Uneducated but enthusiastic ceramicist looking for advice about stoneware glazes

[Bauhaus]

@Callie Beller Diesel thanks for that long response and your research into the clay I used. I wouldn’t have known it’s possibly not suitable for functional ware at the temperature I am firing to. It certainly is a steep learning curve. I just bought 2 more bags of the stuff, because the kiln was only half full. Looks like I’ll have to try some ornaments, tiles, and maybe musical instruments instead of the plates and mugs I was designing and dreaming of. This is more interesting perhaps. 

@Babsthanks too, what do you mean heating prior to glazing? Stick it in the oven for a few minutes? I had half a kiln, it was my first firing on my own outside of any educational establishment. One bag of clay, many experimental pieces. I generally only learn through doing, it’s expensive but I won’t make the same mistake again. It’s less expensive than doing more college courses which seem to mainly teach the easy stuff about construction and concept.

[kswan]

I consider myself an artist first before being a potter. I got into clay much later than I did other art classes. You'll like the underglaze painting, I think.  As Neil said, the colors don't always come out as you might expect, so do some tests to begin with. The glaze on top can change the underglaze color too. I make tiny tiles that I coat with underglaze, then apply half with my satin glaze and half with my clear to see how they look. I use a glue dot to stick it onto the top of my underglaze jar so I have it as easy reference when I'm painting. 

If you make tiles to hang on the wall, you can make a 45 degree angled slot in the back that doesn't go all the way through. Then you can use that slot to hang it on a hook or a nail. 

You don't have to use all that clay up to make things, either. You can use it to make slump or hump molds and trimming chucks and things like that. Be sure to use a permanent marker on the clay bag to identify it when you purchase more than one type. It's easy to mix them up otherwise. 

[Callie Beller Diesel]

6 hours ago, Bauhaus said:

It’s less expensive than doing more college courses

Maybe, maybe not. Not all classes are made the same.

 The way you make pottery for a living is different than making a few things where your heart takes you. A lot of people are drawn to work with clay, because it’s tactile and fun, but not everyone wants or needs to be a professional production potter or a sculptor. Classes designed with hobbyists/other skilled non-professionals in mind have to omit a lot of information, because you’d loose too many students to frustration otherwise. If you know you want to make a living at it, taking a more process/skill building oriented class that might have less physical product to show at the end could save a lot of time and effort. 

[Babs]

On 6/14/2022 at 7:16 PM, Bauhaus said:

@Callie Beller Diesel thanks for that long response and your research into the clay I used. I wouldn’t have known it’s possibly not suitable for functional ware at the temperature I am firing to. It certainly is a steep learning curve. I just bought 2 more bags of the stuff, because the kiln was only half full. Looks like I’ll have to try some ornaments, tiles, and maybe musical instruments instead of the plates and mugs I was designing and dreaming of. This is more interesting perhaps. 

@Babsthanks too, what do you mean heating prior to glazing? Stick it in the oven for a few minutes? I had half a kiln, it was my first firing on my own outside of any educational establishment. One bag of clay, many experimental pieces. I generally only learn through doing, it’s expensive but I won’t make the same mistake again. It’s less expensive than doing more college courses which seem to mainly teach the easy stuff about construction and concept.

Most clays Gave the bisque and firing range on the bag swhere.

Research glaze firing schedules.

Because the pots require a certain porosity for the uptake of the undeglaze and glaze  folk have found heating pots up help this.....but most would not waste time or money.  

Your glazes would need to contain less water.

This has been discussed on these forums.

Imo do one pot, in the meantime,  make more pots,  a lot of folk underglaze at leatherhard stage prior to bisquing. Less chance of smearing, esp if brushing glaze app.

[Bc studio]

Hi, I’m enjoying this thread as there are so many great suggestions! Thanks so far… I have a question to add to the topic…. If I fire to 04 for bisque and to cone 5 or 6 for glaze, does this make the clay ‘stoneware’? Or for it to be ‘stoneware’ you have to bisque it to 5 or 6 first?  I’m making functional ceramics from kgm body. Thanks 

[Min]

1 hour ago, Bc studio said:

Hi, I’m enjoying this thread as there are so many great suggestions! Thanks so far… I have a question to add to the topic…. If I fire to 04 for bisque and to cone 5 or 6 for glaze, does this make the clay ‘stoneware’? Or for it to be ‘stoneware’ you have to bisque it to 5 or 6 first?  I’m making functional ceramics from kgm body. Thanks 

In the UK it's common to find claybodies with a wide firing range like the KGM clay does. When I looked it up the manufacturer states it can be fired at earthenware temps right up to 1280C which is approx cone 10. Problem with this is a clay can't be mature at both low and high ranges. Given that you are making pots for functional use I would suggest you find a clay that matures (has a top firing range) at cone 6 if that is your desired firing range.

For stoneware bisque firing it is recommended to bisque to a low cone, such as 04, then glaze fire to the cone the clay matures at. For KGM clay it will be the strongest and least have the least water absorption when fired to 1280C (approx cone 10)

Edited August 11, 2022 by Min
grammar

[Bc studio]

1 hour ago, Min said:

In the UK it's common to find claybodies with a wide firing range like the KGM clay does. When I looked it up the manufacturer states it can be fired at earthenware temps right up to 1280C which is approx cone 10. Problem with this is a clay can't be mature at both low and high ranges. Given that you are making pots for functional use I would suggest you find a clay that matures (has a top firing range) at cone 6 if that is your desired firing range.

For stoneware bisque firing it is recommended to bisque to a low cone, such as 04, then glaze fire to the cone the clay matures at. For KGM clay it will be the strongest and least have the least water absorption when fired to 1280C (approx cone 10)

Thanks so much min - all understood ! 

[Chilly]

On 6/13/2022 at 12:34 PM, Bauhaus said:

then paint transparent glaze

try to think this sentence as :  "then glaze with the transparent glaze"

The brush action is different to painting.  Glazing needs a loaded brush and allow the glaze to flow off the end of the brush in one sweep, then turn the brush over, and apply the next sweep to the next part of the pot.  Never scrub the glaze onto your pots like you might do with paint.  Painting and glazing are different actions, and need the different words stuck in your mind so you remember that.

So, to recap all the above comments:

bisque firing is to change clay (that can be re-wetted and turned back into workable stuff) into clay that is hard, but still porous.  Usually to cone 06-04

glaze-firing should turn the bisqued pot into a stronger, (vitirified ?) non-porous pot that will hold water.  Earthenware temperatures need fully glazing, stoneware temps can/should have bare bottoms and don't need to be fully glazed to be non-porous.  Can be cone 04 through to 6, 8, 12 or higher.

 

Any more questions - keep asking.