Copper Red Electric Firing

I show the effect of two firing profiles on local reduction copper red glazes. These glazes contain 1000 mesh silicon carbide
as a local reducing agent.

cone 10 oxidation

The Firing profiles

Slow Firing Profile

Up Fire profile

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

Down Fire 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

Fast Firing Profile

150 deg F an hour to 250 deg F

400 deg F an hour to 2060 deg F

200 deg F an hour to 2310 deg F with a hold of 20 minutes at 2310 deg F

Down Fire Profile

A one hour hold at 1700 deg F

A two hour hold at 1600 deg F

The cones show both firings as cone 10 firing.

Clay body is a grolleg porcelain from Tacoma Clay Art Center.

glaze compositions

Empirical Formula glaze kangxi-cu-red-Z1D-1 :

K2O        .15
Na2O        .25
CaO        .53
MgO        .02
ZnO        .05

Al2O3        .39
B2O3        .1

SiO2        4.3
SnO2        .03

molecular percent Silica 74%

add:

Copper Carbonate 1%
Silicon Carbide 1%

Empirical Formula glaze kangxi-cu-red-Z1E-1 :

K2O        .08
Na2O        .16
CaO        .71
MgO        .01
ZnO        .04

Al2O3        .40

SiO2        3.6
SnO2        .05

molecular percent Silica 71%

add:

Copper Carbonate 1%
Silicon Carbide 1%

Empirical Formula glaze kangxi-cu-red-Z1E-2 :

K2O        .13
Na2O        .21
CaO        .6
MgO        .01
ZnO        .05

Al2O3        .4

SiO2        4.1
SnO2        .05

molecular percent Silica 74%

add:

Copper Carbonate 1%
Silicon Carbide 1%

Empirical Formula of glaze CopperRed-Electric From Robert Harris :

K2O        .07
Na2O        .22
CaO        .31
MgO        .13
SrO        .2
ZnO        .08

Al2O3        .39

SiO2        3.2

molecular percent Silica 70 %

add:

Copper Carbonate .5 %
Silicon Carbide .5 %
Tin Oxide 1 %

glaze kangxi-cu-red-Z1D-1

full view

slow firing

bowl is ~ 4 inches in diameter

full view

fast firing

bowl is ~ 8 inches in diameter

glaze kangxi-cu-red-Z1E-1

full view

slow firing

bowl is ~ 4 inches in diameter

full view

fast firing

bowl is ~ 6 inches in diameter

glaze kangxi-cu-red-Z1E-2

full view

slow firing

bowl is ~ 4 inches in diameter

full view

fast firing

plate is ~ 10 inches in diameter

glaze cooperRed-Electric

full view

slow firing

bowl is ~ 4 inches in diameter

full view

fast firing

bowl is ~ 6 inches in diameter

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