The effect of phosphorus

Firing profiles

Up Fire profile

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 2300 deg F with a hold of 20 minutes at 2300 deg F

Down Fire Profile

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

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

Empirical Formula glaze satIron_ZG_0 :

The glaze with Phosphorus

K2O        .1
Na2O        .49
Li2O        .19
CaO        .16
MgO        .06

Al2O3        .59
Fe2O3        .2

SiO2        3.14
P2O5        .04

molecular percent Silica 63%

Empirical Formula glaze satIron_ZG_0MPMG :

The glaze with No Phosphorus

K2O        .1
Na2O        .49
Li2O        .19
CaO        .16
MgO        .06

Al2O3        .59
Fe2O3        .2

SiO2        3.14

molecular percent Silica 63%

Glaze with Phosphorus

Glaze without phosphorus

Outside of bowl:

plate is ~6 inches in diameter, bowl is ~4 inches in diameter

Remarks

The glaze with phosphorus exhibits a fairly dense cover comprised of metallic gold micro-crystals where the glaze is thickly applied.
These surface clusters of metallic crystals are absent on the glaze that lacks phosphorus.

Although the non-phosphorus glaze exhibits micro-crystals on the surface, these are not the same crystals shown on
the phosphorus-containing glaze.

Note that without the phosphorus, the glaze is more fluid. Phosphorus is a glass former.

The leaf pattern on the first glaze is created by embedding a leaf in the wet glaze, waxing with an emulsion was when dry, then removing the leaf
and coating the exposed area with a thinned glaze or oxide wash.