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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

Download for Mac, PC, Linux

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

  • All your info on glaze chemistry and material characteristics are very informative and great catalysts for pushing me to take things a bit further. Most appreciated.
  • Hi, I love your work and I would like to participate.
  • Many Solution Regarding Ceramic Problems Got From Your Website.Thank You Very Much.
  • I have found your information extremely helpful - re firing and troubleshooting. Thank you!
  • I was really impressed with the way the ideas were presented and reinforced with analogies (especially those dealing with the importance of understanding glaze composition)
  • Go look at Tony Hansens page and look at Insite. Incredible amounts of information. He has a great explanation of .. Shivering ---and the opposite----- Crazing. Cause and solution.
  • I have been a ceramic consultant for many years and working in many parts of the world and must say that you are doing a very nice job with your website and software.
  • I have almost finished your book, THE MAGIC OF FIRE. I am enjoying it very much. I am sure that this is a book that I will reread many times.
  • Very useful articles on practical solutions to the every day problems Ceramic Technicians face in their organizations.
  • Thanks for your great contribution over the years to our field of work.

What people have said about Insight-Live

  • Love the post (about leaching in glazes). I am the bad guy on Facebook ceramic because I always bring up this subject. So sad.
  • As a side note: most of the students did access your information in their presentations. I found it interesting that your work is becoming foundational.
  • You have done more for the advancement of ceramic knowledge than anyone I can think of. Thanks again! The information you provide and the work you have done is invaluable. I can't tell you how many problems I have solved because of insight and the reference library! Thanks again for all of the help you have provided.
  • Thanks again for your website. It has helped me no end.
  • I teach ceramics and have been doing it a long time. I am also a subscriber to your site. You are a Godsend and a wealth of information, and I appreciate you sharing your knowledge with our community. So I've been doing this a long time, and ceramics never ceases to humble me.
  • I've said it before, but I can't say it enough, thank you for all your work on digitalfire and insight.
  • Just wanted to say thanks for such a great and useful product. Been learning via pen & paper, which I don't regret, but I should've signed up a lot sooner.
  • Thanks for sharing your extensive knowlege with the clay community.
  • I've really appreciated using your insight-live.com software.
  • 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
Please, everyone, don't panic and stop downloading to save all the pages, the ISP is warning me about overload. The internet archive has everything. Read your social media to find out what is going on. I am taking this down for a few hours to set up throttling. Please be patient. I’ll post at https://www.instagram.com/tonyatdigitalfire and https://www.facebook.com/tony.hansen.3990/

Digitalfire will shut down on June 26. I no longer have the authority to grant exemption to a section in the Terms and Conditions of using material in the Insight-Live account from which I built the source material. While there are ways to comply with the take-down order, they are beyond my means because of how complex and large the site has become in the past 35+ years. It has been a wild ride for a shy prairie boy, thanks to everyone for your support. Insight-live.com general operation is not affected by this.

Monthly Tech-Tip from Tony Hansen

I will send practical posts like these (from thousands I maintain). No ads or tracking. The first email will provide one-click unsubscribe. Signup is being email-bombed by bots. For now, please subscribe inside your insight-live.com account.


Blog

GoFundMe Campaign

Be careful

Please verify with your social connections that any donation invitation, e.g. GoFundMe, is genuine. If you know of a legitimate one not listed here, please let me know. My apologies if you made one and it is not here yet.

The first one is at https://www.gofundme.com/f/help-save-digitalfire. I am beyond grateful to Dominic Legault to initiate this.

Wednesday 17th 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, there are so many of them. And how many countries. This is amazing. One message from a country where information is kept highly secretive really moved me. And an offer from a Google engineer to help. Or even a suggestion to move the dark web!

I have never been really emotional, but this is pushing me. Plus, my wife and I spent the first night with a family whose son drowned in the local lake two days ago. It was the most horrible thing we have ever endured, even worse than this. I really needed all this side-channel support in the last two days of their sorrow, it helped so much.

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

No glaze chemistry needed

At least not right away

You have 147 glaze recipes. How can you get your head around all of them? Is glaze chemistry needed? No, that's a "maybe" way in the future. Right now, you need to start organized documentation. The recipe for each. A few pictures of each fired on different clay bodies, different thicknesses. Perhaps slow and fast-cooled firing. This is what an account at Insight-live does well. What it does even better is tracking your testing. The first step is to assign each recipe a proper code number (replacing these) and write that on all test specimens and buckets. From this point on, learn. Record every observation you make about each in its notes.

