Kanorin's chunks of fired mud

[JeffS73]

There isn't too much chemical interaction between clay and glaze. Maybe it's more about application or firing temperature? A hotter firing this time would produce more running of the glaze, and give more time for crystals to grow during the cooling phase of the firing

I'm working my way through the Ceramic Materials Workshop online lectures about glaze chemistry and the lecturer keeps harping on it how they're relatively separate things Apparently the biggest difference is a different color behind the glaze, which is relatively transparent

Cool that you're doing CMW glaze class! I would disagree about clay glaze interaction, but it does seem to be down to the glaze chemistry. Any glaze that relies on iron for its characteristics can vary hugely on different clay bodies. For example, ddm, a floating blue will vary a lot depending on iron in the clay, but a Celadon or Jun won't, however they are very sensitive to titanium in the clay.

 

[Wood]

Cool that you're doing CMW glaze class! I would disagree about clay glaze interaction, but it does seem to be down to the glaze chemistry. Any glaze that relies on iron for its characteristics can vary hugely on different clay bodies. For example, ddm, a floating blue will vary a lot depending on iron in the clay, but a Celadon or Jun won't, however they are very sensitive to titanium in the clay.

Yes, but aren't those usually the exceptions to the trend of how glazes perform? That's the specific combination of floating blue + iron, and celadon/jun+porcelain/porcelaineous stoneware. My understanding is that for even these glazes, the chemical reaction is usually limited to the surface between the glaze and you're seeing that reaction through otherwise unchanged glass/glaze

Also, purely speculating based on this one photo, it's not the characteristic muddy red-brown of a high-iron clay, and definitely not a floating blue glaze. My guess would be a strontium-based matte, because those typically have rather muted colors. I easily could be way off because I'm just getting started learning glaze chemistry

Does this pattern match any chemical interactions you know of?

 

[Kanorin]

Also, purely speculating based on this one photo, it's not the characteristic muddy red-brown of a high-iron clay, and definitely not a floating blue glaze. My guess would be a strontium-based matte, because those typically have rather muted colors. I easily could be way off because I'm just getting started learning glaze chemistry

I don't think this is a high iron clay. I'll try to ask what's in the glaze the next time I'm over there.

 

[HorseloverFat]

There isn't too much chemical interaction between clay and glaze.

Correct!... HowEVER....

This is only correct, assuming Kanorin is bisque-firing before glazing...

I can assure you, when raw glazing, there is DEFINITE interactions between the clay and glaze at prime layers.



Which if you THINK about it... Is kind of a "duh" thing... When referring to bisque-then-glaze having no mingling....

Of course the clay doesn't demonstrate reactions .. it ALREADY (mostly) reacted in between 900-1100dF.....



Can't expect the lotion to work after you've been burnt...


I've heard...

I don't use sunscreen.

 

[HorseloverFat]

Looking good, by the way, Kanorin.

I have a bunch of "accidental black" mirror glazes..

It's fun to diagnose!

I remember::

One is an abundance of Cobalt.

One an unexpected reaction from some manganese clay body WITHIN the glaze and the strange-sourced Fe I was using.

One was too much boron.. not enough stabilizing flux...

One was inaccurately balanced ash which over-fluxed the mixture...

Ect...ect..

...

But "looking good!" Is definitely the main take-away.

 

[Wood]

Correct!... HowEVER....

This is only correct, assuming Kanorin is bisque-firing before glazing...

I can assure you, when raw glazing, there is DEFINITE interactions between the clay and glaze at prime layers.



Which if you THINK about it... Is kind of a "duh" thing... When referring to bisque-then-glaze having no mingling....

Of course the clay doesn't demonstrate reactions .. it ALREADY (mostly) reacted in between 900-1100dF.....



Can't expect the lotion to work after you've been burnt...


I've heard...

I don't use sunscreen.

