Wetting

Wetting refers to how a liquid interacts with a solid surface, specifically whether it spreads out or beads up. When a liquid "wets" a surface, it spreads smoothly, forming a thin, even film; if it doesn't, it beads into droplets. This behavior depends on the balance between adhesive forces (liquid-solid attraction) and cohesive forces (liquid-liquid attraction). Good wetting occurs when adhesive forces dominate, allowing the liquid to spread, which is important in processes like coating, painting, and cleaning. Conversely, poor wetting results in poor coverage and limited interaction between the liquid and surface.