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Tony Hansen
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Chemistry plus physics. Maintain your recipes, test results, firing schedules, pictures, materials, projects, etc. Access your data from any connected device. Import desktop Insight data (and of other products). Group accounts for industry and education. Private accounts for potters. Get started.

Conquer the Glaze Dragon With Digitalfire Reference info and software

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Interactive glaze chemistry for the desktop. Free (no longer in development but still maintained, M1 Mac version now available). Download here or in the Files panel within your Insight-live.com account.


What people have said about Digitalfire

  • Your work has been incredibly helpful. Magic of Fire especially.
  • I have not been pottery long and I have decided to try to make my own glazes. Your web site is great. I like your cone 6 base glaze.
  • After perusing your site for some time, I am really getting the sense of what a valuable resource it is. Thank you for it.
  • Thank you for all the wonderful work you do for the ceramic community.
  • THANKS so much for all of the information you share at no cost. It really helps me. I feel a little guilty for not subscribing to Insight, but I am working toward that. You have truly changed the way I think about glaze, and I appreciate you. thanks. future subscriber/fledgling potter
  • Firstly, I want to thank you about this very good site in the net which helps very much in the development of the ceramics industry.
  • When my group of potters are pressed to improve our glazes they say if the old way is not broken yet why don't you buy yourself some kind of a kit to play with new glazes and then we can make it for everyone. You got to be kidding I say to myself. Anyway, your website will help me help the group out of some old and boring glazes if I can see forward enough. Thanks for all this important info, I can't believe this website is here!
  • I'm trying to access a great article on deflocculation. I have formulated so many casting slips over the years with the help of what I learned in that article and on this site.
  • Your materials database has been the best source of information for me for a long time. Even most of the European frits are in there and this is not true for many books.
  • I want to say THANK YOU! THANK YOU! for writing this book. It is exactly what I was looking for! I studied at a 4 year institutions--7 semesters in the ceramics department and I was taught how to calculate glazes with the empirical formula but that was it--no expansion stuff, etc. I wanted more than anything to have a knowledge base to create safe glazes, resolve problems like crazing, and the list goes on. In reviewing parts of your book many of my questions have already been answered. I absolutely love the way you address crazing--and yes, I did try many of the suggestions that were in that CM article and they didn't work. Now I know why. I have a lot to learn but am elated with what I have learned so far.

What people have said about Insight-Live

  • Thank you so much for this site and all the information. It's such a gift to have a reliable, authoritative source of information.
  • Thank you again for the amazing website and wealth of information!!! InsightLive is proving to be an incredible asset as well!!!
  • And I want to add - you are doing a magnificent job with your webpage. Just unbelievable amount of work and information you put there. I have learned a lot from your webpage. Thank you.
  • Thank you so much for visiting my site. It really means so much to me, being that the info and recipes on Digitalfire helped me SO much and greatly contributed to where I am today with my pottery. I am so grateful for all of the information you share!
  • Learning ceramics has been a long process full of tests, frustration but at the end full satisfaction once we learn more every day... Thank you for your website, I use it for constant reference
  • First off, I want to thank you for building Digitalfire. It is an incredibly valuable ceramic resource.
  • I am a long time admirer of your ceramics data base and teach at ... University.
  • I have to say as the subject says i am completely blown away by the amount of valuable information I have just taken in over around 4 hours or reading through your vast content and watching your videos on youtube! I am now a big fan and will for sure sign up with an insight live account as soon as I can!
  • I’ve told you before but it never hurts to say it again, this is great stuff and I get so much info from your posts. Extremely valuable! Thanks so very much for all you do.
  • Your website is such a valuable and dependable wealth of knowledge. I’ve had a break from ceramics for a couple of years and have loved that I’ve been able to return to the Insight Live database for my recipes and have read countless articles of yours on glazes. Thank you!

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Blog

A test mug I made back in 1981

It has a story that goes back to early Digitalfire

This is a cone 6 oxidation test mug I made in 1981. The speckling in the glaze was made by adding iron stone concretion particles. But this also has a story. Most potters at the time were firing cone 10R or low-temperature, cone 6 electric stoneware was a new development. Note the incised code number: "81-R-5". Digitalfire data archival was already well underway on my TRS-80 computers. The base also has a "60#" marking. I was trying a finer 60 mesh particle size to alleviate the glaze pinholing problems that plagued Plainsman customers at the time (their products were made at 42 mesh and kilns did not have controllers that enabled drop-and-hold or even hold-at-temperature firings that are used now). Pinholing was one of the first glaze problems that I studied; many glaze chemistry projects, using my new Desktop Insight, were aimed at making glazes having melts of lower surface tension and higher melt fluidity (using frits).

Context: Tony Hansen's Pottery Gallery.., Tony Hansen, Tony Hansen pottery what.., Hansen, Glaze Pinholes, Pitting

Friday 3rd July 2026

Technicians study the physics of Yixing clay

To determine the ideal firing temperature

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.

