|Monthly Tech-Tip |
Alternate Names: Hectalite
A plastic magnesium-rich sodium hectorite clay of microfine particles (it is a refined version of the same material from which HPM20 and Volclay bentonite are made). One gram of the material has a surface area greater than 750 sq. meters!
Hectalite is available in grades 200 and GM, they have the same chemistry and other physical data except:
-Hectalite 200 has a viscosity of 2000-5000 cps @ 5% solids whereas GM is 50 cps.
-GM has a slightly lower pH of 8-10 whereas 200 is 9-11.
Hectalite 200 is intended for rheology control (stabilizing, gelling, suspending and binding household products, aerosols, paints, enamels and ceramic slurries) whereas GM is intended for binding and plasticizing in ceramic bodies.
The high MgO, CaO and low Al2O3 give this material a chemistry that is unlike other typical fine particled clays.
Brightness: 70 minimum
Density: 2.6 g/cubic cm
Texture: Soft, slippery
Color: White to off-white
Wet Particle Size:
Through 200 mesh: 99.75%
Through 325 mesh: 99.0%
Moisture %, Maximum: 12%
pH (2% slurry): 9.0-11.0
Specific to GM:
Free Swell: Minimum 24 mls
Viscosity: 2000 - 5000 @ 5% solids
pH: 8.0-10.0 @ 2% solids
CAS No. 1302-78-9
A comparison of the plasticity of Volclay 325 Bentonite:Silica 25:75 (top) and Hectalite 200:Silica 50:50. Both are mixed with silica powder. The latter (a highly refined bentonite) is much less plastic even though it is double the percentage in the recipe.
Hectalite 200 data sheet
Clays that are not kaolins, ball clays or bentonites. For example, stoneware clays are mixtures of all of the above plus quartz, feldspar, mica and other minerals. There are also many clays that have high plasticity like bentonite but are much different mineralogically.