the same way. Have you contacted Highwater with your problem? I'm
getting ready to replace some shelves and if warpage is a problem, I'd
rather find something else. I don't regularly flip my shelves and use no
kiln wash and have had only minute amounts of movement in the shelves after
many years.
Candace
At 02:44 PM 1/24/2000 EST, you wrote:
>----------------------------Original message----------------------------
>I know we've had ongoing discussions about kiln shelves, but I need some
>advice for specific problems, so somewhat sheepishly I'm going to ask!
>
>I'm in a very active potters' guild: we work together as a cooperative (own
>and share materials, etc.), and fire our 70 cubic foot gas kiln about 50
>times a year--cone 9-10, reduction, and we pack it. On one side of the kiln
>we stack end-to-end 24 x 14 inch shelves, which suit us well and among
>other things take care of long and oddly-shaped stuff.
>
>In the old days, we had only the thick silicon carbide shelves which warped
>and in some cases cracked part-way through, and in any case are just too
>heavy (about 32-35 lbs-- tough for us women to lift 3-5 feet up and place
>down carefully). At one point we tried the thinner (1/2 inch) sil carb
>shelves which were wonderful (if expensive), but the long ones all broke.
>
>During recent years, we've been ordering Highwater's Acme Marls which are
>around 25 lbs. Their soft surface presents a problem when grinding or
>chiseling off glaze spills, but we live with it and try to be careful. (We
>have students, so glaze drips are a fact of life.).
>
>However, our recent Acme Marls of that length are warping, and that's a
>more serious problem. I know the best scenario would be to flip the
>shelves, but we don't because of fear of flying kiln wash. At one time, we
>tried Axner's lovely tough wash, but it was so tough that removing glaze
>blobs was impossible without gouging the shelf in a major way. So we went
>back to the usual flint/kaolin/alumina mix.
>
>Ordering new shelves usually falls in my lap, so I'm scratching my head,
>and I need to do something soon. PLEASE GIVE ME SOME ADVICE!! TIA
>---GAIL
>
>Gail Dapogny
>1154 Olden Road
>Ann Arbor, MI 48103-3005
>(734) 665-9816
>gdapogny@umich.edu
>
>
Mark Fitzgerald & Wynn Fitzgerald on tue 25 jan 00
Gail,
I don't know if the thinner (1/2") silicon carbide shelves you used are
the nitride bonded ones or not. If so I would be very interested to know how
and why they broke. Was the breakage due to impact or as a result of firing?
I know of several potters who are using what are called "Advancers",
which are made by Norton and are only 5/16'" thick, yet very strong and very
light weight. I'm about to put them to use in my kiln which is a 140 cubic
ft. car kiln. My configuration calls for shelves that are 21" square. They
weigh only 14 lbs. each but are very expensive ( app. $195.00/ shelf ).
I was also looking for an alternative to the thicker silicon carbides and the
Acme Marls shelves. I have experienced severe warping and the softening of
the surface, to which you referred, with the Acme Marls. Not to mention the
40 lbs. per shelf.
I'm hopeful that these "Advancers" are the answer to my problem, and from
discussions I've had with those that have been using them, all reports are
positive.
Although it's a significant investment, ( I need 44 of them ) if they
perform like they are reported to, it will have been well worth it. The extra
stacking space per firing ( 5/16" as opposed to 1" ) will hasten the recovery
of the initial investment.
I expect to have these shelves in service in about 3 weeks and can tell
you more about them after I have used them a couple of times.
In the meantime, you can get information on them from:
Fire Brick Supply Company
1407 Marshall Ave.
St. Paul, MN 55104
800.444.3301 ext. 123 or 127
Ask to speak to Dona Turbes. If you want the names of some of the folks I
know that are using them, e-mail me off list.
Good luck.
Mark Fitzgerald
Peter Jones on tue 25 jan 00
Gail: I'm not sure exactly what advice you are looking for in regards to
kiln shelves. Is it that you want to stop the warping? Are you looking for
where to buy shelves? Looking for a good kiln wash?