Through all of this, constant use in the studio (or factory) will never stop surfacing problems (e.g. settling in the bucket, crazing, running, blistering, material issues, etc.). The seriousness of each will determine the level of attack. First, identify the mechanism of the desired fired result. If it is a base recipe plus additions of colorants, opacifiers or variegators, then check if the base of one of the other glazes has a similar surface texture and character. If so, then could the additives in the troublesome one be used with the better base? If not, then it's time to sanity check the recipe and bring out the heavy guns of at least looking at the chemistry. But in Insight-live, you only need to turn on the display of the unity formula (there is nothing else to do). Next, make sure each material in the recipe links to one in the material database (so the calculated formula is accurate). Then compare the calculated unity formula with a limit formula (often a simple sanity check, like with the recipe, quickly spots oxides that are in excess or are short.

Thursday 4th June 2026

A transparent glaze is going satin:

Is it the feldspar and kaolin substitutions?

A potter reports that a switch from G-200 feldspar to Mahavir, and EPK to Imerys kaolin, has resulted in this transparent glaze becoming more satin. Is that possible? Yes. Because this glaze is on a unity formula tipping point.

To see it, you do not need to know how to do glaze chemistry, just how to display the calculated unity formulas side-by-side. My Insight-live shows them here. The material change has little effect. But there is an anomaly: 0.29 MgO. That is magnesia matte territory. The MgO is very likely there to help bring the thermal expansion as low as possible (to avoid crazing). For people who cool their kilns relatively quickly, this fires glossy. But a material change could well affect the cooling rate needed to maintain the gloss. That being said, the potter may also be firing slower, yet attributing the mattness to the materials. Or it could be a combination of both.

This is a popular glaze, among others in the book "Mastering Glazes". In Ron Roy's circumstances, and for many others, it is glossy. But for this potter, a small change (in the recipe materials and also likely in firing) has produced this issue.

Context: MGBase3, Tipping point

Thursday 4th June 2026

Alberta Slip as a functional honey-transparent base:

The glaze I reach for again and again

The functional surfaces on these pieces all employ the GA6-B base honey glaze recipe. On Plainsman native stoneware clays, especially darker burning ones, typical transparents are very prone to micro-bubble and clouding issues. But not this glaze. The likely reason is that Alberta Slip contains coarser particles (it is only processed to 42 mesh), these act as a fining agent.

This glaze brings multiple other benefits:
-It fits Plainsman bodies, all of them.
-It is made from materials mined in Canada.
-The Alberta Slip base produces a thixotropic slurry.
-It acts as a very good base for dark colors and black.

The top mugs are GA6-B inside and out (MNS clay body). The top right has a black engobe under it.
Bottom left: GA6-B inside, GA6-C outside (MNS and Coffee Clay)
Bottom right: L4768E Coffee casting and M340 casting.

Context: This GA6-B glaze is..

Thursday 4th June 2026

Are glazes food safe just because they carry a label?

This Gemini-generated mug could conceivably exist yet carry these labels. Yet experienced ceramic technicians would immediately be suspicious. The glaze is highly fluid and heavily crystallized; both suggest low or very low Al2O3 levels (it is the key oxide that makes glazes durable). If the interior color were produced using a cadmium-containing encapsulated stain, cadmium-release testing would be essential before claiming the ware is food safe. This is clearly engineered for visual effects rather than durability. None of those characteristics prove it is unsafe, but they do mean that labels like "nontoxic" are not substitutes for actual leach testing. A glaze can be made entirely from materials classified as nontoxic and still fail to meet the durability standards expected of functional foodware.

Context: Commercial glazes on decorative.., ASTM D-4236 - Standard..

Thursday 4th June 2026

Should I glaze the outside of this mug now? No!

This bisque mug has been glazed on the inside. But the bisque has absorbed water from that glaze, and this thin-walled mug is now waterlogged as a result (except at the thicker base). It does not have the absorbency needed to build up a thick enough layer of glaze on the outside. Even if it did, the water from the two glazes would wet the bisque so much that its drying time would be greatly extended. This is a problem because the mechanism of attachment of glaze to the body is fragile and works best when the glaze dries quickly. When drying is too very slow, bubbling and cracking often occur (leading to crawling in the firing).

Context: Does bisque ware need.., Glaze thickness

Monday 1st June 2026



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