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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.

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What people have said about Digitalfire

  • I've read it cover to cover (and some sections two or three times) and I wish more than ever that I had read it before the eighteen months of mixing and testing that I've done.
  • I downloaded Insight as a result of buying your book. WOW, I love that book, real information.
  • As a new potter, your website has been an incredible source of information for me, both in tips, recipes and things to ponder. I know I can speak for a few others when I say please keep posting as the information is highly valued.
  • This site is very informative. If the average layperson were to read this site, they would be blown away, and in my case, inspired to learn more. I like to give credit where credit is due, and this site rocks.
  • I'm finding the magic of fire fantastic!
  • I love your site and am so grateful for all you have done to help with glaze formulation/safety.
  • Tony's site is really full of exceptional technical information.
  • Thanks, your website is a wealth of information for me and my students.
  • You are so good for me. Find a stumbling stone and in a moment the path is easier.
  • Just wanted to thank you for the timeline. I check for new posts every day and think it is a brilliant way for you to keep me thinking about clay and glaze chemistry.

What people have said about Insight-Live

  • Tony, you're a gentleman and a scholar. Thanks for the information. I'm a self-taught potter living in Hansville, WA. could not have done it without your scientific approach and papers.
  • I've literally been using your website for Glaze chemistry since I was a neophyte in Glaze making I didn't think you were a singular person I thought it was a corporation of people who made the website.
  • We've referred to your site so many times over the last year and I can't express how incredibly valuable a resource it is.
  • First, I want to say that I admirer your work. Your professional approach and your website are inspiring!!
  • Thanks Tony for your excellent stuff. I am learning a lot. Its of complete knowledge at ease. God bless you !!!
  • Tony, I owe you a tremendous debt of gratitude. In art school, I got a thorough grounding in ceramics -- in a macro sense. Micro, not so much. You, then, are the professor who is helping me to complete my education, via Digitalfire -- truly a Phenominal piece of work.
  • I take this opportunity to appreciate your efforts in sharing all the information related to ceramics on the Digital Fire website. It is really helpful. I am from India. We work towards reducing mining for natural resources by 60% through making (fired) recycled ceramic products.
  • I wanted to let you know that I greatly appreciate all the knowledge you have shared with me over the years. Its made an enormous difference in the quality of my work.
  • I am a production potter and I have been using your website for information, and I have made many improvements from articles posted on this site.
  • I'm a professional potter from Western Australia with a 30 year career - self taught. I came across Digitalfire when researching raw materials - an incredible resource you've put together!
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.

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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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