Jeff Kirk on wed 13 mar 96
----------------------------Original message----------------------------
I would never suggest using moist wads of clay to level-separate posts from
shelves. There is a strong possibility that if the kiln is pre-heated to
rapidly, the clay wads will explode. The result being apon unloading one's
kiln, discovering pieces of vitrified clay inside many lovely pots ( always
the nicest ones; remember, MURPHY's LAW never sleeps!). I would suggest using
extra pieces of a Fiber-fax material to separate-level one's shelves. I think
most potter's have learned to live with cracked shelves, if used and loaded
properly they will last for a VERY long time. J. Kirk, Glen Echo Pottery
Richard C. Aerni on thu 14 mar 96
At 10:45 PM 3/13/96 EST, you wrote:
>----------------------------Original message----------------------------
>----------------------------Original message----------------------------
>I would never suggest using moist wads of clay to level-separate posts from
>shelves. There is a strong possibility that if the kiln is pre-heated to
>rapidly, the clay wads will explode. The result being apon unloading one's
>kiln, discovering pieces of vitrified clay inside many lovely pots ( always
>the nicest ones; remember, MURPHY's LAW never sleeps!). I would suggest using
>extra pieces of a Fiber-fax material to separate-level one's shelves. I think
>most potter's have learned to live with cracked shelves, if used and loaded
>properly they will last for a VERY long time. J. Kirk, Glen Echo Pottery
>
>
I've used moist wads of clay to level and separate posts from shelves in the
kiln for 20 years and have never had one explode or cause a problem. Then
again, I also candle the kiln for a couple of hours, and then take it up
slowly.
As for types of kiln shelves, I've also used both silicon carbide and the
dry pressed high alumina ones side by side over the last ten years. Both
are still functioning, but the dry pressed HA ones are flatter and in better
shape than the silicon carbide. Also cost half as much. They are also far
less likely to crack due to thermal stress or thermal shock.
Richard
2975 County Road 40
Bloomfield, NY 14469
Phone (716) 657-6045
Fax (716) 657-6023 call before faxing
email rcaerni@cyber1.servtech.com
"...if it don't kill me, I'll be a better man for it..."
Ron Roy on thu 14 mar 96
Hello all,
I am sure there will be more on this but here is my experience. I have used
4 stilts, leveled with wads, for large platters on and off for 30 years and
have never had any explode. I DO FIRE SLOWELY - pilots on over night - but
there were times in art college when we went as fast as possible. I suppose
I should add - the right kind of clay would have plenty of grog, granular
kyanite, silica sand - what ever, to make sure the water can get out easy.
I also seem to remember some cauction about firing shelves for the first
time - making sure all the moisture was out or there would be cracking. I
can't remember which kind of sheves that advice was for.
RR
Dave Eitel on thu 14 mar 96
>----------------------------Original message----------------------------
>----------------------------Original message----------------------------
>I would never suggest using moist wads of clay to level-separate posts from
>shelves. There is a strong possibility that if the kiln is pre-heated to
>rapidly, the clay wads will explode. The result being apon unloading one's
>kiln, discovering pieces of vitrified clay inside many lovely pots ( always
>the nicest ones; remember, MURPHY's LAW never sleeps!). I would suggest using
>extra pieces of a Fiber-fax material to separate-level one's shelves. I think
>most potter's have learned to live with cracked shelves, if used and loaded
>properly they will last for a VERY long time. J. Kirk, Glen Echo Pottery
I've been using heavily grogged wet clay on my kiln posts for years and
have never had one blow up. If you're not firing fast enough to blow up
your cone pats, the wads won't blow either. The wet wads give a wonderful
seat to the shelves and there is never any wobble in a stack of shelves.
Dave...waiting patiently for over-the-counter rogaine
Dave Eitel
Cedar Creek Pottery
Cedarburg, WI
daveitel@execpc.com
Eric Lindgren on thu 14 mar 96
>I would never suggest using moist wads of clay to level-separate posts from
>shelves. There is a strong possibility that if the kiln is pre-heated to
>rapidly, the clay wads will explode. The result being apon unloading one's
>kiln, discovering pieces of vitrified clay inside many lovely pots ( always
>the nicest ones; remember, MURPHY's LAW never sleeps!). I would suggest using
>extra pieces of a Fiber-fax material to separate-level one's shelves. I think
>most potter's have learned to live with cracked shelves, if used and loaded
>properly they will last for a VERY long time. J. Kirk, Glen Echo Pottery
I agree about the danger of exploding wads. So I use a mix of alumina
hydrate and XXSagger, 50/50. This wadding dries quickly (due to the
grog-like effect of the alumina), so is less likely to explode and can be
easily removed from post ends.
