Architectural Coatings / Exterior / Feldspar


Feldspar (silicate, chemical formula Na(AlSi3O8), where Na can also be replaced by K) is one of the main constituents of the Earth’s crust. Feldspar can be characterised by:


  • Relatively high Mohs hardness of 6
  • Low electrical conductivity
  • Easy to wet
  • High inertness in various media.


And, depending on the grade:


  • Low content of lamellar mica (Unispar FF)
  • Low fine crystalline silica fraction (no labelling) (Unispar PG (W))
  • Whiteness (Unispar PG W).


Note when using feldspar: depending on the particle size distribution of certain products, they can be labelled STOT RE 2. For more detailed information, visit

Sibelco feldspar quarry in Cine (Turkey)


Basic properties

Property Value Unit
Moisture < 0.5 [%]
Hardness (Mohs) 6 (6.5) [-]
Refractive index 1.53 [-]
L.O.I. 0.5 [%]
Density 2.6 [kg/ dm3]



Product overview

Product Grade D50





[g/ 100 g]

pH L*
Unispar FF-20 6 n.d. 32 9.8
FF-30 8 n.d. 28 9.7
FF-60 19 n.d. 27 9.5
FF-150 23 n.d. 24 9.4
PG4 4 17 26 9.5 94.5
PG W7 7 25 27 8.0 97.0
PG W13 13 60 22 8.1 96.4
PG W20 20 80 19 8.2 96.2

Production locations Unispar



Feldspar will provide:


  • Ease of tinting: due to the combination of refractive index, brightness and color, paints including feldspar will give excellent reproducible colour results when working with tinting systems.
  • Texture effect: usage of coarse feldspar grades will ensure texture to the surface of the coating.
  • Tint retention: paints including cristobalite show improved tint retention over other minerals when subjected to natural weathering.
  • UV resistance and weatherability: due to its inertness, feldspar supports good UV and weatherability performance to exterior architectural coatings.

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