Phosphorus
What is the effect of phosphorus on the occurance of metallic micro crystals?
The Initial Glaze
With a small amount of phosphorus has an abundance of metallic micro crystals.
Without the
Excess phosphorus equally eliminates the metallic micro crystals.
The Glaze
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
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
K2O .25
Al2O3 .52
SiO2 3.2
molecular percent Silica 64%
K2O .16
Al2O3 .52
SiO2 3.18
molecular percent Silica 63%
It would seem these metallic micro crystals require phosphorus, but in small
quantities only. Too much phosphorus inhibits their growth.
The glaze satIron_ZG_1O_1Q_4 differs also in the balance of K2O and Na2O, but I do
not consider that relevant to the loss of the metallic micro crystals.
satIron_ZG_1O_0
satIron_ZG_1O_1Q_4
is essentially the initial glaze with a large addition of phosphorus,
The metallic micro crystals have almost vanished.
bowl are ~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
Initial glaze
Empirical Formula satIron_ZG_1O_0 :
Na2O .24
Li2O .24
CaO .17
MgO .1
Fe2O3 .21
P2O5 .05
Glaze with greatly increased phosphorus
Empirical Formula glaze satIron_ZG_1O_1Q_4 :
Na2O .32
Li2O .26
CaO .16
MgO .1
Fe2O3 .21
P2O5 .13
Remarks
What is the
optimal concentration of phosphorus? These crystals occur in a variety of
different glazes.
Does the required phosphorus concentration vary by glaze?