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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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The same body works well at both cone 04 and 6!

The same body works well at both cone 04 and 6!

How is this possible? 15% Nepheline Syenite. The unmelted nepheline particles impose their higher thermal expansion on the fired ceramic. It is porous and weaker than stoneware but the glaze (Spectrum 700) does not craze and does not permit the entry of water (the mug is glazed across the bottom and ... more

Thursday 4th April 2019

Mother Nature's Porcelain Mug

Original File: RedMNP.mp4

Wednesday 3rd April 2019

The matteness this glaze develops is dependant on the cooling rate

The matteness this glaze develops is dependant on the cooling rate

This is the G2934Y matte cone 6 recipe with a red stain (Mason 6021). The one on the left was fired using the C6DHSC slow-cool schedule. The one on the right was fired using the drop-and-soak PLC6DS schedule. The only difference in the two schedules is what happens after 2100F on the way down (the ... more

Wednesday 20th March 2019

Transparent and RavenTalc silky matte glazes on black engobe at cone 10R

Transparent and RavenTalc silky matte glazes on black engobe at cone 10R

Clay is Plainsman H450. The L3954N black engobe was applied at leather hard stage (on the insides and partway down the outside). The G1947U clear glossy glaze over it on the inside produces a deep and vibrant hue (left). The inside glaze on the right is GR10-C Ravenscrag silky matte. The outsides are GR10-J Ravenscrag Dolomite matte with a little added cobalt and iron (for blue and brown).

Wednesday 20th March 2019

Difference between oxidation and reduction! GR10-C matte on Plainsman H443

Difference between oxidation and reduction! GR10-C matte on Plainsman H443

Same body, same glaze. Left is cone 10 oxidation, right is cone 10 reduction. What a difference! This is a Ravenscrag-Slip-based recipe on a high-fire iron stoneware. In reduction, the iron oxide in the body and glaze darkens (especially the body) and melts much more. The behavior of the tin oxide opacifier is also much different (having very little opacifying effect in reduction).

Wednesday 20th March 2019

Sourcing Li2O from spodumene instead of lithium carbonate

Sourcing Li2O from spodumene instead of lithium carbonate

Lithium carbonate is now incredibly expensive. 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 did the calculations and got a ... more

Tuesday 19th March 2019

Here is why quartz is good in clay bodies

Here is why quartz is good in clay bodies

The piece on the left is 65% ball clay and 35% nepheline syenite. The one on the right is 65% kaolin and 35% nepheline syenite. Both fire vitreous at cone 6. But the glaze is crazing on the kaolin and not on the ball clay. This is because the ball clay contains significant quartz, that raises the thermal expansion and that puts the squeeze on the glaze and prevent the crazing.

Tuesday 19th March 2019

Functional ware at low fire! Don't dismiss it just yet.

Functional ware at low fire! Don't dismiss it just yet.

These were only fired at cone 04, but they are durable enough to last some time with normal use. The insides have a transparent glaze (Spectrum 700), it is leadless and completely safe. These are great insulators, they keep coffee warm longer than porcelain or stoneware. The feet are glazed so they ... more

Monday 18th March 2019

Which is better for functional ware? Cone 04? Cone 10 reduction?

Which is better for functional ware? Cone 04? Cone 10 reduction?

Not so fast! Cone 10R ware is only strong if the glaze fits. Fortunately this does. But either one will break if dropped on the floor. The stoneware clay has a porosity of 2.5-3%, the earthenware 12%. But the entire base of the orange one is glazed (it was fired on a three-pointed stilt), and the ... more

Monday 18th March 2019

Cheap Amazon glaze mixer, how does it stack up?

Cheap Amazon glaze mixer, how does it stack up?

Make some adjustments and it is usable. First, it is very quiet and has lots of power. The plastic sliders ride smoothly and provide precise adjustability (but the plastic threads might not last). The vertical shaft is stainless steel and the cast iron base is heavy, sturdy, practical. The ... more

Tuesday 12th March 2019

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• This is really cool. Thanks for sending this to my email.

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