Tell Me Why This Is A Bad Idea 1

[Guest]

I want to glaze the bottom of a pot that has no foot and use a resist on the rim, then I want to fire it with the rim on the shelf and the bottom facing up.

Will I run into problems with the gases inside the pot not being able to escape?

[Marcia Selsor]

The only thing I can think of would be a rough texture to the lips. gases escape through the surface although you may capture some with the inverted form. I was part of a large salt kiln firing in the 70s where 2 very large planters were stacked lip to lip. When they were taken apart after the firing, sulphur could be smelled.

Marcia

[oldlady]

if you have some 1/2 inch posts, why not rest the rim of the pot on 3 of the posts to allow air under the pot?

[Min]

Chances are the rim will deform and go out of round unless what it is sitting on can shrink at the same rate as the pot. Roll out some of the same clay as the pot is made from, it can be super thin. Cut out a pancake of clay just big enough to rest the rim on (can cut the center of the pancake out to save clay). Dry the pancake between batts or boards or whatever so it stays flat. Bisque it then place your upside pot on it when glaze firing. The pot and pancake will shrink at the same rate so the rim will stay true. If you are using porcelain slap a quick coat of kiln wash on the pancake. 

 

I wouldn't worry about off gassing, casseroles, french butter dishes, boxes, lidded jars etc are all fired as a closed unit.

[neilestrick]

Do what Min says. It will definitely warp otherwise.

[Guest]

Thanks all

[Guest]

Chances are the rim will deform and go out of round unless what it is sitting on can shrink at the same rate as the pot. Roll out some of the same clay as the pot is made from, it can be super thin. Cut out a pancake of clay just big enough to rest the rim on (can cut the center of the pancake out to save clay). Dry the pancake between batts or boards or whatever so it stays flat. Bisque it then place your upside pot on it when glaze firing. The pot and pancake will shrink at the same rate so the rim will stay true. If you are using porcelain slap a quick coat of kiln wash on the pancake. 

 

I wouldn't worry about off gassing, casseroles, french butter dishes, boxes, lidded jars etc are all fired as a closed unit.

 

I've been thinking about this

I'll be using stoneware, but won't the pot stick to the pancake when glaze firing?

[Min]

 

Chances are the rim will deform and go out of round unless what it is sitting on can shrink at the same rate as the pot. Roll out some of the same clay as the pot is made from, it can be super thin. Cut out a pancake of clay just big enough to rest the rim on (can cut the center of the pancake out to save clay). Dry the pancake between batts or boards or whatever so it stays flat. Bisque it then place your upside pot on it when glaze firing. The pot and pancake will shrink at the same rate so the rim will stay true. If you are using porcelain slap a quick coat of kiln wash on the pancake. 

 

I wouldn't worry about off gassing, casseroles, french butter dishes, boxes, lidded jars etc are all fired as a closed unit.

 

I've been thinking about this

I'll be using stoneware, but won't the pot stick to the pancake when glaze firing?

 

 

Sorry, I just assumed you are not glazing the rim. If you want to glaze it all over then you would have to use stilts on the bottom and grind off the little sharp bits of glaze afterwards, firing it right side up. Stilts work best for small light pieces when firing higher than earthenware temps.

[Guest]

You are right, I'm not glazing the rim. There are a lot of holes in what I know about ceramics, this seems to be one of them, sorry.

 

I had assumed that if unglazed stoneware was touching unglazed stoneware it would fuse together during a glaze firing. Looks like I was wrong, its the glaze that sticks together.

 

Got it, Thanks!

[S. Dean]

 

Chances are the rim will deform and go out of round unless what it is sitting on can shrink at the same rate as the pot. Roll out some of the same clay as the pot is made from, it can be super thin. Cut out a pancake of clay just big enough to rest the rim on (can cut the center of the pancake out to save clay). Dry the pancake between batts or boards or whatever so it stays flat. Bisque it then place your upside pot on it when glaze firing. The pot and pancake will shrink at the same rate so the rim will stay true. If you are using porcelain slap a quick coat of kiln wash on the pancake. 

