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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

  • I would also like to say thank you for providing the information about glaze's that you have on your websight. I have been formulating glaze for 20+ years, read practicaly every book on glaze & glass and your web page's had better information than any book.
  • What I am looking is the operation of roller kiln and what changes body undergo at what temp & why in kiln. Also general defects in vitrified body after kiln & likely reason for that. I am learning a lot about clay body formation from your site. It's really a gift for a people like me.
  • I am at the point where I'm ready to go beyond the hit or miss approach to finding workable glazes. So far I'm finding you book most helpful. It is clearly written, and most of all understandable for a non-chemist like myself. I look forward to trying the Insight program soon. Your website is a great source of information. Thanks and keep up the great work.
  • I want to comment. This is the most complete site about ceramics that I have ever seen.
  • Thanks for your time and making the most informative website I have come across!
  • First, let me thank you for creating such a wonderful, informative, and comprehensive site. I know that I will spend many a long hour pouring through your pages.
  • I must say I am amazed by what I saw here. I am even more surprised to see so much of cermaic material stuff here.
  • So far your site has been a blessing in that I don't feel I have to go anywhere else to get my information, you have it all (at least as far as I can see now) right here in one place. I am new to glaze formulation but not to ceramics. Recently I have had a crazing problem with a certain clay body I am using and as of today I feel confident I can solve it using information on your website. It is I who want to thank you for making such a clear and concise information depository that can be used by all, especially those new to glaze chemistry.
  • Just wanted to share the good news with you. Couldn't be doing it without all the help you have given us over the years!
  • When I first opened the program I thought I would never know how to use it and did not open it again until last week. I have been watching some of the tutorials and those made it very easy to understand and work with Insight. Also your website has been very helpful for a project I am currently working on (and in general the understanding of glazes). So thank you for all the information you have collected and made available.

What people have said about Insight-Live

  • I am doing pottery now for abut 40 years and nowhere else I could find such an extensive, complete, to the point collection of information than in Digitalfire!
  • I just wanted to say, thank you! I’m relatively new to pottery, taking a mostly self-taught approach and I’m at the stage where glazing is in my mind. I don’t want to be (and can’t see myself ever) buying glazes from commercial suppliers. I want to learn my craft with glaze as much as I do with my clay preparation and pottery making. I’ve seen “the dragon” and been uninspired by so much of what I find online and to be honest, in many glaze books. It seems more popular to try and present a mass of glaze possibilities than to offer a learning experience beyond being told a glaze needs a melter, a refractory and a glass-maker. Enough to offer a very basic understanding, but nothing upon which to build the understanding that will allow some degree of mastery (or at least influence) of your glaze making. I am so pleased to have found digitalfire.com. You’ve shown me exactly how to approach and understand glazing, giving me the foundation for approach I sought. I was thinking of base glazes and what you’ve shown me about working on from those is fantastic and exactly what I was looking for. To have a reliable base glaze to modify and develop to meet different needs; to understand how to shift a melting point or adjust the surface gloss; to come to know how the mechanisms in a glaze and understanding them gives me the route to creating glazes that realize my intentions - wow! I can’t thank you enough. Rather than having to form a dumb reliance on a book of recipe cards and a bunch of website bookmarks (which I wasn’t wanting to go for) you’ve given me the foundation for a lifelong development and understanding of the glazes I will make, that will become “my” glazes. You have really opened my mind to the whole subject and it doesn’t seem to be a problem that I’m no scientist or chemist. You’ve shared your knowledge in a way that is completely approachable and remarkably easy to understand for someone without any kind of science/chemistry background.
  • This is really cool. Thanks for sending this to my email.
  • Cannot imagine what I would do without my Insight-live.
  • 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
  • I want to first tell you that your site is amazing. i love the approach, the attitude, and the incredible information. the fact that you share so much of your information to the public is truly wonderful. I recenly fell in love with ceramics and set up a home studio.
  • This article was very interesting and prompted me to write to thank you for the fantastic resources of DigitalFire and Insight-Live. I'm a fairly new potter---both to the craft and glaze chemistry---and your scientific approach is an absolute treat compared to vague advice often trafficked outside of industry. Furthermore, Insight is a wonderfully powerful tool which has defined how I approach testing and analysis of clay and glazes. It's incredibly refreshing to have information usually buried under the expense and jargon of industry journals and textbooks freely available.
  • I would like to honour my commitment to the great work you do. It is an invaluable resource! Just a huge thank you!
  • I am eternally indebted to you for all that you have done to advance the technical abilities of non-industrial pottery! I love using Insight.
  • I am a high school senior AP ceramics student investigating glaze chemistry and rheology. I spend a great deal of my free time browsing the digitalfire reference library, and would have never developed the passion I have for ceramics chemistry had I not come across it.
April 2026: We are continuing a major code rewrite, please be patient regarding any issues. If any page is not working for a period of hours, please contact us. Thank you.

