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 magnesium aluminum silicate. It is an off-white insoluble flakey 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; often a lot more water is needed to produced the desired viscosity. Veegum is not subject to attack by microorganisms. Various grades are classified according to viscosity and ratio of aluminum to magnesium content.

In glazes VGT is used as an in-mix suspending agent and surface hardener. It is also suitable for use as a spray-on surface hardener before decorating (mix it with water and put a light layer on dried ware).