Changes in G200 Type Feldspar Information
Since 2009,
when the feldspar mine was depleted of the traditional G-200 potash feldspar,
the ceramics industry has been constantly adjusting.
In the last two years there have been more
significant changes. The Monticello,
GA (G-200HP) mine has closed and recently the Pacer Corporation has experienced
some challenging production issues.
Effective immediately, because of a broken ball mill, the Pacer
Corporation was forced to stop production of 200 mesh Custer feldspar.
The Pacer Corp. will now only produce 325
mesh Custer.
These
latest changes have not given the industry a lot of time to adjust, but
fortunately there is another potash feldspar available. G200EU is mined in Spain and has
proven to be a quality potash feldspar.
That being said, we cannot stress enough the importance of testing your
clay in your own studio situation. What works for one potter may not work for
all. There will undoubtedly be adjustments in certain situations.
Sheffield
Pottery has an inventory of clays made with 200 mesh Custer feldspar, but will
immediately start the transition to G200EU in our stock clay bodies. We will
also inventory 325 mesh Custer for those who would like to use it in custom
formulas and glazes.
Below is a side by side
comparison of the old and new available Feldspars.
|
|
Old G-200
|
G-200 HP
|
G-200HP Minspar Blend
|
Custer Feldspar
|
G-200 EU
|
|
SiO2
|
66.3
|
66.0
|
66.8
|
68.5
|
68.5
|
|
Al2O3
|
18.5
|
18.3
|
18.2
|
17.0
|
17.0
|
|
Fe2O3
|
.08
|
.09
|
.08
|
.10
|
.095
|
|
K2O
|
10.8
|
14.2
|
11.17
|
10.0
|
11.0
|
|
Na2O
|
3.1
|
.09
|
2.0
|
3.0
|
2.1
|
|
CaO
|
.80
|
.30
|
.66
|
.30
|
.05
|
|
MgO
|
trace
|
trace
|
trace
|
trace
|
.08
|
|
LOI
|
.15
|
.15
|
.20
|
.30
|
.05
|
Below is a list of our stock clay bodies affected by this change:
45R, 3350, 20231G, 20231NG, 20266,
92700, 95400G, 95400NG, 108200, 108300,
108950, 110100, S14, T1NS, T1S,
T3,T3S, T360, W1A