Veegum, or VeeGum T (or VGT) is not a 'gum', rather it is a refined fine particle mineral called 'smectite' (bentonite and hectorite are members of the smectite group). It is a complex colloidal and extremely plastic and sticky magnesium aluminum silicate. It is an off-white insoluble flaky consistency and swells to many times its original volume when added to water. Its aqueous dispersions are thus high viscosity thixotropic gels at low solids. A potter encounters this phenomenon when employing significant percentages of VGT in glazes and porcelain bodies (e.g. more than 2%), finding that much more water is needed to produce a pourable suspension. Veegum is not subject to attack by microorganisms. Various grades are classified according to viscosity and ratio of aluminum to magnesium content.