Monthly Tech-Tip from Tony Hansen SignUp

No tracking! No ads!

1-9 | A | B | C | D | E | F | Frits | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z

Mahavir Potash Feldspar

Alternate Names: PF-01 Potassium Feldspar, PF-01 Potash Feldspar, Mahavir Feldspar

Oxide Analysis Formula
MgO 0.15% 0.02
Fe2O3 0.08% -
CaO 0.15% 0.02
Na2O 3.00% 0.27
K2O 11.50% 0.69
Al2O3 17.50% 0.97
SiO2 67.00% 6.30
LOI 0.50%n/a
Oxide Weight 561.90
Formula Weight 564.73


This feldspar is being imported by Laguna Clay into North America (from India). It will be marketed as the successor to G-200 feldspar and its temporary substitute, the MFEL S3470 blend (Minspar/G-200HP blend). The chemistry of this is very similar to G-200 (this has a little more K2O, a little less Al2O3 and a little more SiO2).

The manufacturers data sheet describes it as a selected white firing high grade potassium feldspar typically used in frits, ceramic glazes, sanitary ware, table ware, white glass, TV tubes etc. The data sheet calls it PF-01 Potassium Feldspar so there is some confusion about what it will be called.

The analysis supplied here has been rationalized from that supplied on the manfacturers data sheet. It specifies plus or minus values for oxides as follows:
SiO2 +/- 1%
Al2O3 +/- 0.5%
K2O +/- 1%
Na2O +/- 0.5%
CaO < 0.3%
Fe2O3 +/- 0.02%
MgO < 0.3%
TiO2 < 0.01%
LOI 1% max

Mineralogy: 65-75% Microcline
21-30% Albite
0.6% Anorthite
1% Kaolinite
10-15% Quartz

Melting temperature: 1220C (soaking time 30 minutes)
Particle size: 2% +63 microns (the data sheet lists others but this is the one being imported by Laguna Clay)

Related Information

Another new substitute for G-200 feldspar in North America will be importing this material from India. It will be called Mahavir Potash Feldspar. You can find it in the reference materials in your account. You might like to leave recipes as is (naming G-200 as the material) but insert "Mahavir Potash Feldspar" as the lookup so the chemistry will be correct.

Original container bag of Mahavir Feldspar

A nylon fabric bag with no safety markings.

Which common American/Canadian feldspars can substitute for each other?

Feldspars melting

Feldspars are employed in glaze recipes as melters. So comparing their melt fluidities should be helpful in deciding if one can substitute for another (of course, if possible a soda predominant feldspar should be substituted for another soda spar). Feldspars don't melt alone at cone 6 (2200F) so we mixed each with 15% Ferro Frit 3195. Nepheline Syenite is obviously the champion melter here. Other similar ones can be spotted easily. In the end, degree of melt is a valid consideration in determining if one feldspar is a viable substitute for another in a recipe. Even if the feldspar you want to substitute does not melt as much a little frit can be added to the recipe to make up for the difference (e.g. even just 1 or 2%).


Materials Potash Feldspar
Materials Custer Feldspar
The most common potash feldspar used in ceramics in North America. While having been a standard for many decades its supply appears in doubt in 2024.
Materials G-200 Feldspar
Materials G200 Old Blend Feldspar
Materials Fortispar
Materials G-200 EU Feldspar
Typecodes Feldspar
The most common source of fluxes for high and medium temperature glazes and bodies.
Mahavir PF01 Feldspar Data Sheet
By Tony Hansen
Follow me on

Got a Question?

Buy me a coffee and we can talk, All Rights Reserved
Privacy Policy