Interactions between Abutting Glazes

cone 10 oxidation

Firing profile

Up Fire profile

150 deg F an hour to 250 deg F

400 deg F an hour to 2050 deg F

120 deg F an hour to 2250 deg F

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

Down Fire Profile

A half hour hold at 1750 deg F

A three hour hold at 1700 deg F

slow downfire at 25 deg F an hour in the interval 1700 deg F to 1650 deg F

A one hour hold at 1650 deg F

The cones show this as a cone 10 firing.

After glaze application, two glazes are side by side, no gap between, neither overlaping.

The two glazes may react with each other and merge, developing textures and colors seen in neither.

Alternatively, they might retain their individual identities. leaving a sharp demarcation between.

inlay glaze is paperWhite_ZK_2 - different background glaze

Here is paperWhite_ZK_2 used as the inlay design in the two glazes paperWhite_ZP_Q_1M_EU, and in hanksSatin_ZV_0.
In the first glaze, paperWhite_ZP_Q_1M_EU, the boundary is a diffuse fuzzy edge slightly colored and broadened a bit,
one glaze ends, the other begins.

By contrast, in the glaze hanksSatin_ZV_0, the interfacial region dominates the design and is nearly as large as the uncontaminated region
of the inlay itself, paperWhite_ZK_2.

background glaze is hanksSatin_ZV_0 different inlay glaze

Here is hanksSatin_ZV_0 with the two glazes paperWhite_ZK_2 + .1 % chrome, and sh_ZJ_2PAlSi used as inlay design.
As noted, paperWhite_ZK_2 + .1 % Chrome produced a large fanciful multicolored interaction region.
sh_ZJ_2PSiAl reacted only to the extent of producing a thin sharp high contrast golden brown line between the two glazes.

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

glaze composition of the background glazes

Emperical Formula hanksSatin_ZV_0:

K2O        0.12
Na2O        0.04
Li2O        0.00
CaO        0.48
MgO        0.02
BaO        0.34

Al2O3        .38

SiO2        2.56

molecular percent Silica 65 %

Emperical Formula paperWhite_ZP_Q_1M_EU:

K2O        0.22
Na2O        0.23
Li2O        0.0
CaO        0.08
MgO        0.11
BaO        0.19
SrO        0.17

Al2O3        .62

SiO2        3.69
TiO2        0.16

molecular percent Silica 63 %

Emperical Formula paperWhite_ZK_2 - inlay glaze:

K2O        0.21
Na2O        0.23
Li2O        0.05
CaO        0.20
MgO        0.01
SrO        0.30

Al2O3        .6

SiO2        3.02
TiO2        0.18

molecular percent Silica 63 %

glaze has .1 % Crome oxide added.

Emperical Formula sh_ZJ_2PAlSi inlay glaze:

K2O        0.08
Na2O        0.33
Li2O        0.5
CaO        0.05
MgO        0.04

Al2O3        1.4

SiO2        3.76

molecular percent Silica 61 %

glaze is contaminated with ~ .1 % redart clay

Each bowl is ~ 4.5 inch

glaze paperWhite_ZK_2 + .1 Crome with differing backgound glaze

Background Left paperWhite_ZP_Q_1M_EU and Right hanksSatin_ZV_0

glaze hanksSatin_ZV_0 with differing inlay decoration glaze

Inlay Left paperWhite_ZK_2 and Right sh_ZJ_2PAlSi

Full View of pots

full view

bowl glaze paperWhite_ZP_Q_1M and paperWhite_ZK_0 inlay

full view

bowl glaze hanks_Satin_ZV_0 and paperWhite_ZK_0 inlay

full view

bowl glaze hanks_Satin_ZV_0 and sh_ZJ_2PAlSi inlay

Remarks

Its not surprising that paperWhite_ZP_Q_1M_EU and paperWhite_ZK_2 don't exhibit an interactions,
they have similar compositions. I note that paperWhite_ZP_Q_1M_EU has half the CaO of paperWite_ZK_2, so Chrome could have
migrated across the boundary and shown a contrasting color.

Although hanksSatin_ZV_0 seems a very reactive glaze, sh_ZJ_2PAlSi is high in alumina, yet it is high in alkali metals as well,
the result wasn't a surprise, though a more complex boundary wouldn't have been a surprise either.

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