High Alumina Orange

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

I continue my investigating of low iron glazes with ever higher alumina.

These glazes have higher alumina and lithium than prior glazes, lower silica:alumina ratio and show a shift in color from pinkish orange to bright orange.

Alumina is greater than 1.5 and the silica:alumina ratio is between 2.3 and 3, iron concentration ~.03.

The indications are that higher alumina and lower silica produce brighter oranges in low concentration iron glazes.

These are high alkaline glazes, with total CaO plus MgO ~.06 the residual impurities in the feldspars and clays.

The names of these glazes reflect only that shino glazes are nearly unique in having such high alumina, making these glazes remote cousins of shino's.

The pots are small conical bowls ~3 inches in diameter.

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glaze shino_2016_03_31_2C

Of the three glazes, this first glaze, shino_2016_03_31_2C has alumina equal to 1.5, and the highest silica:Alumina ratio of 3.

This glaze is pinker than the others and glossier.

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glaze shino_2016_07_06_0

this second glaze, shino_2016_07_06_0 has alumina equal to 1.5 and silica:Alumina ratio of 2.4.

Where thin this glaze is bright orange.

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glaze sh_2016_08_0

this third glaze, shino_2016_08_0 has alumina equal 1.7 and the lowest silica:Alumina ratio of 2.3.

Another bright orange where thin glaze.

This glaze has the highest Lithia content of all three glazes.

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