Glaze ingredients don’t melt until the last 100 C of the firing, and only really sinter together before that point. The CMW lectures had a series of photos from an electron microscope inside a kiln during a firing and showed the same individual kaolinite throughout it. Super cool

Not sure about how much raw glazing would really change the interaction of clay and glaze either. All water, chemically bound or otherwise, would be driven off way before either glaze or clay begins to melt or vitrify

 

[JeffS73]

Glaze ingredients don’t melt until the last 100 C of the firing, and only really sinter together before that point. The CMW lectures had a series of photos from an electron microscope inside a kiln during a firing and showed the same individual kaolinite throughout it. Super cool

Not sure about how much raw glazing would really change the interaction of clay and glaze either. All water, chemically bound or otherwise, would be driven off way before either glaze or clay begins to melt or vitrify

I like this table in the potters dictionary and find it useful when thinking about the chemistry:


I respect the CMW course, and hope to take it. I know Matt fires mostly on porcelain and there is less interaction there.

I fire mostly on iron containing clays and whilst I still class myself as a noob, more than half of my 1000 or so glaze test tiles interact with the clay body, even if its just where they break and introduce iron at the edge. I have a commercial grey clay that gets its colour from a small amount of Chrome - this changes almost every glaze I put on it. Same for a black clay with Manganese. All I'm saying is it's wonderful multi-dimensional brain melter

 

[BrightsideB]

I like this table in the potters dictionary and find it useful when thinking about the chemistry:
View attachment 507600

I respect the CMW course, and hope to take it. I know Matt fires mostly on porcelain and there is less interaction there.

I fire mostly on iron containing clays and whilst I still class myself as a noob, more than half of my 1000 or so glaze test tiles interact with the clay body, even if its just where they break and introduce iron at the edge. I have a commercial grey clay that gets its colour from a small amount of Chrome - this changes almost every glaze I put on it. Same for a black clay with Manganese. All I'm saying is it's wonderful multi-dimensional brain melter

Have you experimented with applying engobes and glazing over them? That’s something I am going to start experimenting with.

The speckled clay with manganese will run with certain glazes. You’re right makeup of a clay can be a total game changer with glazes.

 

[HorseloverFat]

Glaze ingredients don’t melt until the last 100 C of the firing, and only really sinter together before that point. The CMW lectures had a series of photos from an electron microscope inside a kiln during a firing and showed the same individual kaolinite throughout it. Super cool

Not sure about how much raw glazing would really change the interaction of clay and glaze either. All water, chemically bound or otherwise, would be driven off way before either glaze or clay begins to melt or vitrify

Well...

Just look into HOW one can achieve oxidation colors, in a reduction environment....

It has to do with the interaction certain "fireclays" and porcelain bodies and the oxides in the glaze solution.

I am not arguing, or parroting things I've heard.. I am letting you know something I experienced and learned through DOING it.

 

[HorseloverFat]

Glaze ingredients don’t melt until the last 100 C of the firing, and only really sinter together before that point. The CMW lectures had a series of photos from an electron microscope inside a kiln during a firing and showed the same individual kaolinite throughout it. Super cool!

This does sound AWESOME! I'm super jealous that you got to be a part of that!!


But that "last 100 C" of firing"-rule... AGAIN... this is ASSUMING a particular "heat/cone"... and ASSUMING a particular firing schedule vs. Range of fully-fired body.

We must remember that low and mid-fire exist. While not forgetting that most clay bodies, themselves have "ranges"... with their vitreous point set "betwixt" those parameters.

When one is mixing their own glazes... sans recipes (besides your own notes)... it's ALL.. kind of "relative" to the scenario. Will vary upon heat goals, aesthetic goals, functional goals ect.

It's useful to point out, here.... MANY of the glossy glazes that I BUILD, that get fired to cones 6-8... are built upon a clear cone 04-05 glaze. One just needs to know how to balance the construct of the glaze. (The reason I point this out, is because this would mean that these glazes, even stabilized with shamanic alchemy () melt down much sooner than standard Cone6-8 glazes.)

