Saturated Iron Satin Matte Glaze

The glaze nepheline_Z1A_2 was seen with a bronze colored satin matte texture. On further testing, depending on placement in
the kiln and glaze application thickness, it varied from an oil spot to a full gloss.

In the pursuit of a reliable version of this brushed metallic bronze glaze, I tested four neighbor glazes.

nepheline_Z1A_1E_0 some CaO -> MgO

nepheline_Z1A_1E_1 Li2O -> K2O

nepheline_Z1A_1E_2 less SiO2, some Na2O -> K2O + MgO

nepheline_Z1A_1E_3 some Na2O -> K2O, increase Al2O3.

cone 10 oxidation

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

The cones show this as a cone 10 firing.

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

glaze compositions

Empirical Formula glaze nepheline_Z1A_2 :

K2O        .04
Na2O        .67
Li2O        .06
CaO        .06
MgO        .17

Al2O3        .73
Fe2O3        .23

SiO2        4.06

molecular percent Silica 67%

Empirical Formula glaze nepheline_Z1A_1E_0 :

K2O        .04
Na2O        .67
Li2O        .06
CaO        .01
MgO        .22

Al2O3        .73
B2O3        .23

SiO2        4.03

molecular percent Silica 67%

Empirical Formula glaze nepheline_Z1A_1E_1 :

K2O        .1
Na2O        .68
CaO        .06
MgO        .16

Al2O3        .73
Fe2O3        .25

SiO2        4.1

molecular percent Silica 67%

Empirical Formula glaze nepheline_Z1A_1E_2 :

K2O        .16
Na2O        .51
Li2O        .06
CaO        .05
MgO        .22

Al2O3        .74
Fe2O3        .23

SiO2        3.5

molecular percent Silica 64%

Empirical Formula glaze nepheline_Z1A_1E_3 :

K2O        .16
Na2O        .57
Li2O        .06
CaO        .04
MgO        .17

Al2O3        .77
Fe2O3        .22

SiO2        4

molecular percent Silica 67%

The glaze: nepheline_Z1A_2, Left Satin, Right gloss

The glaze whose neighbors I explore. I am looking for a reproducible version of the satin matte incarnation of this glaze, seen on the left.

There is a contrast glaze decoration in the gloss version, on the right. The reflection of this decoration is seen to the right on the pot wall,
showing its high refectivity on this pot.

The neighbor glazes

bowls are ~ 4 inches in diameter

glaze nepheline_Z1A_1E_0

glaze nepheline_Z1A_1E_1

glaze nepheline_Z1A_1E_2

glaze nepheline_Z1A_1E_3

Remarks

The changes in nepheline_Z1A_1E_0, and nepheline_Z1A_1E_1 are in the balance of bases, to less powerfull bases.

nepheline_Z1A_1E_2 has less silica in addition to a shift to less potent bases.

nepheline_Z1A_1E_3 has higher alumina in addition to a shift to less potent bases.

nepheline_Z1A_1E_1 is shown with a heavy glaze application yet retains some texture, and is not a full gloss glaze. In addition with a
thin application it is a viable glaze with the desired texture. It will need additional testing to verify this.

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