As for warping, I wonder if you are bisque firing in your gas kiln. If so,
that is a possible source of warpage, not the higher firings of glazed ware.
I used to fire both bisque and glaze in the same kiln, a real pain since it
took a long time to load and unload and stack the door. About 12 years ago,
I bought a used electric kiln strictly for bisque firing. Much easier to
load and unload, less of a pain, etc. Once I did this, I noticed that my
silicon carbide kiln shelves stopped warping all together. They used to
beforehand, but in the twelve or so years since I stopped bisquing in the
gas kiln, not a single one has warped. My shelves are only kiln washed on
one side (I mix 30% EPK and 70% alumina hydrate for my wash) and I don't
flip them as a result. For that matter, I don't even alternate the position
of the posts in the firings. No need to, it seems.
The only thing I can think of to explain it is that I have heard that
silicon carbide shelves actually increase their strength during the firing
and are at their strongest at glaze temperatures. If you are only firing
them to bisque temps, they aren't as strong as at higher temps and thus may
be more prone to warping. I know, it makes no sense to me either, but I can
only go on what I see happening. You can still sight a plumb-line along my
shelves.
As for where to get them, I am at somewhat of a loss. I believe that
Newcastle Refractories in western Pennsylvania is one manufacturer that is
relatively close. There may be others nearer you.
Back in the good old days, we used to stop by the Carborundum Co
refractories plant in New Jersey and rummage through the piles of seconds.
These shelves were either over runs or had hairline cracks that they
couldn't sell on the open market for industry. But they were perfect for
studio potters. You never knew what you might find there, but if you
dropped in at the right time, you could find something that would work. The
best thing was the price: you could pick up nearly any size shelf for $5
each (yes, that's five dollars). Anyone who used to stop by there will
remember Charlie Hamoki as the man to see. Of course I don't think any of
the cash that I paid for those shelves ever went any farther than Charlie's
pocket, but who am I to complain.
Actually, my one complaint is that Carborundum was sold out to St Gobain
Refractories about a year or so ago and the plant in NJ is no longer in
existence. All the equipment, kilns, kiln shelves, everything was either
dismantled, sold off or shipped to Worcester, Mass where St G has taken over
the Norton Refractories company. It was the end of an era......
Peter Jones
Dave Finkelnburg on tue 25 jan 00
Gail,
I can't offer advice on shelf brands--fire to cone 6R only so far, using
cheap shelves from California. If you want to talk with them, call Thorley
Refractories, Inc.
11616 Center Street
South Gate, CA 90280
310-633-2647
However, I'd strongly suggest getting the silica out of your kiln wash.
Test out some 80% alumina hydrate, 10% EPK, 10% Ball Clay, 1% bentonite.
This is Ron Roy's recipe. He sprays it on with a simple garden sprayer.
The pebbly sprayed surface is helpful. Do need to screen the mixed wash
before use. I have found it works much better than the old wash I used
which had silica in the shelves. That stuff flaked in spots, stuck to the
shelves, and fused to any glaze drips such that it fused to the shelf and
took off a chunk of it, too, when I had a drip. This comes away cleaner and
is removable if I want to flip a shelf, but I have had no problems with
unwanted flaking of this shelf wash. I spend a lot less time on kiln wash
now.
Don't take my word for it, though. Just try a different wash. There
are several others out there recommending mostly alumina, remainder EPK
washes.
I really do think you need to be flipping those shelves if you want them
to last a while.
Good luck!
Dave Finkelnburg
-----Original Message-----
From: Gail Dapogny
To: CLAYART@LSV.UKY.EDU
Date: Monday, January 24, 2000 12:45 PM
Subject: shelves: quick advice badly needed
----------------------------Original message----------------------------
I know we've had ongoing discussions about kiln shelves, but I need some
advice for specific problems, so somewhat sheepishly I'm going to ask!
I'm in a very active potters' guild: we work together as a cooperative (own
and share materials, etc.), and fire our 70 cubic foot gas kiln about 50
times a year--cone 9-10, reduction, and we pack it. On one side of the kiln
we stack end-to-end 24 x 14 inch shelves, which suit us well and among
other things take care of long and oddly-shaped stuff.
