Consequently, it is clear that producing colloidal particles from a bulk material requires work, e.g. we have to grind a bulk material up in order to produce a fine powder. So how can colloidal dispersions remain stable?
Why don't the colloidal particles spontaneously aggregate to form bulk material?
If a colloidal dispersion is stable, there must be an energy barrier to overcome in order to form the bulk phase; i.e. the system is metastable.