saturated iron at cone 10
firing to cone 10 in oxidation
slow downfire at 50 deg F an hour in the interval 1850 deg F to 1700 deg F
slow downfire at 25 deg F an hour in the interval 1700 deg F to 1650 deg F
One hour hold at 1650 deg F
Our target glaze
Our target glaze, the starting point for the cone 10 glazes discussed here, is a cone 6 glaze which is covered in golden crystals. I'd like to reproduce those golden crystals at cone 10,
in a less temperamental glaze. The cone 6 glaze requires tight control on firing conditions and glaze application. I have several dozen glazes which give the magic
"covered in golden crystals" look at cone 6, all of which are similarly delicate. I thought increasing alumina might temper the abruptness of the transition
to the liquid like water state at which no glaze is viable. As increasing alumina likely increases the maturing temperature, I decided to modify this glaze to mature at cone 10.
I thought the cone 10 version would have different defects, which one can hope will give insight into the structure and properties of this glaze.
The three variations of the original cone 6 glaze have higher alumina and silica, with nearly equal silica:alumina ratio.
They differ from the original and each other by small perturbations in their bases. The result of this experiment was three cone 10 glazes, none of which have any golden crystals.
It is interesting to observe the result of higher magnificataion, as seen in the close up shown to the right of each glaze.
These seemingly distinct glazes are seen to have nearly the same phases/colores/textures.
The variation is in the sizes, relative proportions and arrangements of the various phases within the glaze.
The target glaze iron_8_R_157_0
glaze iron_8_R_157_0Z_0
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This glaze has higher lithia than original.
glaze iron_8_R_157_0Z_1
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This glaze has higher alkali metals and lower Magnesia than original.
glaze iron_8_R_157_0Z_2
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This glaze has lower silica:alumina ratio than the original.