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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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What is the temperature difference between these two cones?

Four degrees F. I was consistently getting the cone on the left using a custom programmed firing schedule to 2204F. However Orton recommends that the tip of the self supporting cone should be even with the top of the base, not the bottom. So I changed the temperature to 2200F and got the cone on the right.

Wednesday 24th July 2019

Cone 6 Fluid-Melt Transparent Glaze - Jackpot!

In 2015 we did a project comparing common cone 6 fluid-melt base glazes, picked a favourite (Panama Blue) and fixed it's slurry issues and crazing. Fluid-melts almost run off ware when applied thick, but they host stains & opacifiers to produce super-gloss, super-brights. That recipe, G3806C, has ... more

Monday 22nd July 2019

Sourcing Li2O from spodumene instead of lithium carbonate

Lithium carbonate is now incredibly expensive. The glaze on the left employs it. But I was able to source the Li2O from spodumene instead. Spodumene has a complex chemistry, but the oxides that it contains (other than Li2O) are those common to glazes anyway. Using my account at insight-live.com, I ... more

Monday 22nd July 2019

Tin Oxide is expensive, do not waste it by not mixing well

This is a cone 04 glaze on a terra cotta body. Two 300-gram test batches were made. Both have 5% tin oxide added. The one on the left was high-speed propeller-mixed for 10 seconds on a closed container. That was not enough, small agglomerates appear as white specks floating in the glass. The one on ... more

Saturday 20th July 2019

The difference propeller-mixing a glaze can make

The glaze has 5% added titanium dioxide. These were fired at cone 6. The titanium in the one on the left remained agglomerated, it did not disperse in the slurry during hand mixing (the agglomerates can be seen as white particles floating in the glass). On high-speed propller-mixing the effect on ... more

Saturday 20th July 2019

CMC gum solutions can go bad

That is why glazes containing CMC often need a biocide if they are going to be stored for extended periods. We made this one. The gallon jar of Laguna gum solution sitting next to this did not go bad, that means they have added some sort of anti-microbial agent.

Saturday 20th July 2019

This flow tester proves the colorant is not fluxing or bubbling the glaze

These glazes are the same (G3806G), except the one on the right has 3.5% copper carbonate added. Copper is commonly thought to flux glazes, making them melt more. But in this case, the clear base is running just as much as the stained one. And I was suspicious that the micro-bubbles in the glass ... more

Saturday 20th July 2019

This cone 6 black glaze looks glossy until placed beside the cone 04 one

The cone 6 one is on the left, it contains about 25% frit. Both are colored using a black stain. That low fire glaze on the right has a high percentage of frit, likely more than 80%, that is the main reason for the beautiful surface. Frits are really fantastic, and standard practice in industry. ... more

Saturday 20th July 2019

Lemon Leaching Test on a Copper-containing Glaze

This was left for 24 hours. Wrapped in stretch wrap. Then the surface of the glaze was inspected under a lamp to detect any differences between the lemoned and non-lemoned surfaces. Lemons are highly acidic. This glaze passed because the base recipe, G3806N, was methodically developed so that it has plenty of Al2O3 and SiO2 (in the fired chemistry) to build a stable glass.

Saturday 20th July 2019

A glaze and underglaze are flaking off. Why?

At low temperatures glazes are not stuck on nearly as well as for stoneware and porcelain. One of the ways to compromise the bond is to put a layer of refractory material, for example certain underglazes, between the body and glaze. It is kind of like painting something that is dirty, the paint ... more

Monday 8th July 2019

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Test, Document, Learn, Repeat in your account at insight-live.com

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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'm excited to get started learning how to use the program. I've drawn much from your online glaze chemistry information over the years, and now I hope to apply some of that knowledge effectively.

• My pleasure -- your database is a wonderful set of reference info, and if I can help make it even more accurate and/or complete, I'm happy to do so.

• I think Glaze chemistry is an extremely under-appreciated and under-estimated field of science.

• What an awesome list of videos you have here, and the info on your site is invaluable.

• This is a excellent site for Ceramic colors and containing very good knowledge for Ceramic coloring agents. Thank to Digitalfire Ceramic Oxides Directory.

• Great customer service!!

• Firstly, I want to thank you about this very good site in the net which helps very much in the development of the ceramics industry.


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What people have said about Insight-Live

• Dear tony: Nice work keep it up!

• First, I want to thank you for all the help we got from Digital Fire; thank you very much for this huge work and to share it like that.

• Tony, I looked at Insight Live today more carefully. It is quite an accomplishment! Congrats to you!

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

• WOW, WOW, WHAT GREAT INFO! thankyou! I am going to pass your site on to someone i know who is more keen on the science of glazes, than the potting, unlike me... she will love your test works and pics Wow! Thanks again.

• Thank you for your very informative website - it is a real help to one who has spent 40 years potting.

• 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.


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