The Glaze Between

A three point Line Blend

Here are two glazes, both with silvery metallic crystals atop a variegated bottle brown, almost transparent base.

Though sharing the property of silvery surface crystals, these glazes have little else in common.
The first is a saturated iron glaze, higher in alkaline earths than alkali metals. The second, moderate in iron and
higher in alkali metals than in alkaline earths. To add to those differences, the first is substantially higher in silica
than the second, while the second contains phosphorus, not present in the first.

What is between these two extremes, I asked? Here is the result, the midpoint as it were, of the line blend with
those two glazes as ends.

No silvery surface crystals, though if thickly applied, it has an iridescent surface luster.

The design on the plate is created by adhering a mask and then applying the main glaze. After drying, the entire pot is
coated in wax, then the mask is removed and the open area filled in with a second glaze.

The Two end glazes

glaze mashiko_ZJ_0_NN

full view

Inside of bowl:

full view

Outside of bowl:

bowl is ~3 inches in diameter

glaze satIron_ZL_3

full view

plate is ~8 inches in diameter

The middle glaze

glaze mashiko_satIron_Z2Q

full view

Inside of bowl:

full view

Outside of bowl:

bowl is ~3 inches in diameter

oxidation firing to cone 10 in an electric kiln

Firing profiles

Up Fire profile

150 deg F an hour to 250 deg F

400 deg F an hour to 1800 deg F

300 deg F an hour to 2050 deg F

120 deg F an hour to 2310 deg F with a hold of 20 minutes at 2310 deg F

Down Fire Profile

300 deg F an hour to 1750 deg F then a half hour hold at 1750 deg F

300 deg F an hour to 1700 deg F then a Three hour hold at 1700 deg F

25 deg F an hour to 1650 deg F then a one hour hold at 1650 deg F

Clay body is a grolleg porcelain from Tacoma Clay Art Center.

glaze compositions

First glaze

Empirical Formula mashiko_ZJ_0_NN :

K2O        0.13
Na2O        0.11
Li2O        0.09
CaO        0.26
MgO        0.41

Al2O3        0.82
Fe2O3        0.22

SiO2        5.49

molecular percent Silica 73%

Second Glaze

Empirical Formula satIron_ZL_3 :

K2O        0.07
Na2O        0.44
Li2O        0.21
CaO        0.15
MgO        0.13

Al2O3        0.79
Fe2O3        0.10

SiO2        3.30
P2O5        0.05

molecular percent Silica 63%

Middle Glaze

Empirical Formula mashiko_satIron_Z2Q :

K2O        0.10
Na2O        0.30
Li2O        0.16
CaO        0.20
MgO        0.24

Al2O3        0.81
Fe2O3        0.17

SiO2        4.22
P2O5        0.04

molecular percent Silica 68%

Remarks

The middle glaze contains the brown tint seen in the two ends. In addition, however, there are hints of blue and
violet in the shadows. Additionally, its surface has a complex celular texture, as if composed of many translucent variegated layers.

The middle glaze is more nuanced, more complex than a simple glassy substrate with some metallic surface crystals.

The roll of glaze at its foot shows the middle glaze to be a viscous glaze, in contrast to the two ends,
both of which are rather fluid.

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