Eric Lindgren
lindgren@muskoka.com
___________________________________________________________________________
DZeigfinge@aol.com on thu 14 mar 96
The key words here are: Pre-heat slowly. Re: using moist clay wading on your
posts/shelves. With a goodly number of firings and experience---no problem.
Again ,I would never suggest using this method to someone just getting
started. Also, one has to be careful about the type of clay when wading.
There is a problem when the clay wad fuses to the post and/or the shelf. the
vitrified wad in most cases has to be ground off( Lots of fun,for those of
you w/ Milwakee Grinders I might add.) J. Kirk, Glen Echo Pottery "
Remember: just floss the the one's you want to keep"
D. Stuchbery on fri 15 mar 96
----------------------------Original message----------------------------
On Fri, 8 Mar 1996, Malcolm Davis wrote:
> ----------------------------Original message----------------------------
> Has anyone out there had recent trouble with silicon carbide shelves (New
> Castle Refractories) cracking during firing?
I don't know if it is of any help or not, but when I returned to
Australia and set up my own pottery in the late seventies, I purchased
Silicon Carbide shelves, having observed the success David Eeles had with
them in the U.K..
I was told by other potters at the time that, that due to a change of the
source of supply of carborundum to expect the newer shelves to crack.
(This is almost twenty years ago).
Someone told me that in order to prevent this happening, fire the Silicon
Carbide shelves on their edge in a totally OXIDIZING atmospere to 1300
degrees centigrade. I did this in an electric kiln, as close as to 1300
as I could.
It may have no scientific relevance, but when you have paid out so much
money for what are supposed to be a superior product, you will try
anything to insure their longevity.
I still use the same shelves 21"x16" in very heavy reduction firings to cone
10, none have cracked, and all are reasonably straight, considering the
number of firings they have done. I can't say for sure as to whether that
initial oxidizing firing helped, but hopefully I will still have these
shelves for a long time yet.
David Stuchbery.
Dave Eitel on fri 15 mar 96
>----------------------------Original message----------------------------
>The key words here are: Pre-heat slowly. Re: using moist clay wading on your
>posts/shelves. With a goodly number of firings and experience---no problem.
>Again ,I would never suggest using this method to someone just getting
>started. Also, one has to be careful about the type of clay when wading.
>There is a problem when the clay wad fuses to the post and/or the shelf. the
>vitrified wad in most cases has to be ground off( Lots of fun,for those of
>you w/ Milwakee Grinders I might add.) J. Kirk, Glen Echo Pottery "
>Remember: just floss the the one's you want to keep"
LOTS of grog in the wadding helps prevent sticking. I have also brushed a
bit of kiln wash on the shelf to keep wads from sticking. They usually pop
off more easily when they're cold. Sometimes I have to help one off with a
tap from a hammer and cold chisel, but the grog and kiln wash work 99% of
the time.
Dave...waiting patiently for over-the-counter rogaine
Dave Eitel
Cedar Creek Pottery
Cedarburg, WI
daveitel@execpc.com
Richard C. Aerni on sat 16 mar 96
At 05:49 PM 3/15/96 EST, you wrote:
>----------------------------Original message----------------------------
>>----------------------------Original message----------------------------
>>The key words here are: Pre-heat slowly. Re: using moist clay wading on your
>>posts/shelves. With a goodly number of firings and experience---no problem.
>>Again ,I would never suggest using this method to someone just getting
>>started. Also, one has to be careful about the type of clay when wading.
>>There is a problem when the clay wad fuses to the post and/or the shelf. the
>>vitrified wad in most cases has to be ground off
>
>
>LOTS of grog in the wadding helps prevent sticking. I have also brushed a
>bit of kiln wash on the shelf to keep wads from sticking. They usually pop
>off more easily when they're cold. Sometimes I have to help one off with a
>tap from a hammer and cold chisel, but the grog and kiln wash work 99% of
>the time.
>
>
I just keep a jar of alumina hydrate handy when I load the kiln. I roll out
the little wet clay balls, and before setting on the shelf posts, roll them
in the alumina powder, tap off the excess, and voila! After firing, they
can just be lifted off the post...no sticking.
Richard
2975 County Road 40
Bloomfield, NY 14469
Phone (716) 657-6045
Fax (716) 657-6023 call before faxing
email rcaerni@cyber1.servtech.com
"...if it don't kill me, I'll be a better man for it..."
Leonard Smith on sat 16 mar 96
>----------------------------Original message----------------------------
>I've used moist wads of clay to level and separate posts from shelves in the
>kiln for 20 years and have never had one explode or cause a problem. Then
>again, I also candle the kiln for a couple of hours, and then take it up
>slowly.
We make our wadding clay from 50% fine sand(65#) and 50% white ball clay
all by vollume and they have never blown up even when fired up to 200 in 2
hrs straight after packing. For cone pats I use a skewer to make holes all
through the thickest bits and they are also fine from the same mix.
