A method including: sonicating a stream containing a dispersion comprised of agglomerated primary particles; and filtering the resulting sonicated stream containing a dispersion comprised of de-agglomerated primary particles. An apparatus including: an ultrasonic adapter to ultrasonicate a stream of a liquid dispersion of agglomerated primary particles; and a filter member adapted to filter the resulting ultrasonicated stream containing a dispersion of de-agglomerated primary particles; and optionally a coater adapted to coat the resulting filtered stream containing a dispersion of de-agglomerated primary particles onto a receiver.