pale rutile blue
firing to cone 10 in oxidation
A half hour hold at 1850 deg F
slow downfire at 50 deg F an hour in the interval 1850 deg F to 1700 deg F
slow downfire at 25 deg F an hour in the interval 1700 deg F to 1650 deg F
One hour hold at 1650 deg F
pale rutile blue
The initial glaze alk_H90_L3_11_PMg_Z1, revered to is a nicely
varigated full gloss pale rutile blue glaze.
It has a mild orange peel
texture, and a few unhealed popped craters which are visible in the picture
below.
I show a migration in two steps from this glaze to a glaze without the
unhealed blisters.
This new glaze takes a nice leaf print as well, and is uncrazed.
However the orange peel texture remains.
We show below a close up of the initial glaze, alk_H90_L3_11_PMg_Z1.
The glaze alk_H90_L3_11_PMg_Z1
glaze composition
The initial glaze is high in alkali metals, with Al2O3 = .5, SiO2 = 3.5 and
alk:alumina ratio of 1.2.
First, Alumina is increased to .6, next silica is decreased to 3.1.
The Process
I began with by scoping the territory near the initial glaze, with increase
and decrease separately of each of Alumina, silica, Alumina and Silica, and
Alkali metals.
Uniquely among all these variations increased alumina eliminated the unhealed
popped blisterd without also eliminating the blue hue.
Any of the other mod's either eliminated the
color or didn't eliminate the sharp edged blisters.
The Path
step 1. initial glaze → alkTi_ZG_0 |
increase Alumina |
step 2. alkTi_ZG_0 → alkTi_ZG_H_0 |
decrease Silica |
The image on top is a closeup of the glaze alkTi_ZG_0, below, is a picture of a bowl with glaze alkTi_ZG_H_0.
the inside of the bowl has a leaf print.
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