frasera1@westatpo.westat.com on fri 23 aug 96
I work in a studio with a gorgious gas reduction kiln, firing to
cone 9 or 10. The only problem is that often (painfully often) my
pots are sticking to the kiln shelves. No, I don't have a
dripping glaze problem, it just that the naked bottom of my pots
are sticking. I've lost lots of chunk of carefully carved feet
this way.
In the studio we use a "wax resist for porcelain". Its basically
normal wax resist with some chemical (was it alumina silica?)
Should I be using some other type of wax resist, or is there some
other trick here?
Alexa
Kirby Benson on sat 24 aug 96
Alexa,
Porcelain will definately stick to kiln shelves of all kinds. The
way to overcome this problem is to buy some fine mesh silica sand
from your pottery supply or a building suppy will often have it for
sand blasting. Put the sand in a salt or pepper shaker or can and
lightly sprinkle this on the shelves (carefully - so it doesn't
dribble down into the ware on the lower shelves) around where the
foot of your pot will set. This way, when the porcelain shrinks, it
rides on the layer of sand and doesn't pull pieces out of the bottom.
If your porcelain is compounded for cone9 - 10, it should be nearly
vitrious at that temp. and that is why it begins to stick to the
shelves.
Kirby Benson
DEBRA ULLAND on sat 24 aug 96
To avoid porcelain from sticking to itself (e.g. lids to jar seats) and to
kiln shelves I put alumina oxide in my wax resist. I also dust the kiln
shelves with alumina oxide or 200 mesh silica. This sticking problem never
happens in oxidation at Cone 10 only in reduction. Anyone know why????
Cathy Nelson Hartman on sat 24 aug 96
Alexa wondered about tips to keep cone 10 porcelain from sticking to the
shelves during firing. There are several possibilities. Some potters dust
a layer of aluminum hydrate or aluminum oxide on the shelf before putting
pots on it. What I use is mixing about a tablespoon and a half to a pint
of liquid wax. This I use to wax lidded pieces where I want a little
heavier layer of alumina to insure against sticking. On mugs, soup bowls,
etc., I use plain liquid wax and then rub the bottom against a layer of
alumina. Enough sticks to the wax to keep the bottoms from sticking. On
large, heavier pieces I use the use the wax/alumina mixture AND a thin
layer of alumina on the shelf under the pot.
Try to use the least alumina you can to do the job because you will
have to remove it from your pot bottom, and it gets tedious. But the
foot ( or in your case the feet) of your pot stays where you put
it.
Walter
Walter Hartman full time studio potter since 1973
cone 10 porcelain
90% functional
Hartman Pottery oxidation in gas kiln
1600 Willowwood sell all work at art fairs
Denton, TX 76205 work by myself
(817) 382-1083 BS in math('67);taught math 3 years
native Texan who doesn't own a gun
e-mail: cnh0002@jove.acs.unt.edu
LEE on sat 24 aug 96
If porcelain pots are sticking to the shelves, add alumina hydrate to
your wax. Try using about 2 or 3 teaspoons alumina per cup of liquid wax.
Try this mixture on your lids too.
Be careful not to get this on a glaze (and label it so you do not ever
use it for a wax-resist technique), unless of coarse you want a "funky"
result.
Sometimes where the glaze meets this wax, you have some minor problems.
Test it on a few pieces first.
Make sure your shelves are thoroughly kiln-washed too. You could add some
alumina to your kiln-wash formula, for added protection.
May your pots never stick again,
Lee LREXRODE@EDINBORO.edu
Dave and Pat Eitel on sat 24 aug 96
>----------------------------Original message----------------------------
> I work in a studio with a gorgious gas reduction kiln, firing to
> cone 9 or 10. The only problem is that often (painfully often) my
> pots are sticking to the kiln shelves. No, I don't have a
> dripping glaze problem, it just that the naked bottom of my pots
> are sticking. I've lost lots of chunk of carefully carved feet
> this way.
>
> In the studio we use a "wax resist for porcelain". Its basically
> normal wax resist with some chemical (was it alumina silica?)
> Should I be using some other type of wax resist, or is there some
> other trick here?
>
> Alexa
Using kiln wash would probably solve the problem. I once kept a plate with
grog next to the kiln and when I was loading I'd touch the feet of the
porcelain pots to the plate of grog. The pieces that stuck to the wax on
the foot acted as ball bearings and prevented the pots from fusing to the
shelves.
Later...Dave
Dave Eitel
Cedar Creek Pottery
Cedarburg, WI
daveitel@execpc.com
http://www.digivis.com/CedarCreek/home.html
Nils Lou on sat 24 aug 96
Porcelain does want to stick to kiln shelves, especially silicon
carbide. To prevent that I mix hydrated alumina in commercial wax resist
using it for all bottoms. I also wipe on alumina hydrate dry on the kiln
shelf surface--no kiln wash! Easily washed off if desired--shelf can be
turned over if needed. No more porcelain chunks left fused
to the shelf. Don't forget to wear your mask when you wipe
on the alumina. Wipe it in and remove any remaining loose
dust. Nils Lou
On Fri, 23 Aug 1996 frasera1@westatpo.westat.com wrote:
> ----------------------------Original message----------------------------
> I work in a studio with a gorgious gas reduction kiln, firing to
> cone 9 or 10. The only problem is that often (painfully often) my
> pots are sticking to the kiln shelves. No, I don't have a
> dripping glaze problem, it just that the naked bottom of my pots
> are sticking. I've lost lots of chunk of carefully carved feet
> this way.
