The Effect on a Glaze of a trace of Chrome
I show here the effect of adding ~0.02% chrome oxide to five glazes.
Previously, I'd added 0.02% chrome oxide to a white matte glaze, to have it turn
translucent and grey.
I decided upon a quick and dirty investigation of the effect of chrome on
matte glazes. I added a
The glazes chosen were recently tested, and I used the remains from those
tests. The result is qualatative,
I divided 0.05g of chrome oxide into five segments, and added one segment
to ~50 g of each glaze.
With that small addition of chrome oxide each of these glaze is pitted.
Those pits range from slight pinholes
Each of these glazes had a greater range of colors with the addition of the
chrome oxide.
Each piece is a small bowl ~3.5 inches in diameter.
Preceding the image of the glaze with the addition of chrome oxide, is an
image of the glaze in its original form.
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 0.20
Al2O3 0.6
SiO2 3
molecular percent Silica 64.3%
0.5% copper carbonate
0.5% Silicon Carbide for local reduction
K2O 0.16
Al2O3 0.5
SiO2 2.54
molecular percent Silica 62.2%
Added:
0.5% Silicon Carbide for local reduction
K2O 0.15
Al2O3 0.56
SiO2 2.64
molecular percent Silica 62%
Added:
0.3% Silicon Carbide added for local reduction
K2O 0.22
Al2O3 0.61
SiO2 2.88
molecular percent Silica 64%
Added:
0.5% Silicon Carbide added for local reduction
K2O 0.22
Al2O3 0.61
SiO2 2.86
molecular percent Silica 63.7%
Added:
0.5% Silicon Carbide added for local reduction
K2O 0.21
Al2O3 0.56
SiO2 2.77
molecular percent Silica 63.6%
Added:
0.5% Silicon Carbide added for local reduction
The change in color isn't surprising, because grey is
a possible chrome color, the change in texture was unexpected.
small bit of chrome oxide to each of five matte
glazes.
because measuring 0.02g is difficult, and the
quantity of glaze to which the chrome oxide was added is approximate.
to giant frothy unhealed bubbles.
Additionally each of these glazes is somewhat glossier.
Image of the pieces
bowl with glaze faux-tsabar-harris-yellow-Z2R
bowl with glaze faux-tsabar-harris-yellow-Z2R + 0.02% chrome oxide
bowl with glaze ru_P_tsabar_PMg
inside of bowl with glaze ru_P_tsabar_PMg + 0.02% chrome oxide
outside of bowl with glaze ru_P_tsabar_PMg + 0.02% chrome oxide
bowl with glaze ru_Z2Q
bowl with glaze ru_Z2Q + 0.02% chrome oxide
bowl with glaze tsabar-celadon-PAl-PMg-Z2Q
bowl with glaze tsabar-celadon-PAl-PMg-Z2Q + 0.02% chrome oxide
bowl with glaze tsabar-celadon-PAl-Z2Q
bowl with glaze tsabar-celadon-PAl-Z2Q + 0.02% chrome oxide
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 faux-tsabar-harris-yellow-Z2R :
Na2O 0.20
CaO 0.41
MgO 0.06
ZnO 0.13
Fe2O3 0.02
SnO2 0.05
Empirical Formula ru_P_tsabar_PMg :
Na2O 0.07
CaO 0.59
MgO 0.16
ZnO 0.02
Fe2O3 0.02
P2O5 0.01
Empirical Formula ru_Z2Q :
Na2O 0.08
CaO 0.51
MgO 0.26
Fe2O3 0.02
P2O5 0.02
Empirical Formula tsabar-celadon-PAl-PMg-Z2Q :
Na2O 0.07
CaO 0.54
MgO 0.11
ZnO 0.06
Fe2O3 0.01
Empirical Formula tsabar-celadon-PAl-Z2Q :
Na2O 0.06
CaO 0.64
MgO 0.02
ZnO 0.06
Fe2O3 0.01
Empirical Formula tsabar-harris-celedon-PAl :
Na2O 0.07
CaO 0.65
MgO 0.01
ZnO 0.06
Fe2O3 0.01