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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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Two reasons why porcelain recipes need silica

Two reasons why porcelain recipes need silica

This is 70% kaolin and 30% feldspar. The fired body looks very porcelaneous but right out of the kiln the crazing is like this. The thermal expansion of the kaolin:feldspar mix is too low, no ordinary glaze will fit it. The other issue is with the flat particle shape of kaolin. The throwing process ... more

Wednesday 10th October 2018

If your functional ware crazes you absolutely must fix it

If your functional ware crazes you absolutely must fix it

This glaze and body and not compatible, the body thermal expansion is too low and the glaze it too high. It not only creates a germ zoo but severely weakens the piece. I tapped this lightly with a spoon about 1-2 cm below the rim, doing so repeatedly. Right from the start the piece had no ring, no ... more

Tuesday 9th October 2018

Another reason that Insight-live.com exists

Another reason that Insight-live.com exists

First, I need to record this as a recipe in my account at insight-live.com so it can be printed at any total, documented with pictures of it on different clays, firing schedules and how they affect it, general notes. And be accessible from anywhere with any device. Then I need to start working on ... more

Friday 21st September 2018

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 (L3954J) 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

Friday 21st September 2018

Three visual glaze mechanisms make this piece unique

Three visual glaze mechanisms make this piece unique

Mechanisms" are specifics about the glaze application or preparation process, the materials, the chemistry or firing schedule that produce a specific visual effect. This is fired at cone 10R. It is made from a buff stoneware, Plainsman H550, and has L3954J black engobe on the inside and part way ... more

Friday 21st September 2018

The matte version covers better, looks better

The matte version covers better, looks better

This is G2934 matte (cone 6) and G2931K glossy base recipe having the same Cerdec yellow encapsulated stain been added (about 10%). You really need to see these side-by-side to appreciate how much richer the silky matte version looks (and feels). AMACO has popularized the bright glossy transparent ... more

Friday 21st September 2018

A mug cracks before your eyes because of glaze compression

A highly vitreous, thin walled mug is glazed inside-only. The glaze has a thermal expansion that is too low and it is under compression, pressing outward. A tap with a spoon is enough to trigger a sudden crack. It opens under the pressure. Had it been glazed on the outside also it would likely survive, but this test still indicates that it would be better to raise the expansion a little.

Friday 21st September 2018

Program your firings manually, calibrate the final temperature

Program your firings manually, calibrate the final temperature

Here is an example of our lab firing schedule for cone 10 oxidation (which the cone-fire mode does not do correctly). We need it to actually go to cone 10, the only way to do that is verify with a cone (self supporting cones are the only accurate way). Then make a note in the record for that schedule in your account at insight-live.com.

Thursday 30th August 2018

Measuring glaze slurry specific gravity

Measuring glaze slurry specific gravity

This is the easiest way to measure the specific gravity of a glaze if it is not in a container deep enough to float a hydrometer (or if it is too thick to float it properly). Just counterbalance the empty graduated cylinder to zero, fill it to the 100cc mark and the scale reads the specific gravity ... more

Wednesday 29th August 2018

Measure glaze specific gravity with these? Forget it!

Measure glaze specific gravity with these? 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 29th August 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

• I'll be reading and studying for a while, but what is so great is that the information is now right at my finger tips anytime that I need it - its all so very interesting - I never thought that chemistry would ever be interesting, - and I know now very soon I too will be able to slay the glaze dragon!

• I'm still reading about expansion and some of what you explained to me is in this article by digital ... so much lay men terms and analogies makes its more viewable to the mind and understandable... thanks - I continue to say thanks... Tony.... :)

• Thanks again for all you have done for the pottery world!!!

• 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 want to know more about the ceramics field and I see your outfit as being the most proactive in having vital information in the field.

• I knew nothing about chemistry, so I have already learned a great deal from the information you've so generously provided on-line.

• I have been a teacher of ceramics for twenty years and have always been annoyed with what you call traveling glazes. Tom's Blue, Randy's Red, etc. have been taken from who knows where, are out of context and without history or understanding as you point out.


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What people have said about Insight-Live

• Anyway I thank you for your efforts in putting together this wealth of ceramic science in this accessible manner.

• 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.

• Had quite quite a few problems learning to enter recipes.

• I discovered your website after trial and failure for 35 years. WOW ! The questions you have answered for me and the knowledge are immeasurable To think I am going to get past the Science and onto the Art makes me near giddy. Your site is amazing. My college age kids are going to be dazzled I did this. Every single college ceramic studio should know about your site. I want to tell them!

• Thank you so much for this wonderful resource you have created! I have found all of the information in the Digital Fire database as well as Insight to be incredibly helpful tools in the ceramic world.

• Thank you again for the amazing website and wealth of information!!! InsightLive is proving to be an incredible asset as well!!!

• Love Insight-live. Have been using it a few months and now that I know my way around a bit, I have come to rely on it. Love having a web based program, since I bounce between Windows on several machines and also a Chromebook.


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