Tony Hansen's Thousand-Post TimeLineI am the creator of Digitalfire Insight, the Digitalfire Reference Database and Insight-live.com. ... more 
Glossy blacks are best made adding a black stain to a quality base transparent
The glaze on the left is called Tenmoku Cone 6 (a popular, and old, CM recipe). It is 20% calcium carbonate, 35% Custer feldspar, 15% OM4 Ball Clay and 30% silica, 10% iron oxide. If you have any experience with glaze you will note two things that a fishy here: There is no boron, lithia or zinc
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Context: Identifying Glaze Mechanisms, Glaze Durability, Melting Temperature Saturday 29th October 2016 
G2931F Ulexite-based transparent bubbles, G2931K frit-based version does not
I melted these two 9 gram balls on tiles to compare their melting (the chemistry of these is identical, the recipes are different). The Ulexite in the G2931F (left) drives the LOI to more than 14%. That means the while the ulexite is decomposing during melting it is creating gases that are creating
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Context: G2931F - Ulexite High Expansion Zero3 Clear Glaze, G2931K - Fully Fritted Version of Zero3 Clear Glaze, LOI, Glaze Bubbles, Frit Friday 28th October 2016 
Glaze melt fluidity comparison between G2931F and fritted G2931K show the effect of LOI
These two glazes have the same chemistry but different recipes. The F gets its boron from Ulexite, and Ulexite has a high LOI (it generates gases during firing, notice that these gases have affected the downward flow during melting). The frit-based version on the right flows cleanly and contains
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Context: G2931F - Ulexite High Expansion Zero3 Clear Glaze, G2931K - Fully Fritted Version of Zero3 Clear Glaze, GLFL Glaze Melt Flow, LOI, Frit, Glaze Bubbles Friday 28th October 2016 
A tiny percentage of blue stain in a porcelain has amazing power
The top porcelain bar has only 0.07% Mason 6336 blue stain added (vs. none in the bottom bar). This is a low fire frit-ware body fired at cone 03 in oxidation. At a slightly lower percentage (e.g. 0.05%) this porcelain will have the same color as a cone 10 reduction one (when covered with a transparent glaze).
Context: Stain 6336, Porcelain Friday 28th October 2016 
A clay that has negative shrinkage during the glaze firing
It seems impossible but that is what happens with this one at cone 03. This is a native material that was found on the banks of the South Saskatchewan river near Hayes, Alberta (and brought to me for testing). Even when fired to maturity (around cone 2) it still has 10% porosity! This specific
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Context: SHAB Shrinkage/Absorption, Firing Shrinkage, Porosity Friday 28th October 2016 
G1947U cone 10R transparent vs. G2931F cone 03 transparent
The mug on the left is Plainsman P600 (a #6 Tile kaolin based porcelain). The other is Zero3 Porcelain, fired at cone 03 (New Zealand kaolin plus frit). Alone the P600 mug looks good, but beside the Zero3 it looks drab. It is grey and not clearing the bubble clouds over the underglaze. The Zero3
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Context: G2931F - Ulexite High Expansion Zero3 Clear Glaze, L3924C - Zero3 Porcelain Experimental, G1947U - Cone 10 Glossy Transparent Base Friday 28th October 2016 
G2931K Zero3 transparent glaze on Zero3 Fritware Porcelain
This is an all-fritted version of G2931F Zero3 transparent glaze. I formulated this glaze by calculating what mix of frits must be employed to supply the same chemistry of the G2931F recipe. The mug is made from the Zero3 porcelain body (fired at cone 03) with this glaze. This glaze fits both the
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Context: G2931K - Fully Fritted Version of Zero3 Clear Glaze, L3924C - Zero3 Porcelain Experimental, Transparent Glazes, Low Temperature Glaze Recipes Friday 28th October 2016 
How can you test if an engobe fits your clay body?
This is part of a project to fit a fritted vitreous engobe (slip) onto a terra cotta at cone 02 (it fires harder there).
Left: On drying the red body curls the bi-clay strip toward itself, but on firing it goes the other way!
Right: Test bars of the white slip and red body compare their drying
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Context: Slip, Firing Shrinkage, Majolica, Engobe Thursday 27th October 2016 
Low fire nirvana: Use commercial underglazes but make your own clear over glaze
Decorate ware with the underglazes at the leather hard stage, dry and bisque fire it and then dip-glaze in a transparent that you make yourself (and thus control). These mugs are fired at cone 03. All have the same transparent glaze (G2931F), all were decorated with the same underglazes. Notice how
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Context: G2931F - Ulexite High Expansion Zero3 Clear Glaze, Plainsman Zero3 red body, engobe, glaze and firing schedule Wednesday 26th October 2016 
Are frits partially soluble? Yes, many are.
These 1 mm-sized crystals were found precipitated in a couple of gallons of glaze containing 85% Ferro Frit 3195. They are hard and insoluble. Why and how to do they form? Many frits are slightly partially soluble and the degree to which they are are related to the length of time the glaze is in
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Context: Ferro Frit 3195, A glaze slurry precipitates at flakes, Precipitate can forms in firtted glazes, remember to screen it, Precipitated crystals from a glaze having 60% lead bisilicate frit, G2925B glaze can precipitate crystals like this over time, Precipitation Wednesday 26th October 2016 |
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