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Mineral: Smectite


A highly plastic clay mineral related to montmorillonite (bentonite), more correctly, the name of the group on minerals that includes montmorillonite and other similar minerals.

The following was obtained from Southern Clay Minerals:
Smectite is a platy clay mineral. Three properties make smectite unique:

Shape - Smectite is a very lamellar material. Individual platelets resemble a business card in terms of morphology.

Size - Naturally occurring smectite ranges in size from 0.25 microns up to 0.75 microns across its broadest dimension.

Charge - Smectite platelets have a negative ionic charge within the body of the platelet and a positive charge on the edge of the platelet.

Due to its particular combination of properties, smectite can provide a host of benefits in water-based coatings. Due to its ability to structure in aqueous media, it is a thickener in low to mid shear ranges. Oftentimes it can be used to reduce or replace (in combination with other thickeners) cellulosic thickeners. It also prevents settling and syneresis (phase separation). Smectite will act as a pigment spacer (U.S. Patent 5,700,319) to improve hiding in titanium dioxide pigmented systems. Smectite improves sag resistance while not affecting flow and leveling to the extent other mineral thickeners might. This is due to smectite's true thixotropy which affords a delay in the recovery of viscosity when shear is released as opposed to the pseudoplastic tendencies of other minerals which cause an immediate recovery of viscosity.

Out Bound Links

In Bound Links

  • (Materials) B Clay - Buff Firing Stoneware Clay

    3B, PR#3 B

  • (Materials - Parent mineral) Laponite RD - Synthetic colloidal thixotropic clay
  • (Minerals) Hectorite

    An uncommon fine grained highly plastic clay mineral related to bentonite. Named after Hector, CA. From volcanic sources.

  • (Materials - Parent mineral) Veegum - Glaze Hardener, Binder

    Veegum T, Veegum CER, Veegum Pro, VGT

  • (Glossary) Porcelain

    Traditional utilitarian porcelains are comparatively white burning and vitreous clay bodies that are made from feldspar, clay and quartz. When fired, the feldspar flows and dissolves many of the other particles into a viscous glassy melt that bonds the quartz particles and, and if temperatures are s...

By Tony Hansen

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