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Tony Hansen's Thousand-Post TimeLine

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


A Cone 6 white engobe works miracles on these dark and buff burning bodies

Left is Plainsman M340. Right is M390. Each mug has been white engobed inside and half-way down the outside. The insides have been glazed using G2926B clear. The inside surface has more depth and has a richer appearance than you could achieve using a white glaze (especially over the dark burning ... more

Friday 23rd June 2017

Iron oxide vacuums up glaze bubble clouds at cone 6

These two mugs are the same dark burning stoneware (Plainsman M390). They have the same clear glaze, G2926B. They are fired to the same temperature in the same firing schedule. But the glaze on the left has 4% added iron oxide. On a light-burning body the iron changes the otherwise transparent glass ... more

Friday 23rd June 2017

GA6A Alberta Slip base using Frit 3249 and 3195 on buff body

The body is buff burning Plainsman M340 (cone 6). The amber colored glaze is 80% Alberta Slip (raw:calcine mix) with 20% of each frit. The white engobe on the inside of mug 1 is L3954A (also glazed inside using transparent G2926B). These frits are producing an amber gloss glaze of high quality. On ... more

Friday 23rd June 2017

A cone 6 clear glaze plus iron vs. Alberta Slip clear base

These two mugs are made from a dark red burning stoneware and fired in a cool-and-soak firing schedule. A white engobe (L3954A) has been applied on the inside and half way down the outside. Both are glazed inside with G2926B whiteware transparent glaze. The outside glaze on the left is the same ... more

Friday 23rd June 2017

P300 and M370 mugs with GA6A Alberta Slip (using Frit 3249)

Rather than the normal 80:20 AlbertaSlip:Frit3134 recipe, this one substitutes Frit 3249 (super low expansion). The glaze is less runny and even glossier. These are fired at cone 6 in a cool-and-soak firing. They survived boiling water:ice water tests without crazing. The finish is dazzling, a ... more

Friday 23rd June 2017

Digitalfire Insight in 1983. On a Macintosh 128K and original IBM PC.

These were the computers that began the revolution. Insight was there!

Friday 23rd June 2017

How to make a ceramic time-bomb

This mug is pinging loudly and literally self-destructing in front of my eyes! Why? The glaze is under so much compression (the inside is pushing outward, the outside inward). Spiral cracks are developing all the way up the side. Small razor-sharp flakes are shivering off convex contours. Why? I ... more

Friday 23rd June 2017

Bi-Clay strips test compatibility between engobe and body

Slips and engobes are fool-proof, right? Just mix the recipe you found on the internet, or that someone else recommends, and you are good to go. Wrong! Low fire slips need to be compatible with the body in two principle ways: drying and firing. Terra cotta bodies have low shrinkage at cone 06-04 ... more

Friday 23rd June 2017

Glazes of the same chemistry: The fritted one melts better

It seems logical (and convenient) to just say that the kiln does not care what materials source the oxides in a glaze melt. Li2O, CaO, Al2O3, SiO2 are oxides (there are about ten common ones). The kiln just melts everything and constructs the glaze from the ones available. Right? Wrong! Things get ... more

Friday 23rd June 2017

I have always done it this way. Why is it not working now?

Are you really sure the problem is with the materials? I had been using an 85% Ravenscrag, 15% frit glaze for many years with no crawling problems. But then it started crawling. I tried mixes with new materials and the old ones. Still crawled. The problem? What was I thinking? An 85% clay glaze is ... more

Friday 23rd June 2017

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Conquer the Glaze Dragon With Digitalfire Reference info and software

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Interactive glaze chemistry calculations.

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What people have said about digitalfire

• I am a builder / developer / consumer of ceramic tiles. You have a sea of information on your site.

• I use Digitalfire almost every day for reference to questions about materials. And as a relative newby to the industry and coming from an art background, my technical knowledge is limited to my own experiences, what I can find online and what is available in books and literature. I just wanted to thank you for all the work you have done for the ceramics community. Your insights and technical knowledge have become indispensable to many in the ceramics community, including me.

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