Migrating abutting glazes

The interface of adjacent glazes.

Several closeups of the interaction region of the two glazes are shown and, for context, a picture of the pot.

The background glaze is hiCa-chrome-Z2O-half-M; the foreground design is glazed with iron_8_R_C10_13PSi.

The design 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.



Close up Images of the interaction region

full view

full view

full view

full view



Image of the piece

full view

bowl with glaze glaze hiCa-chrome-Z2O-half-M and inlay iron_8_R_C10_13PSi

bowl is ~7 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

Background glaze

Empirical Formula hiCa-chrome-Z2O-half-M :

K2O        0.05
Na2O        0.15
CaO        0.78
MgO        0.02

Al2O3        0.41

SiO2        2.58
SnO2        0.13

molecular percent Silica 62%

Added:

0.2% Chrome oxide

This is a chrome pink glaze



Inlay Glaze

Empirical Formula iron_8_R_C10_13PSi :

K2O        0.11
Na2O        0.45
Li2O        0.25
CaO        0.17
MgO        0.02

Al2O3        0.56
Fe2O3        0.28

SiO2        3.12

molecular percent Silica 63%



Remarks

The inlay glaze is higher in alkaline metals, silica and alumina, while background glaze is high in CaO.
Both these glazes are exceedingly fluid.

The mask for the inlay is a spiral, almost the entire area within the outer spiral is a mix of
inlay glaze and matrix glaze.

There are several different crystals growing in the interfacial region.

The first of the interface images has been heavily edited in an attempt to increase the visibility
of the radial lines in the orangey crystals near the upper left corner.

I see those mustard yellow crystals growing in the interface of iron_8_R_C10_13PSi and almost any other glaze.
I've no idea what those crystals are, would love to have a glaze of that color.

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