In the old days, we had only the thick silicon carbide shelves which warped
and in some cases cracked part-way through, and in any case are just too
heavy (about 32-35 lbs-- tough for us women to lift 3-5 feet up and place
down carefully). At one point we tried the thinner (1/2 inch) sil carb
shelves which were wonderful (if expensive), but the long ones all broke.
During recent years, we've been ordering Highwater's Acme Marls which are
around 25 lbs. Their soft surface presents a problem when grinding or
chiseling off glaze spills, but we live with it and try to be careful. (We
have students, so glaze drips are a fact of life.).
However, our recent Acme Marls of that length are warping, and that's a
more serious problem. I know the best scenario would be to flip the
shelves, but we don't because of fear of flying kiln wash. At one time, we
tried Axner's lovely tough wash, but it was so tough that removing glaze
blobs was impossible without gouging the shelf in a major way. So we went
back to the usual flint/kaolin/alumina mix.
Ordering new shelves usually falls in my lap, so I'm scratching my head,
and I need to do something soon. PLEASE GIVE ME SOME ADVICE!! TIA
---GAIL
Gail Dapogny
1154 Olden Road
Ann Arbor, MI 48103-3005
(734) 665-9816
gdapogny@umich.edu
David Woodin on tue 25 jan 00
Coating new shelves with ITC 100 will allow you to turn the shelves without
anything dropping off them, the shelves also will not warp as much. If glaze
drips on the ITC 100 you have to knock it off as usual and retouch the spot.
David
Gail Dapogny on wed 26 jan 00
Thanks Peter...
No, we don't bisque fire those shelves or even bisque fire in the same
kiln. We have a second smaller old gas kiln we bisque fire in.
I am interested in alternative kiln washes, but also at the moment I'm
looking for a source of light to middle weight (not sil carb weight)
shelves that don't warp so readily.Our old Sil Carb shelves are from
Newcastle.
---Gail
Gail Dapogny
1154 Olden Road
Ann Arbor, MI 48103-3005
(734) 665-9816
gdapogny@umich.edu
David McDonald on wed 26 jan 00
Mark,
I've been using 1/2" X 14" X 28" nitrite bonded silicon carbide shelves
for about 5 years now, firing to cone 10 with a significant load on them
(up to 25 pounds). These shelves were over $100 each at the time(inc.
shipping), and I sure had my doubts about them. They've held up great
(still blows my mind, because of how thin they are), and the only one
I've lost so far was the one that snapped in two when I tapped it in the
middle to settle it into the wadding (whoops, duh!). Now when I hear you
talking about 5/16" !!! shelves, I am astounded! How could they possibly
hold up over time at those temperatures? What will you be firing them to?
PLEASE let us know when you can see how well they are working for you.
THANKS! David McDonald
Original message----------------------------
> Gail,
> I don't know if the thinner (1/2") silicon carbide shelves you
> used are
> the nitride bonded ones or not. If so I would be very interested to
> know how
> and why they broke. Was the breakage due to impact or as a result of
> firing?
> I know of several potters who are using what are called
> "Advancers",
> which are made by Norton and are only 5/16'" thick, yet very strong
> and very
> light weight. I'm about to put them to use in my kiln which is a 140
> cubic
> ft. car kiln. My configuration calls for shelves that are 21"
> square. They
> weigh only 14 lbs. each but are very expensive ( app. $195.00/ shelf
> ).
> I was also looking for an alternative to the thicker silicon
> carbides and the
> Acme Marls shelves. I have experienced severe warping and the
> softening of
> the surface, to which you referred, with the Acme Marls. Not to
> mention the
> 40 lbs. per shelf.
> I'm hopeful that these "Advancers" are the answer to my problem,
> and from
> discussions I've had with those that have been using them, all
> reports are
> positive.
> Although it's a significant investment, ( I need 44 of them ) if
> they
> perform like they are reported to, it will have been well worth it.
