wirewater
The water used to wash the forming mesh conveyor belt (known as a wire).
wirewater: rinse spray that cleans the forming screen
Wirewater is the spray applied to the forming wire (or mesh screen) of a papermaking machine as it moves through its cycle. The wire carries wet fiber suspension across the forming section, and wirewater removes residual fiber, fines, and coating material from the screen surface before it returns to the fiber slurry tank. Without this cleaning, buildup accumulates on the underside of the mesh, causing uneven drainage, sheet defects, and eventual plugging.
The spray system is positioned at the tail end of the wire run, just before the screen loops back under the forming section. Wirewater is typically applied at moderate pressure, roughly 1 to 3 bar, and drawn from the machine's clear water supply or recirculated whitewater. The volume is modest compared to forming suspension flow, but adequate pressure ensures effective fiber removal from the mesh openings without damaging the screen fabric itself.
Wire wear and mesh choice
The abrasive action of wirewater, combined with mechanical flexing of the mesh as it passes around the drive rolls, gradually wears the wire. Coarser wirewater delivery or high-pressure jets accelerate this wear. Modern forming screens are engineered with synthetic monofilament construction, typically polyester or polypropylene, which resists both the spray environment and repeated flexing better than earlier wire mesh designs.
Wirewater quality matters operationally. If the supply contains suspended solids or scale, it deposits on the mesh and negates the cleaning benefit. On machines using recycled fiber or mechanical pulp, wirewater sometimes includes a biocide or chelating agent to prevent bacterial growth or mineral precipitation in the wet film on the wire.
The term wirewater is distinctly North American and most common in kraft and newsprint mills. European papermakers more often use the simpler phrase wire spray or screen wash. The word persists in older technical literature and among mill operators trained on machines installed before automated control systems replaced manual flow adjustment.