My kiln fires to a different cone on each shelf.. I TRY to stack accordingly.. but sometimes a clay body geared for 5/6... ends up in a 7... so this, one more time, would skew "rules" and standards.

I hope this is not coming off aggressive, (the things you are saying ARE correct in the capacities you are speaking of) I am just REALLY liking this conversation!

Salt/other vapor glazing, Raku (hotspot), and dung-pile glazing are few more "fringe thoughts" that challenge "guidelines".

 

[Kanorin]

To answer a question: yes I have been bisque firing and then glazing and then reduction firing in a gas kiln to cone 10.

These turned out pretty cool.

 

[HorseloverFat]

To answer a question: yes I have been bisque firing and then glazing and then reduction firing in a gas kiln to cone 10.

These turned out pretty cool.
View attachment 508950View attachment 508951

Nice!

I remember fabricating/firing pieces that looked like glazed, ginger cookies too!



...


I did not realize you used gas reduction!

What does your set-up look like?

 

[Kanorin]

Biggest tray yet. A little bit of warping, but not too bad. It’s about 14 x 8 or so

 

[HorseloverFat]

Looking nice! That kind of warp is just something you slowly learn to "curb" through technique.

I've found, that with thinner walls like that, more time to harden AFTER cutting but before assembling REALLY helps.

Pieces that thin, should be fairly stiff and unbending BEFORE assembly. And be careful of the DIRECTIONS you end up "stressing" the walls during fabrication.

 

[Kanorin]

This pot I’ll be donating for one of the kusamono workshops with Young Choe at Bonsai Central next May.

 

[thatdirtykid]

This does sound AWESOME! I'm super jealous that you got to be a part of that!!




Salt/other vapor glazing, Raku (hotspot), and dung-pile glazing are few more "fringe thoughts" that challenge "guidelines".

Love raku, but I do not believe a raku pot would last even a single season holding water. I am not sure if there are processes that would make that more feasible for a functional vessel. Maybe treating the raku as a luster firing on an already higher fired pot? I don't think you would get the rich blacks that I love in raku with an almost vitrified clay body though. Maybe I should reach out to my old professor who apprenticed in a raku studio for a few years...

IMO Salt firing is criminally underused in ceramics, soda and wood just being more popular. Some of my best pieces were salt fired shino glazes, sometimes fired 3 or 4 times. If I had my own studio a salt kiln probably wouldn't be top priority though. Salt firing is pretty dam hard on brick and furniture.

 

[BrightsideB]

Love raku, but I do not believe a raku pot would last even a single season holding water. I am not sure if there are processes that would make that more feasible for a functional vessel. Maybe treating the raku as a luster firing on an already higher fired pot? I don't think you would get the rich blacks that I love in raku with an almost vitrified clay body though. Maybe I should reach out to my old professor who apprenticed in a raku studio for a few years...

IMO Salt firing is criminally underused in ceramics, soda and wood just being more popular. Some of my best pieces were salt fired shino glazes, sometimes fired 3 or 4 times. If I had my own studio a salt kiln probably wouldn't be top priority though. Salt firing is pretty dam hard on brick and furniture.

Why not use Raku fired pottery for a tropical or a tree that has to remain above freezing? I like the vibrant colors of raku. I can see them looking interesting with a tropical.

 

[thatdirtykid]

I am not sure. Raku is generally quite a bit more porous than even terracotta. IIRC it's generally fired to around ^06 and feels almost soft. I just remember being taught that it's only good as 100% decorative. I genuinely would wonder if they wouldn't eventually dissolve just from moisture. They do tend to weather and age rather quickly in the elements.
I don't believe I have any vessels I could experiment with, I mostly made wall pieces/decorative stuff in my brief experimentation with Raku. Raku/Pit/Horsehair/dung sure has an impressive range of surfaces you can achieve. I am curious as well.

 

[Kanorin]

Neat little shohin/accent that I added some texture too with slip.

Around 14” landscape tray

 

[Kanorin]

And here’s my least-warped landscape tray yet. Around 15” I think.