Temp Shrinkage Porosity Visual & Physical Characteristics
1000°C 8.3% 7.7% Orange-yellow, dense cross-section, relatively dull sound, matte surface (no luster).
1100°C 16.1% 4.2% Deep purplish-red, dense cross-section, crisp/clear sound, matte surface (no luster).
1150°C 14.8% 3.9% Purplish-red with a hint of brown, dense cross-section, crisp/clear sound, matte surface (no luster).
1200°C 14.7% 3.0% Brownish-red, dense cross-section, crisp/clear sound, matte surface (no luster).
1250°C 10.9% 2.6% Brownish-red, iron-rich melt-holes on the surface, dense, crisp/clear sound, produces bloating/bubbles.
1300°C 3.5% 3.4% Brownish-red, iron-rich melt-holes on the surface, severe deformation, has a relatively large amount of bloating/bubbles.

Context: This terra cotta clay.., How to decide what.., Yixing Teapots

Friday 26th June 2026

Yixing craftswomen at work

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.

Context: Yixing Teapots

Thursday 25th June 2026

GoFundMe Refund Initiated

Thanks again to Dominic Legault, who set this up and stopped it. This is my first exposure to a fundraiser; it is amazing what is possible. I was obviously excited about how it could accelerate my succession plan, but now realize that Digitalfire has to remain completely a volunteer labour of love. I was worried about Dominic's reaction to cancelling this, but he is on board.

The succession plan is unchanged, click to see more

It is a code-museum (because I started around 1982 using dBase II). That being said, about 5 years ago I converted Digitalfire to an API fronted database that endpoint code calls to create pages on the fly. This is coupled with a backend custom content management system that interacts directly with the database; thus, no pages are edited, only DB records. But a lot of old code is still there. Here are the current priorities:

  • The code is only partially on GitHub (required for team development and code analysis). I am refactoring it to adhere to PSR-4 coding standards (this is a rote process that I have been working on for about 6 months). As soon as I am ready, or before, I'll need help to write or improve the unit testing.
  • Document and publish the API to enable coders to create products that use the data from the API (e.g. machine translation). Explore refactoring in Python or JS/Typescript.
  • An MCP server, in Typescript or Python, to respond to queries from answer engines, thus supporting AEO.
  • Front the content management system in a secure way so that multiple people can start contributing and error checking. Convert to API access.

Other priorities that recent events indicate:

  • Implement a hashtagging system in the people database (for the newsletter) so that any who offer help can be classified and not forgotten.
  • Adopt Creative Commons licensing to enable students and teachers to quote and use without fear of copyright issues.
  • Document testimonials well to be able to demonstrate harm if the service is ever threatened.

As noted above, at the beginning of Covid, I redesigned Digitalfire as a client/server page generation system. An API, fronting the database, can run on one server while the page-generator can run on another server (by querying the API). There is a lot of caching. The content management system is custom-written for the information hierarchy; it runs on the same server as the API.

Please don’t believe twisted interpretations of the events during the latter part of June. You have seen me share freely for well over 4 decades. Please rely on my record rather than misinformed recent postings. I don’t rebut or flame people on social. But it does hurt when they say things that are totally against my character. As soon as I learned a GoFundMe had been started, I posted the succession plan. But it was behind a disclosure triangle and people were not opening it (see above). I have been working on item 1 for a year already; hopefully, 6 more months will do it. It shocks me how big and complex Digitalfire has become!

Saturday 20th June 2026

Resolution Achieved!

If you already sent, get 4 years Insight-live credit

I posted this on June 19.

I need goodwill with Plainsman. I know you have been passionate about this whole affair in the past few days. I underestimated how much. Some were so passionate that 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.

I consulted Plainsman before posting this, and they requested I add: 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 environmental impact. I'll credit you 4 years of Insight-live if you already did (this statement was added after I realized this was not a wise request).

Friday 19th June 2026

Please Stop!

On June 19 I posted this: Please, everyone, stop bashing Plainsman. I never intended that. Their 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, they are currently the only hope to have a Canadian ball clay and kaolin.

Friday 19th June 2026

Thank you sooo much!

Thank you to the hundreds of messages I am getting every day for support. Yikes. I can assure everyone I am not retiring; I am just getting started. I cannot believe the offers of help I am getting from coder/potters, lawyers, negotiators, designers, etc; there are so many of them. And how many countries. This is amazing. Messages from countries where potters and industry rely on Digitalfire because ceramic fabrication information is either kept highly secretive, despite a large manufacturing sector, or simply doesn't exist, really moved me. And an offer from a Google engineer to help. Or even a suggestion to move the dark web! Information on how to change licensing to clarify reuse. Advice from human rights experts on the importance of freedom of information. How to organize team coding. How to automate translation. Many offered physical server resources and hosting. Others offered new tools they have developed to integrate into Digitalfire. And so much more.

Wednesday 17th June 2026

1988 Insight logo reimagined by Gemini

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."

Context: Here is what digitalfire.., Digitalfire Insight

Saturday 13th June 2026

Same body, same outside glaze.

But the inside transparent glaze is different

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.

Monday 8th June 2026

Here is what dipping engobes can do:

Go on even. In one coat. Stay put.

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.

Context: L3954B, How stop dripping and.., Here s how I.., Why your supplier does.., Why your supplier does..

Monday 8th June 2026



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