1. adj. [Drilling Fluids]

Referring to a finely divided, solid material, which when dispersed in a liquid medium scatters a light beam and does not settle by gravity; such particles are usually less than 2 microns in diameter. Some drilling fluid materials such as bentonite clay, starch particles and many polymers become colloidal when used in a mud. Oil muds contain colloidal emulsion droplets, organophilic clays and fatty-acid soap micelles.

See: alum,  clay-water interaction,  colloid,  colloidal solids,  micelle,  oil mud,  oil-mud emulsifier,  peptizing agent,  polymer,  prehydration