Snow Flake at cone 6 and at cone 10 in an electric kiln
cone 6 Firing.
The kiln is cooled slowly, at a rate of 50 deg F an hour in the temperature interval 1850 to 1700.
It is then cooled 25 deg F an hour in the temperature interval 1700 deg F to 1650 deg F.
There is then a 1 hour hold at 1650 deg F.
cone 10 Firing
Firing 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 c/6 clay body is OH 6, the C/10 clay body is a grolleg porcelain
both from Tacoma Clay Art Center.
We last saw snow flake glazes:
These were intended to be Snow flakes glazes, which show white crystals on a
pale blue ground.
It seemed that with more heat work, these glazes might
do better, so we show the result of firing at cone 6 and cone 10.
The first two glazes hiAl_4Z_0 and hiAl_4Z_1 had a bluish ground at cone 6,
and a more intense blue ground at cone 10.
The other two glazes,
hiAl_4Z_2 and hiAl_4Z_3 were opaque white at cone 6, but have a blue ground
with many whitish crystals at cone 10.
There is a hint of luster
on the surface of the cone 10 glazes.
glaze compositions
These glazes have high alkali metals and titanium, and differ primarilyin the relative proportion of the alkaline earths.
the numbers in the Empirical or Seger Formula for the four glazes are respectively:
hiAl_4Z_0
Alkali metal .75
Li2O .14
CaO .12
MgO .13
Alumina .6
SiO2 3.2
TiO2 .22
hiAl_4Z_1
Alkali metal .75
Li2O .14
CaO .09
MgO .16
Alumina .6
SiO2 3.2
TiO2 .22
hiAl_4Z_2
Alkali metal .72
Li2O .14
CaO .15
MgO .12
Alumina .6
SiO2 3.2
TiO2 .22
hiAl_4Z_3
Alkali metal .75
Li2O .19
CaO .05
MgO .1
SrO .1
Alumina .6
SiO2 3.2
TiO2 .22
Each glaze is shown, first at cone 6 on a 5 inch diameter plate, then at cone 10 on a 3.5 inch test tile.
glaze hiAl_4Z_0
at cone 6 on a 5 inch diameter plate
at cone 10 on large test tile
glaze hiAl_4Z_1
at cone 6 on a 5 inch diameter plate
at cone 10 on a large test tile
glaze hiAl_4Z_2
at cone 6 on a 5 inch diameter plate
at cone 10 on a large test tile
glaze hiAl_4Z_3
at cone 6 on a 5 inch diameter plate
at cone 10 on a large test tile