Wet laying is similar to paper production processes, and leaves the strands oriented in random directions. This leads to a similar strength across all direction of the fabric, but the random nature can lead to surface defects which may not be corrected through rolling.
The process involves a dilute slurry of water and fibers being deposited onto a moving wire screen. This is drained to form a web, which is further dewatered, pressed between rollers and then dried. Binding agents are often added at a later stage of the process to improve cohesion.
Fiberglass strands are among the most used components for wet laid applications. However, they do not disperse well in water, presenting challenges which can lead to poor uniformity and weak inter-fiber bonding. While process improvements can solve these issues, monitoring for defects is still very important.