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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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Measure glaze specific gravity with a hydrometer? Forget it!

Measure glaze specific gravity with a hydrometer? Forget it!

Glazes need to be gelled, have thixotropy. That means these things won't bob up and down to find the right place. The one on the right is completely useless, the scale is too wide. Most glazes need to be between 1.4 and 1.5 specific gravity (40-50 on this scale). That is like reading seconds on the ... more

Wednesday 16th January 2019

Is this your record keeping system?

Is this your record keeping system?

Keeping your valuable notes like this? Recipes? Test results? Are your pictures lost in a cellphone with no keywords or connections to anything? If you test and develop you need to organize in a way that a book cannot do. Like link recipes to each other and other things like pictures and firing ... more

Monday 14th January 2019

Trafficked online recipes waiting for a victim to try them!

Trafficked online recipes waiting for a victim to try them!

Last week a customer came to buy materials to mix these recipes she found online. Then we had a closer look. Many have 50+% feldspar/Cornwall/nepheline with little dolomite or talc to counteract their high thermal expansion, these are guaranteed to craze. Many are high in Gerstley Borate, it will ... more

Monday 14th January 2019

Two G2571A Bamboo color versions at cone 10R

Two G2571A Bamboo color versions at cone 10R

These mugs are Plainsman H450. Both have a black engobe (L3954N) applied to the insides and half way down the outside during leather hard stage (the insides are glazed with Ravenscrag silky matte and G1947U over the black engobe). The bamboo glazes can thus be seen over the black (upper half) and ... more

Monday 7th January 2019

G1947U Clear and Ravenscrag Silky Matte glazes on L3954N black engobe

G1947U Clear and Ravenscrag Silky Matte glazes on L3954N black engobe

Fired at cone 10R. Clay is Plainsman H450. The black engobe was applied at leather hard stage. The clear glossy glaze over it on the inside produces a deep and vibrant hue. The black engobe extends downward on the outside and it greatly darkens the glaze applied over it. On the edges of contours, where the matte glaze is the thinnest, the engobe turns the color almost black.

Monday 7th January 2019

A vitreous sculpture clay. Vitreous enough for functional ware!

A vitreous sculpture clay. Vitreous enough for functional ware!

The chocolate brown burning super-plastic base clay (to which 20% coarse grog is added) matures at cone 6. Yet this is a cone 10R body. The grog stabilizes the fired matrix enough that it stands up in the kiln. And it fires to a dense product that can withstand any weather. Any porosity that can be ... more

Monday 7th January 2019

A cure for long-time Gerstley Borate sufferers

A cure for long-time Gerstley Borate sufferers

These are various different terra cotta clays fired to cone 04 with a recipe I developed that sources the same chemistry as the popular Worthington clear (50:30:20 GB:Kaolin:Silica) but from a different set of materials. They key change was that instead of getting the B2O3 from Gerstley Borate I ... more

Friday 21st December 2018

We fight the dragon that others do not even see

We fight the dragon that others do not even see

There are thousands of ceramic glaze recipes floating around the internet. People dream of finding that perfect one, but they often only think about the visual appearance, not of the usability, function, safety, cost or materials. That resistance to understanding your materials and glazes and ... more

Friday 21st December 2018

How much feldspar to using in a Grolleg porcelain

How much feldspar to using in a Grolleg porcelain

These are porcelains are made using Grolleg kaolin. P700 (Plainsman) has 19% G200 Feldspar and Coleman (popular among potters in the US) has 31% (P700 switches the 12% to kaolin). Although the Coleman porcelain is more vitreous (top right) it is not more translucent. But it is a lot more problematic ... more

Thursday 20th December 2018

The specific gravities on two commercial underglazes might shock you

The specific gravities on two commercial underglazes might shock you

AMACO and Crysanthos. 1.26 (67.5% water) and 1.22 (68% water)! The former is well below their recommended specific gravity of 1.4 (it still paints well but needs more coats, and more time to dry and apply them). Strangely, the Crysanthos, although having a lower specific gravity is more viscous and ... more

Wednesday 19th December 2018

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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

• Your website has been very helpful to me over the past several years. I refer fellow potters to it constantly. Your G1214Z matte glaze formed the basis for the glaze used on my tea bowls.

• I found a link to your great site whilst looking at oxides/effects ... Generally, the website is brilliant and I've already learned a lot. I need to try it out properly before I go ahead and buy the full thing. Looks very tempting, as all the answers are in one place. The testimonials look promising too.

• Thank you so much. This is what a good business looks like; great product, immediate response from the owner no less, and over the top service.

• I would love to take a trip inside of your brain. I am sure that it would be a fantastic light show.

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

• I am very much appreciative of the work you are doing.

• I have joined to millions of others who must absolutely love you and are so thankful to you - I just want you to really know that you have opened up a whole new world to me that I thought was insurmountable - The wealth of information on Digital Fire is most appreciated, and I hope you know that what you have done is really enormous and God sent to potters.


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What people have said about Insight-Live

• Thank you very much for creating these examples and explanations. I am getting a much better understanding for why Frits are so much better. Now that I am digging into InSight-Live and manipulating the chemistry, this documentation is the main place where I can find the facts and suggestions that help clear up my questions. Thank you for creating such a very practical and wonderful upgrade . The interface is so nice and even forgiving. Thank You Very Much,

• Thank you for your time, and I am totally excited that I woke up to an email from Tony Hansen (I’m a big fan)

• I love insight BTW. I have been showing everyone at Alfred how easy it is to do UMF while comparing two recipes next to each other. The up and down toggles make it easy to understand cause and effect. They are also impressed how easily i can switch between my computer and smartphone and maintain all my work and recipes. BTW I just love insight. It has changed my experience and knowledge of glazes drastically.

• Thanks! I look forward to seeing your posts. I have read and printed many things you have posted over many years. Have learned a lot from you.

• 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 so much this info is so great!!

• 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.


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