 

I wouldn't worry about off gassing, casseroles, french butter dishes, boxes, lidded jars etc are all fired as a closed unit.

 

I've been thinking about this

I'll be using stoneware, but won't the pot stick to the pancake when glaze firing?

 

 

 

RonSa,

 

Assuming that by putting wax resist on the rim you are doing so to create an unglazed surface, this unglazed rim should not stick to the unglazed pancake.  As Min pointed out earlier, this is quite similar to firing an unglazed portion of a lid on an unglazed gallery of the pot (a common practice).  You should have no sticking issues with stoneware.  However, this may not work with porcelain since a lot of porcelains will flux a bit at maturity.  This can result in "plucking" - i.e., when the porcelain becomes so pyroplastic that unglazed portions can fuse to whatever it is touching.  In that case, adding some alumina in the wax resist is useful - just make sure you don't use this wax with alumina for any resist over glaze

 

-SD

[Guest]

Thanks SD

[lbbloom]

I have been doing this with great success over the past 6 months for about 12 large wide shallow bowls and 6 medium deep bowls.  I haven't used a cookie.  I use stoneware fired to cone 10 in a gas kiln.  no glaze drips, no rim deformities.  

[oldlady]

would love to see a photo of the pot in question, RonSa.   what is it for?

[Guest]

Oldlady, I'll take a picture of it next time I'm at in the studio. Its still leather hard

What its for? Art's sake.

 

 

I have been doing this with great success over the past 6 months for about 12 large wide shallow bowls and 6 medium deep bowls.  I haven't used a cookie.  I use stoneware fired to cone 10 in a gas kiln.  no glaze drips, no rim deformities.  

 

You just place it on the shelf? Hmmm, I like easy

[Magnolia Mud Research]

Ron,
 
I occasionally fire cups upside down at cone 10 (reduction) and always place them on either wads of wadding, or on sea shells if the rims are glazed.  Many of our glazes have rather high LOI and I want the in-cup atmosphere to be relatively consistent with the kiln atmosphere; therefore, wads/shells are required.  The idea is from an old wood firer who did not want stray wood ash inside his cups and bowls. 
 

If the rims are glazed, and on shells, there will be marks where the shells touched the rim and the marks may need polishing after the firing. 
 
Firing upside down can provide interesting glaze-on-glaze decorative opportunities such as making a cup with glaze that runs 'uphill'.  It also allows for decorative work on the bottom of the cup.
 
LT

[oldlady]

i fire my birdhouses upside down on posts.  a single 6 inch post for a 5 inch birdhouse.  the post goes into the center because the birds do not care if the interior is glazed.  it works for planters but obviously not if it is for Art.  i hear he is very particular.

[Guest]

would love to see a photo of the pot in question, RonSa.   what is it for?

 

Yes Art is a finicky guy, either he is or he isn't.

 

Here is what I'm working on, they are meant to slightly rock when sitting on a table

[Callie Beller Diesel]

With something that small, you shouldn't have any issues firing it on the rim. All the problems everyone's been troubleshooting are issues on pieces with more mass, or wider rims than that, or made from porcelain. If you're worried about circulation in the kiln, fire them on some small wadding or clay coils, but I think even that might be overkill for those little sweeties.

[oldlady]

 ronsa, for the visual pleasure of it, look up joseph lonewolf pottery.  i am lucky enough to have a thin paperback book with his work in it.  he worked in the same size as your littlest one.  i think art would like them, too.

[Guest]

Thanks ladies,

 

These items for me are proof of concept in building and glazing. Once I'm happy with what I'm doing I'll be making larger ones. Although, I do like working small and may continue after seeing Joseph Lonewolf's pottery. I love his work.

 

(made from wood)