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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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This pitcher is oozing a black goo after water sat in it overnight

This pitcher is oozing a black goo after water sat in it overnight

Even after two weeks it is still sticky. This was purchased at an import store. What could this black goo be? It is likely a sealer that they use to make the porous clay water tight, perhaps an organic sugar. The clay is porous (and thus also weak) because they want to save energy by firing their ... more

Saturday 21st April 2018

Better to mix your own cover glazes for production?

Better to mix your own cover glazes for production?

Yes. In this case the entire outside and inside of the mug need an evenly applied coat of glaze. In production, it would not make sense to attempt this by painting. For these reasons: Cost, quality, convenience. The right pail has 2 gallons of G2934 base with 10% Cerdec yellow stain: $135. Cost of ... more

Tuesday 17th April 2018

Absolutely jet-black cone 6 engobe on M340

Absolutely jet-black cone 6 engobe on M340

This is the L3954B engobe recipe but it has 15% Mason 6600 black body stain (instead of the normal 10% Zircopax for white). There is no cover glaze, yet it is durable and absolutely coal black (so a lesser stain % is possible). We have updated the mixing instructions at PlainsmanClays.com and ... more

Friday 13th April 2018

Stain-based black engobe is clean to use!

Stain-based black engobe is clean to use!

Stains are fired, inert particles of a relatively large ultimate size. Unlike that, raw oxide powders, like iron or manganese, have much finer sizes and are thus extremely dirty to use. This plaster slab is being used to dewater these 15% black engobes for shrinkage testing. The slurry on the right ... more

Thursday 12th April 2018

The difference between vitrified and sintered

The difference between vitrified and sintered

The top fired bar is a translucent porcelain (made from kaolin, silica and feldspar). It has zero porosity and is very hard and strong at room temperature (because fibrous mullite crystals have developed around the quartz and kaolinite grains and feldspar silicate glass has flowed within to cement ... more

Monday 9th April 2018

Roasting Alberta Slip at 1000F

Roasting Alberta Slip at 1000F

Roasted Alberta Slip (right) and raw powder (left). These are thin=walled 5 inch cast bowls, fired to 1000F and held it for 30 minutes. Why calcine? Why 1000F? Because Alberta Slip is a clay, it shrinks on drying. Roasting eliminates that, a 50:50 raw:roast mix works well for most recipes having ... more

Thursday 29th March 2018

Alberta slip and Ulexite at cone 6

Alberta slip and Ulexite at cone 6

90% Alberta Slip (which is a mix of half and half raw and calcine) and 10% Ulexite fired at cone 6. A dazzling fluid dark amber transparent. You could also do this using a high-boron frit.

Wednesday 28th March 2018

Will this crawl when fired? For sure!

Will this crawl when fired? For sure!

This high-Alberta-Slip glaze is shrinking too much on drying. Thus it is going to crawl during firing. This common issue happens because there is too much plastic clay in the glaze recipe (common with slip glazes). Clay is needed to suspend the other particles, but too much causes the excessive ... more

Wednesday 28th March 2018

The rutile mechanism in glazes

The rutile mechanism in glazes

2, 3, 4, 5% rutile added to an 80:20 mix of Alberta Slip:Frit 3134 at cone 6. This variegating mechanism of rutile is well-known among potters. Rutile can be added to many glazes to variegate existing color and opacification. If more rutile is added the surface turns an ugly yellow in a mass of titanium crystals.

Wednesday 28th March 2018

The magic of zircon in de-bubbling a glaze with stain addition

The magic of zircon in de-bubbling a glaze with stain addition

The cone 03 porcelain cup on the left has 10% Cerdec encapsulated stain 239416 in the G2931K clear base. The surface is orange-peeled because the glass is full of micro-bubbles that developed during the firing. Notice that the insides of the cups are crystal-clear, no bubbles. So here they are a ... more

Tuesday 27th March 2018

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What people have said about Insight-Live

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• I love your software and I really appreciate you being there when I need help. Keep on being amazing. I am still enjoying insight every day. You were right - having it in the cloud is a huge advantage.

• BTW, thanks for creating such a great site.

• 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.


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