nickel purple

This is a further exploration of a firing which has a slow up-fire in addition to having the usual holds
on the way down.

A recent NCECA poster by Grace Dunham demonstrated the occurrence of malayaite, a tin silicate,
CaSnOSiO2, in a chrome tin pink glaze. It is claimed on Wikipedia that nickel in malayaite is a vibrant
purple.

Here is a glaze, oribe-woof-PAl-Ni-0, which contains nickel oxide and tin Oxide, and indeed is
purple, though not vibrant.

My past experience is that nickel in the presence of calcium is brown, so I replaced most of the
calcium of the original oribe glaze with barium.

There is an inlay on this bowl; it is irrelevant to the purpose of this note, however for completeness,
its creation is described below:

The matrix (i.e., background) glaze and inlay glaze overlap minimally before firing. The width of the
original inlay, varied from an eighth of an inch to three quarters of an inch.

The background glaze is oribe-woof-PAl-Ni-0; the inlay design is glazed with hiAlk_Z3P_MAl.

The design is created by adhering a mask and then applying the main glaze. After drying,
the mask is removed and the open area filled in with a second glaze, using a bulb syringe
with a needle applicator.

Image of the piece

full view

bowl with glaze oribe-woof-PAl-Ni-0 and inlay glaze hiAlk_Z3P_MAl

bowl is ~6 inches in diameter

oxidation firing to cone 10 in an electric kiln

Firing profiles

Up Fire profile cone 10

400 deg F an hour to 1800 deg F

300 deg F an hour to 2050 deg F

200 deg F an hour to 2220 deg F then a 90 min hold at 2220 deg F

120 deg F an hour to 2320 deg F

Down Fire Profile cone 10

300 deg F an hour to 1850 deg F then a 2 hr hold at 1850 deg F

300 deg F an hour to 1750 deg F then a 1 hr hold at 1750 deg F

300 deg F an hour to 1700 deg F then a 3 hr hold at 1700 deg F

25 deg F an hour to 1650 deg F then a 1 hr hold at 1650 deg F

Clay body is a grolleg porcelain from Clay Art Center in Tacoma, WA.

glaze composition

Empirical Formula oribe-woof-PAl-Ni-0 :

K2O        0.14
Na2O       0.04
CaO        0.13
MgO        0.01
BaO        0.68

Al2O3      0.35

SiO2       2.85
SnO2       0.10

molecular percent Silica 66%

Added:

1.5% Nickel Oxide

Inlay Glaze:

Empirical Formula hiAlk_Z3P_MAl:

K2O        0.12
Na2O       0.51
CaO        0.35
MgO        0.02

Al2O3      0.60

SiO2       3.28
P2O5       0.06
TiO2       0.22

molecular percent Silica 63.4%

Remarks

This firing features a 'rounded at the top' firing profile; with a hold of an hour and a half when it is 100 degreesF
below top temperature. The top temperature is 10 degrees hotter than my usual to compensate for no hold
at the top temperature. This is finally a rounded-at-the-top firing which gets as hot as my usual firing,
and gets the cones to the same state.

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