Iron Red
Here is a glaze that is an iron red when thickly applied, but when thin,
becomes black with a dusting of coppery
In the region on the inside of the bowl near the lip, the thickness of the
glaze coating decreases rapidly and
The metallic particles only appear where the glaze thins and darkens. This is
seen in the close-ups taken
It is tempting to imagine that the iron crystals which give the glaze a red
color when thickly applied,
Pictures of the pot, and close-ups of the region near the rim, are shown.
bowl is ~ 4 inches in diameter.
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
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
K2O 0.09
Al2O3 0.57
SiO2 3.48
molecular percent Silica 66.2%
colored metallic particles. In this
example, the inside of the bowl has a thicker glaze application while the
outside is thinner.
there one can easily see the
transition of red to black with metallic particles.
near the rim which are shown below.
cluster into the coppery colored metallic
particles where the glaze is thin.
Image of the glaze iron_Alex_0PSi_MMg
inside
outside
Close up images near the inside upper rim
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
Empirical Formula iron_Alex_0PSi_MMg :
Na2O 0.45
Li2O 0.15
CaO 0.29
MgO 0.02
Fe2O3 0.17
P2O5 0.03