A tea dust glaze
A glaze with discrete separated metallic micro-crystals.
150 deg F an hour to 250 deg F
400 deg F an hour to 2050 deg F
120 deg F an hour to 2250 deg F
60 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 0.27
Al2O3 0.61
SiO2 3.8
molecular percent Silica 67.7%
This tea dust glaze satIron_Z1D_G_3, has an alkali metal:alkaline earth ratio
of 0.82:0.18. The rather large and
In this case the crystals seen in satIron_Z1D_G_3 while larger, are
sparse. The higher alumina and
I expect that the discrete crystals are the result of balancing high alkali
metals with high alumina:
Bowl with glaze satIron_Z1D_G_3
inside
outside
bowl is ~ 5 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 composition
Empirical Formula satIron_Z1D_G_3 :
Na2O 0.27
Li2O 0.28
CaO 0.11
MgO 0.01
BaO 0.06
Fe2O3 0.21
Remarks
sparse crystals seen here are in
contrast with another of my glazes with a similar substantial
alkali
metal:alkaline earth ratio of 0.81:0.19. That glaze, iron_8_R_C10_13PSi, seen
as a background glaze
here ,
has slightly lower alumina, and a substantially lower
silica:alumina ratio. This lower alumina
and silica:alumina ratio allows the
dense, tiny sparkling micro-crystals characteristic of aventurine glazes
to form.
silica in satIron_Z1D_G_3 created a more
viscous, less fluid glaze, so that many fewer nuclei formed.
the alkali metals allow crystal nuclei (crystal
seeds) to form (also known as nucleation), but the alumina inhibits
their
formation, so that the few nuclei which do form can grow larger.