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Tony Hansen's Thousand-Post TimeLine

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

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Particle size drastically affects drying performance

Particle size drastically affects drying performance

These DFAC testers compare the drying performance of Plainsman A2 ball clay at 10 mesh (left) and ball milled (right). This test dries a flat disk that has the center section covered to delay its progress in comparison to the outer section (thus setting up stresses). Finer particle sizes greatly ... more

Tuesday 22nd May 2018

Lab testing a clay for its physical properties

Lab testing a clay for its physical properties

SHAB test bars, an LDW tester for water content and a DFAC test disk about to be put into a drier. The SHAB (shrinkage-absorption) bars shrink during drying and firing, the length is measured at each stage. The LDW sample is weighed wet, dry and fired. The can prevents the inner portion of the DFAC ... more

Tuesday 22nd May 2018

Do you know the purpose of these common Ferro frits?

Do you know the purpose of these common Ferro frits?

I used a binder to form 10 gram GBMF test balls and fired them at cone 08 (1700F). Frits melt really well, they do not gas and they have chemistries we cannot get from raw materials (similar ones to these are sold by other manufacturers). These contain boron (B2O3), it is magic, a low expansion ... more

Tuesday 22nd May 2018

At 1550F Gerstley Borate suddenly shrinks! The melt fluidity ball tells us.

At 1550F Gerstley Borate suddenly shrinks! The melt fluidity ball tells us.

These GBMF test balls were fired at 1550F and were the same size to start. The Gerstley Borate has suddenly shrunk dramatically in the last 40 degrees (and will melt down flat within the next 50). The talc is still refractory, the Ferro Frit 3124 slowly softens across a wide temperature range. The frit and Gerstley Borate are always fluxes, the talc is a flux under certain circumstances.

Tuesday 22nd May 2018

Why is that transparent glaze firing cloudy? The balls test us.

Why is that transparent glaze firing cloudy? The balls test us.

G1916Q and J low fire ultra-clear glazes (contain Ferro Frit 3195, 3110 and EPK) fired across the range of 1650 to 2000F (these were 10 gram GBMF test balls that melted and flattened as they fired). Notice how they soften over a wide range, starting below cone 010 (1700F)! At the early stages carbon ... more

Tuesday 22nd May 2018

Tune your matte glaze to the degree of matteness you want

Tune your matte glaze to the degree of matteness you want

G2934 is a popular matte for cone 6 (far left). It is not matte because it is not melting enough or is covered with micro-crystals, it is an MgO matte (a mechanism produces a more pleasant surface that cutlery marks and stains less). But what if it is too matte for you? This recipe requires accurate ... more

Tuesday 22nd May 2018

90:10 Albany:Frit and Alberta:Frit comparison

90:10 Albany:Frit and Alberta:Frit comparison

These are three runs of Alberta Slip being compared with the original Albany Slip. These are ten-gram GBMF test balls fired on porcelain tiles at cone 6. This test shows how the material flows, how much gases of decomposition it generates and how well it allows them to escape. As you can see, they are very similar in melting behavior.

Tuesday 22nd May 2018

Five common frits fired at cone 03 (1950F)

Five common frits fired at cone 03 (1950F)

Five common North American Ferro Frits fired at 1850F on alumina tiles (each started as a 10 gram GBMF test ball and flattened during the firing). At this temperature, the differences in the degree of melting are more evident that at 1950F. The degree of melting corresponds mainly to the percentage ... more

Tuesday 22nd May 2018

Compare fired glaze melt fluidity balls with their chemistry and lights come on!

Compare fired glaze melt fluidity balls with their chemistry and lights come on!

10 grams GBMF test balls of these three glazes were fired to cone 6 on porcelain tiles. Notice the difference in the degree of melt? Why? You could just say glaze 2 has more frit and feldspar. But we can dig deeper. Compare the yellow and blue numbers: Glaze 2 and 3 have much more B2O3 (boron, the ... more

Tuesday 22nd May 2018

What material makes the tiny bubbles? The big bubbles?

What material makes the tiny bubbles? The big bubbles?

These are two 10 gram GBMF test balls of Worthington Clear glaze fired at cone 03 on terra cotta tiles (55 Gerstley Borate, 30 kaolin, 20 silica). On the left it contains raw kaolin, on the right calcined kaolin. The clouds of finer bubbles (on the left) are gone from the glaze on the right. That ... more

Tuesday 22nd May 2018

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What people have said about digitalfire

• Thanks for your website! I found it greatly informative and useful in my research work on high temperature ceramic materials.

• LOVE your site! You have saved me a whole lot of work and research time with your materials data base and comments. I haven't gotten to explore your software yet because I'm in the middle of resolving another mess involving raw materials from a certain large company with sloppy production. We are a small company that is developing a low expansion, thermal shock resistant porcelain for industrial use ... Between our acquired data and some clues contained in your comments we were able to pin point the problem.

• 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.

• Thanks for the fantastic program and service.

• I have thoroughly enjoyed the articles on your web site.

• Hi, I love your work and I would like to participate.

• I have used your web sight to help with information for teaching Glaze Formulation. I have sent my students here.


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What people have said about Insight-Live

• Hey Tony, just like to say thanks for your fantastic site as it has been the best reference guide for my helper and I.

• I should mention beforehand that you, as well as Insight, have become the “go to” reference for all technical aspects of my work and those of other potters I know. It has become an invaluable resource. Congratulations on your academic approach to everything ceramic.

• You are due many complements on your site and software. I usually have your A - Z materials dictionary open in my web browser.

• Yet again, you provide a quick answer not easily found elsewhere (a bowl was befuddling me with wall cracks that never made it to any edges.)

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

• My glazes activities are seasonal anyway. In the summer i make pots in winter I think about chemistry and sit at a PC. I looked at your pricing again and it is indeed reasonable.

• BTW, thanks for creating such a great site.


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