Interacting glazes at a vertical interface
Glazes interacting at a vertical interface.
The matrix (i.e. background) glaze and inlay glaze do not overlap before
firing.
The matrix glaze is a saturated iron micro-crystalline matte glaze high in
phosphorus and calcium.
Several closeups of the interaction region of the two glazes are shown and,
for context,
Additionally, for ammusement value, a close-up picture of a micro-crystalline
matte glaze,
With sufficient time, the inlay glaze and matrix glaze would merge into the
same glaze that would have resulted
The matrix glaze is satIron_mashiko_neph_Imerys, the inlay 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,
150 deg F an hour to 250 deg F
400 deg F an hour to 1800 deg F
200 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
300 deg F an hour to 1750 deg F then a 50 minute 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
K2O 0.08
Al2O3 0.61
SiO2 4.03
molecular percent Silica 66.7%
K2O 0.11
Al2O3 0.56
SiO2 3.12
molecular percent Silica 63%
K2O 0.11
Al2O3 0.59
SiO2 3.43
molecular percent Silica 65.2%
The original inlay, as placed in the kiln, was a simple curve, about 3/8th of
an inch thick.
The primary difference between the matrix and inlay glazes is in the lower
alkali metals and higher CaO
Note - the close-ups have been 'enhanced' to make detail visible.
The inlay glaze is a saturated iron aventurine glaze
high in alkali metals.
a picture of the pot.
jingdezhen-iron-6-19, which is similar in composition
to that of the glaze at the midpoint of a
line blend between the
matrix glaze and inlay glaze.
glaze
Alumina
Silica
Silica:Alumina ratio
ratio Alkali metals:Alkaline earths
Fe2O3
jingdezhen-iron-6-9
0.59
3.4
5.8
1.8
0.2
midpoint glaze of matrix glaze and inlay glaze
0.58
3.5
6.1
1.9
0.27
from firing a mixture of the two raw
glazes. Comparing the average of the two glazes to a known glaze with
similar empirical formula gives some estimate of the appearance of the
interaction zone.
the mask is removed, and the open area filled in with a
second glaze, using a bulb syringe
with a needle applicator.
Close up Images of the interaction region
Image of the glaze jingdezhen-iron-6-19
Image of the piece
Bowl with glaze satIron_mashiko_Imerys and inlay glaze
iron_8_R_C10_13PSi.
bowl is 8 inches in diameter
oxidation firing to cone 10 in an electric kiln
Firing profiles
Up Fire profile
Down Fire Profile
Clay body is a grolleg porcelain from Tacoma Clay Art Center.
glaze compositions
Matrix Glaze
satIron_mashiko_neph_Imerys:
Na2O 0.11
Li2O 0.28
CaO 0.51
MgO 0.02
Fe2O3 0.25
P2O5 0.15
Inlay glaze
Empirical Formula iron_8_R_C10_13PSi :
Na2O 0.45
Li2O 0.25
CaO 0.17
MgO 0.02
Fe2O3 0.28
reference glaze compared to midpoint of inlay and matrix
jingdezhen-iron-6-19:
Na2O 0.37
Li2O 0.16
CaO 0.29
MgO 0.07
Fe2O3 0.20
P2O5 0.04
Remarks
Here the two glazes combine to form a new micro-crystalline
glaze which dominates the interaction zone.
of the matrix gaze. Interdiffusion between
these two glazes is sufficiently intense that the result is a nearly
homogeneous micro-crystalline glaze.