Prewet

Prewet, or prewetting, refers to the practice of bringing a dry material into contact with a small amount of liquid before the main processing step. The goal is to improve wetting, dispersion, flow, adhesion, or handling in subsequent operations. The term is used across several industries and scientific fields, often with context-specific liquids and additives.

Common applications include dust suppression, powder handling, and coating processes. In dust control, surfaces or powders are lightly wetted with water or a surfactant solution to reduce airborne particles. In powder processing and tablet or coating production, prewetting can enhance flowability, reduce segregation, and improve uniform coating or granulation. In filtration and adsorption, prewetting hydrophobic media with an appropriate liquid promotes better contact with targets and more consistent performance.

In soil science and agriculture, prewetting of dry soils with water and wetting agents can improve infiltration, reduce crust formation, and promote more uniform moisture distribution. Prewetting is also used in pharmaceutical and food manufacturing to prepare powders for mixing, compaction, or encapsulation, minimizing agglomeration and improving process stability.

Safety and quality considerations are important: prewetting can alter chemical stability, microbial growth, or corrosion potential, and over-wetting can cause clumping or process interruptions. Selection of the wetting liquid, additives, and the degree of wetting are guided by material properties and the intended downstream process.

See also wetting agents, surfactants, moisture content, and capillary action.