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 and inlay glazes are saturated iron glaze high in phosphorus.
The original inlay masks were thin continuous curves approximately three
eights of an inch thick.
The background glaze is significantly higher in alkali metals, lower in
calcium, iron and phosphorus.
Several closeups of the interaction region of the two glazes are shown, and
additionally for context,
The background glaze is iron_Alex_OPPSi_MMgFe, the inlay design is
glazed with
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 0.09
Al2O3 0.58
SiO2 4.16
molecular percent Silica 70.27%
K2O 0.08
Al2O3 0.61
SiO2 4.03
molecular percent Silica 66.7%
Added:
Cobalt Carbonate 1%
In the close-up pictures one notes regions of inlay entirely absorbed
by the interaction region.
Iron has diffused from the inlay glaze into the matrix glaze, and phosphorus
in the opposite direction.
Both the inlay and matrix glaze grow a variety of crystals, different for each
glaze. It appears that
The range of colors reflects the differing concentrations of both iron
and basic oxides (fluxes)
In parts of the design, the inlay glaze and
matrix glaze mixed in a manner that defies distinguishing
one
from the other.
Both glazes are fluid, so these two glazes mix
both via diffusion and gravitational effects.
a picture of the pot is shown.
satIron_mashiko_neph_Imerys.
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 piece
bowl with glaze iron_Alex_0PPSi_MMgFe and inlay glaze
satIron_mashiko_neph_Imerys
outside
bowl is ~6 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
Background glaze
Empirical Formula iron_Alex_0PPSi_MMgFe :
Na2O 0.45
Li2O 0.17
CaO 0.27
MgO 0.02
Fe2O3 0.11
P2O5 0.07
Inlay Glaze
Empirical Formula satIron_mashiko_neph_Imerys:
Na2O 0.11
Li2O 0.28
CaO 0.51
MgO 0.02
Fe2O3 0.25
P2O5 0.15
Copper Carbonate 0.5%
Remarks
there are crystals growing in the interface which are
seen in neither matrix, nor inlay glaze.
in the various phases present in the interface.