> The extra
> stacking space per firing ( 5/16" as opposed to 1" ) will hasten the
> recovery
> of the initial investment.
> I expect to have these shelves in service in about 3 weeks and
> can tell
> you more about them after I have used them a couple of times.
> In the meantime, you can get information on them from:
> Fire Brick Supply Company
> 1407 Marshall Ave.
> St. Paul, MN 55104
> 800.444.3301 ext. 123 or 127
> Ask to speak to Dona Turbes. If you want the names of some of
> the folks I
> know that are using them, e-mail me off list.
> Good luck.
>
> Mark Fitzgerald
________________________________________________________________
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Hank Murrow on thu 27 jan 00
Hello Group: I've been using the Crystar 5/16" x 14" x 28"
Nitride-bonded Silicon carbide setters for about eight years now. I rolled
on(paint roller, medium nap) a thinnish coat of wash; and each fire I
spread on a dusting of alumina powder. Not one has warped, not even a
little bit. I fire to C/11 both in OX and heavy RED. Just received two
Advancer shelves, as the Crystars are priced out of sight (Circa $260); but
I can't report on them as yet. Hank in Eugene
>----------------------------Original message----------------------------
>Mark,
> I've been using 1/2" X 14" X 28" nitrite bonded silicon carbide
>shelves
>for about 5 years now, firing to cone 10 with a significant load on them
>(up to 25 pounds). These shelves were over $100 each at the time(inc.
>shipping), and I sure had my doubts about them. They've held up great
>(still blows my mind, because of how thin they are), and the only one
>I've lost so far was the one that snapped in two when I tapped it in the
>middle to settle it into the wadding (whoops, duh!). Now when I hear you
>talking about 5/16" !!! shelves, I am astounded! How could they possibly
>hold up over time at those temperatures? What will you be firing them to?
>PLEASE let us know when you can see how well they are working for you.
>THANKS! David McDonald
>
>Original message----------------------------
>> Gail,
>> I don't know if the thinner (1/2") silicon carbide shelves you
>> used are
>> the nitride bonded ones or not. If so I would be very interested to
>> know how
>> and why they broke. Was the breakage due to impact or as a result of
>> firing?
>> I know of several potters who are using what are called
>> "Advancers",
>> which are made by Norton and are only 5/16'" thick, yet very strong
>> and very
>> light weight. I'm about to put them to use in my kiln which is a 140
>> cubic
>> ft. car kiln. My configuration calls for shelves that are 21"
>> square. They
>> weigh only 14 lbs. each but are very expensive ( app. $195.00/ shelf
>> ).
>> I was also looking for an alternative to the thicker silicon
>> carbides and the
>> Acme Marls shelves. I have experienced severe warping and the
>> softening of
>> the surface, to which you referred, with the Acme Marls. Not to
>> mention the
>> 40 lbs. per shelf.
>> I'm hopeful that these "Advancers" are the answer to my problem,
>> and from
>> discussions I've had with those that have been using them, all
>> reports are
>> positive.
>> Although it's a significant investment, ( I need 44 of them ) if
>> they
>> perform like they are reported to, it will have been well worth it.
>> The extra
>> stacking space per firing ( 5/16" as opposed to 1" ) will hasten the
>> recovery
>> of the initial investment.
>> I expect to have these shelves in service in about 3 weeks and
>> can tell
>> you more about them after I have used them a couple of times.
>> In the meantime, you can get information on them from:
>> Fire Brick Supply Company
>> 1407 Marshall Ave.
>> St. Paul, MN 55104
>> 800.444.3301 ext. 123 or 127
>> Ask to speak to Dona Turbes. If you want the names of some of
>> the folks I
>> know that are using them, e-mail me off list.
>> Good luck.
>>
>> Mark Fitzgerald
>
>________________________________________________________________
>YOU'RE PAYING TOO MUCH FOR THE INTERNET!
>Juno now offers FREE Internet Access!
>Try it today - there's no risk! For your FREE software, visit:
>http://dl.www.juno.com/get/tagj.
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