The clay here is called jiani, it’s found in various layers along with other yixing clay (but not used for teapots). The translation of this video screen capture (below), provides a fascinating insight into how they judge the suitable temperature at which to fire. First, technicians measure the porosity and firing shrinkage over a range of temperatures, likely looking for a firing "sweet spot". Notice shrinkage reaches a maximum at 1100C, then drops off as the clay begins to expand. But this is not the only thing considered. Notice, in the comments, that they are also looking for "surface luster" (which is not found). They also comment about a "dull sound" and "crisp/clear sound" (so they must create a sounding vessel of some sort). They also break a fired piece and comment of the nature of the cross section, revealing something else interesting: The clay holds on to a dense cross section for 100C degrees after reaching maximum fired shrinkage.

The Yixing teapot craftsmen appear to break all the rules and yet produce impossibly delicate and symmetrical pieces. Hao-Tong Yan, one of those craftsmen, and I have been trying to understand the technical reasons for how this amazing craft is possible. It turns out not to be magic, but actually a highly evolved understanding of a very unusual material. Here are some of the things that we are coming to understand (which is making it possible to create a facsimile of the clay in North America).

-The clay is not highly plastic; the workability comes from surprising places.
-The clay has impossibly low water content, yet can be formed.
-Craftsmen flatten the clay with a mallet, instead of rolling it, yet it does not stick to the board.
-Sections are simply glued with slip, yet they hold.
-The clay burnishes, yet is not smooth.
-Fired ware is smooth, yet the soft clay appears sandy.
-The fired surface is glossy, yet there is no glaze.
-The fired clay appears super dense yet does have porosity.
-The Yixing ore can have the appearance of being like rocks, yet they make a workable clay body from it.

Hundreds of bouquets of flowers will have a significant environmental impact. I sent one and if you already sent one, I will credit your Insight-live account for 4 years, just let me know. I have other things in mind, will let you know.

Wow. And to Dominic Legault, who set this up and stopped it. It is not the money; it is knowing that my work has been worth something to you. My friends and neighbors don't know what I do for a living. Now they do!

Maybe I should get a car! Just joking! I'll use it to better ensure the survival of Digitalfire. Laying the groundwork for that is primarily a technical challenge for me and people I can bring on board virtually. Here is the plan:

I need goodwill with Plainsman. I know you are passionate about this whole affair in the past few days. I underestimated how much. Some were so passionate they have caused trauma with Plainsman staff, we must undo that. Having goodwill with the company I partnered with to make Digitalfire is so important and will make me so happy. We both "pulled the dragon's tail" over misunderstandings. Here is the biggest one: Digital Fire is not at risk and never was from Plainsman. I need goodwill, especially if you put staff under stress, and you can help me get it. My first idea was to fill their office with hundreds of bouquets of flowers, but now I realize that's too much enfironmental impact. I'll credit you 4 years of Insight-live if you already did.

Please, everyone stop bashing Plainsman. I never intended that. Thier staff is suffering under attack. They are really upset. So much of this is misunderstandings. We both pulled the tail of a dragon.

The message that I put up that Digitalfire would shut down on June 26 because I was unable to meet the demands in the lawyer’s ultimatum is what made me fearful and started the whole thing. I was deluged with messages I couldn’t hope to answer so I created a response and pasted it in. I texted that response to Plainsman as well so they knew what I was saying. I should have stated more strongly that this is not about bashing Plainsman. I am very sorry for that. They are better positioned than any other company in North America because they have their own clay deposits, I want to work with them not against them.

The old logo is from the late 1980s and was used to promote Desktop Insight at trade shows and to advertise it in magazines and later on the early internet. It was done in Aldus Freehand, an early competitor to Adobe Illustrator. Vector graphic illustration was revolutionary at the time. Amazingly, many artists even today do not know what vector graphics is, they are still working with "pixel pusher" apps like Photoshop.

I asked Gemini how it made this, and it said: "I started with a blank canvas of random digital noise (a chaotic grid of pixels) and gradually refined that noise over multiple steps based on your prompt and the layout of your original image. There was not need for a vector stage; the smooth transitions, glowing embers, and soft gradients are baked right into the generation process from the very beginning."

Glazing black clay bodies stained with manganese is just about impossible with typical transparent glazes. The glaze over-fluxes the clay surface and ruins the color. Worse, if it accelerates surface maturity, the body can blister or generate LOI gases that blister the glaze. How about transparent glazes over a black engobe instead? At least the body color is not lost. But the wrong transparent glaze can do what you see here (inside left).

These mugs are a buff stoneware, Plainsman M340. A black engobe was applied by pouring the inside and dipping the outside two-thirds of the way down.

Left: A L3954F black engobe was applied inside and upper exterior at leather hard. After firing to cone 6 using the PLC6DS schedule, G2926B—which is crystal clear on M340 itself—became completely clouded over the engobe because bubbles generated during firing remained trapped in the melt.

Right: The entire mug was dipped in GA6-B. The Alberta Slip particles and the melt characteristics of GA6-B promote bubble coalescence and escape, producing an exceptionally glossy jet-black surface over the same engobe.

When you learn to make and use engobes correctly, they make magic possible. Here I am turning a dark rustic body into a smooth white one (rear mugs) and a white body into a dark one (front). The engobes have been applied at the leather-hard stage. That is the perfect time, the engobe and body are clay bodies, designed to fit each other; they dry together and fire together creating an inseparable bond.

Handles have been applied, and they have dried to stiff leather hard. Engobe was poured in, poured out, then the mugs were pressed, lip down, into it and extracted. No dwell time was needed. This dipping engobe is DIY thixotropic (not available commercially anywhere). That means I tuned it just before use, to just the right degree of gel (enough for it to drain to the right thickness, then gel just as the last few drops fall from the rim). Honestly, these are a beauty to behold at this stage, the silky, drip-free surface is just so perfect.

I wish to express my gratitude to all the people and organizations around the world that have been republishing content on Digitalfire (most often with translation). They are mostly people who love ceramics and IT like me; on every continent. When people ask, I almost always agree; when they don’t it is still ok. To make things clearer I will put content under a licence to control use: Likely CC BY and ODC-BY. I feel gratitude that the pages are valued (so please don't hassle them for copyright infringement). Thank-you messages, often emotional, have arrived almost every day for many years. They come from individuals, but also large corporations, schools, organizations and even high-tech industries. Some work in the background, the mainstream or management unaware of their brilliance. I've gotten thousands of cups of virtual coffee and countless donations in the past few years. It is a little overwhelming! Some very exciting liaisons are forming with republishers; you will see them as outgoing links and added functionality at digitalfire.com.