Monthly Tech-Tip from Tony Hansen

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Blog

Instagram is the free street sign.

Your free website is the studio.

Yes, it is still possible to host a free WordPress website on an 1GB Amazon EC2 free-tier instance. The method is new: ChatGPT answers every question, takes you step-by-step. You'll need a domain (e.g. mypottery.com, as little as $5-20). It is yours and signals permanence, confidence. Instagram is built for quick scrolling, followers are "rented attention". But your website content stays where you put it, no algorithm decides who sees your work. It can explain, tell a story for each piece, teach, organize and classify. It can tell search engines what search terms you want to be found for (e.g. “pottery classes near me”). People can discover you. Install the Stripe and a shipping plugin in WordPress and your site can take orders, calculate shipping, make invoices, collect payment, provide tracking. A website lets you collect emails and contact and notify people directly.

This picture, by ChatGPT, shows how ready it is to help you. I recommend manual server configuration (Apache/Nginx, MySQL, PHP) following ChatGPT instructions. ChatGPT will help you with server updates, security patches, and database management.

Context: An entire website created.., WordPress

Wednesday 29th April 2026

Joining rules are different

When clay is soft and plastic

This woman has quickly laid coils of plastic clay on top of each other, in a conical shape. Then she simply begins throwing, centering, compressing and even verticaling the walls on the first pull. Since joining stiffer clay elements, as done in typical hand-building, can be a time-consuming elaborate process, how can this potter just ignore that?

-The clay is quite soft, but very plastic (evident in that the potter dangles the coils like a rope, yet they don’t break, and that she can make such large pieces).
-The coils are rolled on a wet table, generating slip on their surfaces. The plasticity means the surfaces are sticky.
-The piece being made is large and walls are thick.
-The mere act of applying pressure and thinning the wall also joins the coils.

Context: The incredible plasticity of.., Video Throwing a large.., Plasticity

Tuesday 28th April 2026

Does this poodle belong in this team?

Does the frit you use belong in your glaze recipe?

In industry it is normal to use frits whose chemistry is either unknown or approximate provided. The manufacturer has designed them for a specific use, so in many cases they comprise 80%+ of recipes used for that purpose. However potters more commonly use them as minor additions to recipes, they source needed oxides to the oxide formula (instead of raw materials).

Substituting a new frit into a recipe, without paying any attention to how its chemistry compares, is like adding a dog of unknown breed to a team. Knowledge of the breed is needed to know what good and bad it will contribute to the team. It’s a dog, but is it a sled dog? Ceramic glazes fire the way they do because of their oxide chemistry. Frits contribute oxides. Not knowing the chemical makeup of a key ingredient your recipe robs you of the single biggest DIY tool for understanding the fired properties: glaze chemistry.

Context: Frit, Glaze Chemistry

Monday 27th April 2026

DIY glazes can do something commercial ones cannot:

Go on evenly, in one coat and dry in seconds.

