Drainage aids

1. Fiber development is the primary way to improve strength, but this leads to fines generation and greater water holding capacity which impede drainage
— use polymers to improve drainage through fines agglomeration or fines deposition onto the fiber surfaces.
2. Drainage process should be controlled, gradual and uniform.
— drainage and/or retention aids can help prevent sheet sealing.
3. Poor drainage may be the root cause of poor formation, two-sidedness, streaks, and deckle problems on the fourdrinier.
— on twin-wire formers, poor drainage may be leading cause of crushing.
See Retention.