URL: 

fluid-loss control

1. n. [Drilling Fluids]
The act or means of controlling (usually lowering) the volume of filtrate that passes through a filter medium. Control of fluid loss for a mud is achieved by several means, one of which is by addition of fluid-loss-control materials to the mud system. Another is to change the mud chemistry to make the materials already present work better. Adding a clay deflocculant to freshwater mud typically improves fluid-loss control.