Commercial brushing glazes are laced with CMC gum to make them paint on thin and dry slowly. Why would anyone want that? Layering. Brushing on layers takes time and it is difficult to get even coverage, but it justifies brushing up the prices also!

What if you are not a "layer slayer" and want the opposite of all of that: Go on thick enough at one go, dry in seconds and apply super even. DIY potters have that ability by making thixotropic dipping glazes. You cannot buy these because the gum kills thixotropy. Thixotropic glazes are fluid in the bucket but gel after a few seconds of standing. This enables really good dipping properties - the gelling enables the glaze to stay in place upon extraction from the bucket. This picture demonstrates how such glazes hang on to even a non-absorbent and wet surfaces.

Bottom: Extreme thixotropy. The spatula is held vertical by gelling only. Yet when this slurry is put in motion, it is fluid!
Top left and right: These spatulas were slowly extracted and the engobe and glaze just hang on in a perfectly even layer. On a bisque surface, the glaze dries quickly, within seconds. And the engobe hangs on to leather hard ware for perfect coverage, even around sharp contours.

Context: Layer slayers and jar.., Here is my setup..

Monday 20th April 2026

High tension porcelain insulators

Not like the porcelain you use for pottery

Electrical insulators most often employ aluminous porcelains. Like sanitaryware and tableware (mullite porcelains), feldspar still forms some glass, but the microstructure of electrical porcelains is dominated by angular, size-controlled, alumina grains. Only a small amount of mullite forms. The result is a matrix having much better mechanical and dielectric strength, better insulating properties and resistance to thermal shock. How can this be affordable given that calcined alumina is many times more expensive than other common porcelain ingredients? When producers are already extremely careful to meet specifications, rejects are low enough that the added cost of alumina is acceptable given the performance gains.

What about the glossy brown glaze? Brown hides dirt, dust, and industrial grime. Slight variations in firing are less visible and the glassy finish causes rainwater to form discrete droplets rather than a continuous conductive film. The Iron-oxide-based brown is self-opacifying so it does not require zircon. And it is highly resistant to uV degradation and compatible with the chemistry needed to achieve glaze compression (to minimize crazing).

Context: Porcelain Insulators

Monday 20th April 2026

Faux majolica next level: Stoneware!

But the glaze is crawling under the colors.

The original Italian majolica ware was red earthenware with a thick layer of tin-opacified glaze vibrantly brush-decorated using single-strokes of watery metal oxides. The water-color of ceramics. But tin oxide is no longer affordable. And ceramic stains are better. And no one uses lead glazes. So all majolica-like ware made today is actually “faux (false) majolica”. These test samples take the “faux” to the next level: Stoneware with a zircon-opacified white glaze. But almost all are crawling. If this happens for you ask these questions:

Is the glaze re-wetable? Dipping glaze recipes often are not, especially if they fail sanity check (e.g. are over-clayed or under-clayed).
Base coat dipping glaze better survive the rewetting of a second layer?
Mixing them as a brushing glaze give maximum insurance.

What did they look like when the overcolor dried? Cracks are sure indicator or crawling.
Were you painting pure stain or metal oxide (mixing with water only)? Don’t do that. Water color paint uses gum Arabic, pottery colors need to be in a stain medium (which often has CMC gum).

Context: Glaze large bowls inside-and-out.., The secret to brushing.., Stain Medium, Crawling

Monday 20th April 2026

Alumina parts are ceramics on steroids!

In terms of hardness, wear resistance, and high-temperature stability, alumina ceramic is far superior to even the strongest mullite porcelain. Such porcelains are mixes of kaolin, feldspar and silica. Alumina parts are just micron-sized calcined alumina powder fired to an incredible cone 30 or more, often held there for days! The powder is mixed with binders and formed by pressing or injection molding. Precision "green machining" is also used (while parts are chalky). With super fine particle size, high purity, dense packing and prolonged firing, surfaces can be very white and so smooth they are glossy (e.g. spark plugs are not glazed). While parts can even be translucent they are not vitrified, no glass is developed during firing. Rather, they are sintered - the fine particles fuse into a material approaching diamond hardness.

