In seed oil production, the bleaching step removes pigment, oxidation products, and trace contaminants. Fullers clay is the most common material used, but some oils may use other components such as activated carbon, diatomaceous earth, trisyl (small glass beads), or rice hulls. The bleaching agent is mixed with the oil to create a slurry to generate an absorption cleansing process. Bleaching agents, like fresh bleaching clays, are fine powders which tend to be very dusty. Accurate measurement ensures an adequate supply of agent material available for oil finishing to prevent process disruption.