As for props I always used to use 3 but now on our 24 x 12 shelves prefer
to use 4 as I feel more in control of the warping. With 4 the shelf warps
slightly in the middle and i turn it oever in the next firing and it
returns to normal. With 3 props the edge between the two props dips down
and the cornes not supported on the other side drop too. Even turning this
around never seemed to even the shelf out. So we have come to the 4 prop
conclusion with wadding to ensure the shelf sits evenly. This only applies
to our cone 11 reduction firings we use 3 props everywhere else.
---------------------------------------------------------------------------
Leonard Smith ARCADIA STUDIOS Email: smithl@ozemail.com.au
10 Marrakesh Place
Arcadia, 2159, NSW, Australia. Phone 61 2 653 2507
---------------------------------------------------------------------------
Kathi LeSueur on sun 30 may 04
Has anyone else experienced cracking of Thorley kiln shelves since
Laguna took over the company? I've used Thorley shelves since 1976,
firing to flat cone 10 until the past couple of years when I lowered the
temp to Cone 9 . I've never had a problem with the shelves until now.
I purchase twenty 15x24x7/8 shelves in January. Of those, eight are
still unused. Of the twelve I have used, nine have cracked on the first
firing. Each 13 1/2 inches from the edge on the long side and the crack
is identical in nature. This is not a spot where there was a post and
the only items fired on the shelves were thin slab pieces. I have
shelves from 1991 that still have no signs of cracking and have been
fired about 35 times a year. So, this problem is really disturbing.
I called Laguna and gave them lots of information several weeks ago.
They said they'd get back to me. Since then I've been ignored. Customer
service is always tied up and my messages go unreturned. I had thought
that Laguna had a better reputation than this.
Kathi
Donald G. Goldsobel on mon 31 may 04
----- Original Message -----
From: "Kathi LeSueur"
To:
Sent: Sunday, May 30, 2004 6:03 PM
Subject: cracking shelves
Kathi,
I have used Thorley shelves for a very long time and never had a problem.I
would demand a full refund and return the shelves. Even if there is no
change in production methods because of the change in ownership, there is no
excuse for such uniform failure other than a production flaw. Go the hard
route with them and threaten a small claims court action if the demand for
refund fails.
Donald
Tig Dupre on tue 1 jun 04
---------------------------<>--------------------------------------
Has anyone else experienced cracking of Thorley kiln shelves since
Laguna took over the company? I've used Thorley shelves since 1976,
firing to flat cone 10 until the past couple of years when I lowered the
temp to Cone 9 . I've never had a problem with the shelves until now.
---------------------------<>--------------------------------------
Kathi,
You are not alone. I, too have had less than sterling service from Laguna. I ordered some round shelves for my electric kiln. I wanted 19" or 20" and was assured that Thorley shelves would be able to supply what I wanted. Many weeks went by, with me bugging my local supplier to the point of distraction.
FINALLY the shelves came in. I was advised to fire them to bisque first, then coat and fire to glaze temperatures--^6 for me. Imagine my anger when after the bisque fire, one shelf had cracked badly, and all three were warped and distorted, at only ^04.
Clayart made good on the sale and exchanged the shelves for some others, but the substitutes are still not what I had wanted, or needed.
Laguna, if you're lurking out there, better pay attention! Customers are getting upset, and your reputation is suffering.
And, I am still looking for some 20" round shelves, 5/8" thick. I can get them through the same company who manufactures my kiln, but they're awfully expensive. I can use 19" and would appreciate a source fairly local to Tacoma, Washington, so I can avoid shipping.
Thanks,
Tig Dupre
in Port Orchard, Washington
Frank Bales on fri 4 jun 04
This is a neophytes question, but isn't it possible to make your own
shelves? You had to fire these anyway.
FrankB
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG]On Behalf Of Tig Dupre
You are not alone. I, too have had less than sterling service from Laguna.
I ordered some round shelves for my electric kiln. I wanted 19" or 20" and
was assured that Thorley shelves would be able to supply what I wanted.
Many weeks went by, with me bugging my local supplier to the point of
distraction.
FINALLY the shelves came in. I was advised to fire them to bisque first,
then coat and fire to glaze temperatures--^6 for me. Imagine my anger when
after the bisque fire, one shelf had cracked badly, and all three were
warped and distorted, at only ^04.
Clayart made good on the sale and exchanged the shelves for some others, but
the substitutes are still not what I had wanted, or needed.
Laguna, if you're lurking out there, better pay attention! Customers are
getting upset, and your reputation is suffering.
And, I am still looking for some 20" round shelves, 5/8" thick. I can get
them through the same company who manufactures my kiln, but they're awfully
expensive. I can use 19" and would appreciate a source fairly local to
Tacoma, Washington, so I can avoid shipping.
| |
|