Context: Calcined Alumina

Friday 17th April 2026

A light bulb moment in solving bubble clouding:

The same black engobe with two transparent glazes.

A bubble clouding transparent glaze

This is a buff stoneware body, Plainsman M340. A L3954F black engobe was applied inside and upper-outside at leather hard. The piece was fired at cone 6 using the PLC6DS schedule. The inside, totally clouded glaze, is G2926B. Outside is GA6-B Alberta Slip amber transparent. This inside glaze is crystal-clear on other bodies (and on this one without the black engobe). The black stain in the engobe appears to be the issue. How?

Underglazes (or engobes) become a semi-dense layer and impede LOI by slowing gas diffusion. If the glaze then melts early and lacks viscosity, remaining channels of escape are sealed (increasing bubbling dramatically). Double-melt interfaces can form between vitreous engobes and glaze when the former softens, the clear glaze begins melting. Gases get trapped at the boundary, being generated at the exact wrong time during the firing.

Look at the outside amber transparent glaze, GA6-B. Although also early melting and on the same engobe, it has very little micro-bubble clouding! Why? It contains a lot of Alberta Slip, a material that is not finely ground like others. Particles across the range from 60-200 mesh are present; these are likely acting as a fining agent that enables bubble merging. The larger bubbles break at the surface because of sufficient melt mobility and lower melt surface tension.

Context: Thick application clouds a.., Glaze bubbles behaving badly.., Zircopax as a fining.., 2 Copper carbonate in.., Fining Agent, Glaze Bubbles, Clouding in Ceramic Glazes..

Thursday 9th April 2026

Why this copper glaze does not micro-bubble or craze:

High cone 6 melt fluidity, low surface tension, MgO

This green is not just a typical transparent cone 6 glaze with 2% copper carbonate added (and 2.5% tin oxide). That outer glossy glaze accommodates the copper without micro-bubbling or crazing because of its lower melt surface tension. In such glazes, significant MgO (a super low expansion oxide) can often be tolerated without losing gloss. This is a light bulb moment. Fully 0.15 molar of MgO are present here. This is the "matting oxide"! Yet the glaze is still hyper-glossy!

The above factors are enough. But if this were used in industry, technicians would fix additional issues: The very low initial melting temperature (from 37% very early-melting frit in the recipe). That traps LOI bubbles unnecessarily. Raising the ZnO and sourcing as much of the B2O3 and KNaO as possible from later melting materials and/or frits.

The porcelains are Plainsman P300 and M370. The liner glaze is G2926B, it is a gloss but has a much lower melt fluidity, it is a functional transparent whose main job is to fit the body and be hard and durable. The outer glaze is G3806C.

Context: G3806C, 2 Copper carbonate in.., Fluid Melt Glazes

Wednesday 8th April 2026

Specific gravity using a scale and graduated cylinder:

It doesn't matter how high you fill it

Slurry in graduated cylinder

Counterbalance a graduated cylinder on a 0.01g scale and pour in some slurry. Fill it to any level that does not exceed the weight the scale can handle. Divide the weight by the volume. In this case, it weighs 60.6g and the volume is 41. That calculates to about 1.47 specific gravity. The higher it is filled, the higher the quality of the graduated cylinder and the better you are at reading the level, the more accurate the measurement will be. In this case, I just need an approximate measure. After adding more water to this glaze, I will measure again, filling it to near the 100cc level. I have to use a plastic cylinder because our glass one is too heavy for this scale to handle (its max is 200g).

Context: Measure specific gravity using.., Are cheap plastic graduated.., Specific gravity

Wednesday 8th April 2026



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