Copper Colors
If thin, this glaze is a variegated golden yellow brown micro-crystalline
matte, else if thick, a textured glossy grey green with an underlying red layer
peeking through.
This is David Tsabar's cone 9 waxy matte
copper red glaze, without the Tin Oxide, fired to a hot cone 10.
It is the tile in the upper left corner of the biaxial test.
inside of bowl:
Outside of bowl:
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
This glaze has 0.5% Copper Carbonate and 0.5% silicon carbide added
K2O 0.21
Al2O3 0.51
SiO2 2.88
molecular percent Silica 65.1%
Not the intended, yet an interesting glaze, both the color and texture.
Is the color the result of reoxidation of the colloidal copper, i.e. cuprous
oxide?
Would this glaze be red with the inclusion of Tin Oxide?
It is not an iron yellow. The quantity of iron in this glaze is insufficient
to produce such a strong color.
tsabar-harris-red
bowl is ~3 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 compositions
Empirical Formula glaze tsabar-harris-red :
Na2O 0.07
CaO 0.65
MgO 0.01
ZnO 0.06
Fe2O3 0.02
Remarks