>
> In the studio we use a "wax resist for porcelain". Its basically
> normal wax resist with some chemical (was it alumina silica?)
> Should I be using some other type of wax resist, or is there some
> other trick here?
>
> Alexa
>
Sam Cuttell on sun 25 aug 96
At 12:55 PM 8/24/96 EDT, you wrote:
>----------------------------Original message----------------------------
>To avoid porcelain from sticking to itself (e.g. lids to jar seats) and to
>kiln shelves I put alumina oxide in my wax resist. I also dust the kiln
>shelves with alumina oxide or 200 mesh silica. This sticking problem never
>happens in oxidation at Cone 10 only in reduction. Anyone know why????
>
I have to agree with your last statement. I fire ^10 ox stoneware....and my
larger pieces (ie. the ones that shrink most) definately have sticking
problems. As I don't trim feet (flat trim) sometimes my edges have "knicks"
out of them.
My solution is to use flat pads (thrown) of bisque clay under my more
precious pieces. This way the pad shrinks at the exact same rate as the piece.
sam - alias the cat lady
Home of Manx cats, Cavalier King Charles Spaniels and the odd horse
Melbourne, Ontario, CANADA
(SW Ontario)
Sam Cuttell on mon 26 aug 96
At 07:05 PM 8/25/96 EDT, you wrote:
>----------------------------Original message----------------------------
>At 12:55 PM 8/24/96 EDT, you wrote:
>>----------------------------Original message----------------------------
>>To avoid porcelain from sticking to itself (e.g. lids to jar seats) and to
>>kiln shelves I put alumina oxide in my wax resist. I also dust the kiln
>>shelves with alumina oxide or 200 mesh silica. This sticking problem never
>>happens in oxidation at Cone 10 only in reduction. Anyone know why????
>>
>I have to agree with your last statement. I fire ^10 ox stoneware....and my
>larger pieces (ie. the ones that shrink most) definately have sticking
>problems. As I don't trim feet (flat trim) sometimes my edges have "knicks"
>out of them.
>
AAAARRRRGGGHHHHHHH........I meant DISagree
slip of the fingers - sorry.
sam - alias the cat lady
Home of Manx cats, Cavalier King Charles Spaniels and the odd horse
Melbourne, Ontario, CANADA
(SW Ontario)
Christine Fennimore on mon 26 aug 96
> I work in a studio with a gorgious gas reduction kiln, firing to
> cone 9 or 10. The only problem is that often (painfully often) my
> pots are sticking to the kiln shelves.
We have solved this same by mixing equal amounts of flour and alumina with
water to a runny paste consistency. This is then brushed onto a board
sitting right next to the kiln. As pots are put into the kiln, they are
first set down on the board and then loaded into the kiln. This has
completely eliminated the problem of porcelain sticking to the kiln shelves.
You want to be very careful with this stuff though and only get it on the
bottom of the pot! It takes just a liitle bit and works really well.
Ron Roy on mon 26 aug 96
The material of choise for preventing sticking is alumina. I use a high
alumina shelf wash - 10% ball and 90% alumina hydrate which I spray on. I
have two containers of wax, one without alumina for regular waxing and then
I put a line of the wax with alumina on the botton of the foot. If you get
alumina under glaze it interfers with the glaze sticking to the pot. I also
use some fine but granular alumina in wax to prevent my cone 10 terra sig
from sticking to shelves. A friend dips her finger in wax and alumina and
runs it around feet just before she stacks.
Ron Roy
Toronto, Canada
Evenings, call 416 439 2621
Fax, 416 438 7849
Richard Boyd on mon 26 aug 96
>----------------------------Original message----------------------------
>At 07:05 PM 8/25/96 EDT, you wrote:
>>----------------------------Original message----------------------------
>>At 12:55 PM 8/24/96 EDT, you wrote:
>>>----------------------------Original message----------------------------
What has always worked fine for me was to sprinkle a little silica sand
(sometimes called flint) onto the shelf. Doesn't take much, 3 or 4 pinches
at best.
Boyd
Iron River
boydr@up.net
ARoth25182 on thu 29 aug 96
I too fire to cone 10 and have had this problem.
My solution is to sprinkle some Alumina on a board and set each pot on the
board before stacking the piece into the kiln. I press the piece onto the
board and turn it a little. I use wax on the feet and the Alumina will
stick to the wax.
This works well and allows me to avoid having too much alumina loose in
the kiln.
It's a bummer when alumina falls into or onto a piece.
Good Luck
Andy Roth
Saratoga Pottery
Ballston Spa, NY
Bob Hanlin on mon 2 sep 96
>----------------------------Original message----------------------------
>I too fire to cone 10 and have had this problem.
>My solution is to sprinkle some Alumina on a board and set each pot on the
>board before stacking the piece into the kiln. I press the piece onto the
>board and turn it a little. I use wax on the feet and the Alumina will
>stick to the wax.
>This works well and allows me to avoid having too much alumina loose in
>the kiln.
>It's a bummer when alumina falls into or onto a piece.
>
>Good Luck
>
>Andy Roth
>Saratoga Pottery
>Ballston Spa, NY
Andy:
Try putting the aluminia hydrate into the wax you wax the bottoms of your
pots with. It settles to the bottom of the container but if you're applying
it with a brush you can reach down with each brushload and stir a bit of
aluminia. THe wax goes on about the same and looks the same but when it's
dry you can feel a bit of texture in it. When the pieces are fired, the
alumina hydrate keeps the piece from sticking (plucking). It also works as
a great way to keep lids from sticking to the pots.
BobH in OKC
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