Filler (also called grist) is a petroleum- or coal-based @[email protected] fraction of a green, @[email protected] or formulation. Coarse particles, \(>0.425\ \mathrm{mm}\), are sometimes referred to as tailings; fine particles, \(<0.074\ \mathrm{mm}\), are referred to as flour. @[email protected] flour is also used as a filler.