Javascript must be enabled in the security or content
settings of your browser for this site to work properly

To learn more about cookies search for HTTP cookie at

Click here for information about DIGITALFIRE Corporation

Tony Hansen's Thousand-Post TimeLine

I am the creator of Digitalfire Insight, the Digitalfire Reference Database and ... more

  All | Last 10 | Next 10 | Reset

G2934Y glaze on Standard #112 body at cone 6

Produces an appearance very similar to dolomite-matte-glazed ware fired in cone 10 reduction. The effect would be similar using speckled bodies made by other manufacturers. Pieces made by Tom Friedman.

Thursday 3rd October 2019

A heavily grogged casting body still casts with a smooth surface!

20% 20-40 mesh grog was added to a Pyrax/Kaolin thermal shock body. While the insides of the pieces have a very rough surface, the outsides are smooth! Grogged casting slips have issues with the particle settling during storage and casting, however in this body the grog suspends long enough for a 15 ... more

Thursday 3rd October 2019

Reverse-engineer a commercial transparent glaze to get the recipe

The commercial cone 04 clear brushing glaze on the left works really well on our bodies so I sent it away to be analyzed (about $130). From that information and using my account at I was able to create a recipe, having the same chemistry, employing two Fusion frits (which amazingly ... more

Thursday 5th September 2019

How and where to have a glaze tested to learn its chemical analysis

Here are some of the papers I had to deal with to have a mystery colourless transparent glaze analyzed (so I can calculate a mix of my own materials to produce this chemistry). Since no one test will find all the 13 common oxides that may be present in low temperature colorless glazes I had to order ... more

Thursday 5th September 2019

Trafficked online recipes waiting for a victim to try them!

You found some recipes. Their photos looked great, you bought $500 of materials to try them, but none worked! Why? Consider these recipes. Many have 50+% feldspar/Cornwall/nepheline (with little dolomite or talc to counteract their high thermal expansion, they will craze). Many are high in Gerstley ... more

Monday 2nd September 2019

Can you throw zircopax on the potters wheel? Yes!

These crucibles are thrown from a mixture of 97% Zircopax (zirconium silicate) and 3% Veegum T. The consistency of the material is good for rolling and making tiles but is not quite plastic enough to throw very thin (so I would try 4% Veegum next time). It takes alot of time to dewater on a plaster ... more

Friday 30th August 2019

High LOI materials can turn your glaze into Aero chocolate!

The smooth surface of this blistering glaze has been ground off to reveal how serious the bubble problem really is. If the body or glaze itself is generating gases of decomposition at the wrong time, and the glaze has too little melt fluidity to pass the bubbles, this can happen. Opacifiers ... more

Thursday 8th August 2019

A runny glaze is blistering on the inside of a large bowl

The glaze is running down on the inside, so it has a high melt fluidity. "High melt fluidity" is another way of saying that it is being over fired to get the visual effect. It is percolating at top temperature (during the temperature-hold period), forming bubbles. There is enough surface tension to ... more

Thursday 8th August 2019

White majolica bases have very, very low melt fluidity

This is Linda Arbuckle's base recipe (66% frit 3124, 23% feldspar, 13 kaolin/bentonite, 9 zircon, 4 tin oxide mixed to 1.62 specific gravity). It is fired at cone 05 creating a super gloss. This is applied very, very thickly (double the thickness of what a stoneware glaze would be). Yet notice how ... more

Wednesday 31st July 2019

BEWARE of leaving outsides of functional ware unglazed

This mug is made from the strongest porcelain I have, it is so vitreous that the bare fired surface does not even coffee-stain. So I glazed it only on the inside. That created a time-bomb waiting for hot coffee! Three others did exactly the same. Four other mugs glazed on the outside were fine. Why? ... more

Wednesday 24th July 2019

Contact Us:

Use the contact pages within or outside your account at

Test, Document, Learn, Repeat in your account at

Login to your online account

Chemistry plus physics. The on-line successor to desktop Insight. Get an account for as little as $15. It does so much more.

Conquer the Glaze Dragon With Digitalfire Reference info and software

Still available for Mac, PC, Linux

Interactive glaze chemistry calculations (legacy, no longer supported)

What people have said about digitalfire

• I have been browsing the ceramic materials site with some of the Bastarache articles and their links. Extremely helpful information. Thank you both you and Edouard!

• Abundant thanks on you how much the huge information and useful for me and for domain of pottery and the academic arts and the students.

• 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.

• Your sight ROCKS.

• Thank you for the work you do to improve the work of potters trying to do new things.

• Great resource!!!

• The Tony of digitalfire, wow. I love the digitalfires website, but I thought it cost money to get advice from you.

Click here to see all 191

What people have said about Insight-Live

• First I want to thank you for the service you're providing the ceramics community at large.

• 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.

• Hey Tony, thanks so much for developing such a useful software. I have come to digital fire for countless questions I have had with clay and glazes.

• You have no clue how much this site has inspired and helped me develop my love for ceramics and chemistry.

• 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.

• Thanks for sharing your extensive knowlege with the clay community.

• I am a big fan of your work. I want to thank you for being there when I have needed and hopefully I will be able to carry on without much input from you. I will be renewing my subsrciption soon and I extol the virtues of the program (and now the Cloud version) to everyone that will listen.

Click here to see all 119

DigitalFire Logo

Privacy Policy