A wetting agent, also known as a surface active agent or surfactant, is a chemical substance that reduces the surface tension between two different phases, typically a liquid and a solid or another liquid. This reduction in surface tension allows for better wetting of surfaces by the liquid, improving the spreading and penetration of the liquid.

Wetting agents are commonly used in various industries including agriculture (to enhance the effectiveness of pesticides and fertilizers), textiles (for printing and dyeing processes), cleaning products (to improve the cleaning action), and in manufacturing processes to ensure proper mixing and dispersion of materials. They are also crucial in oil recovery processes where they help in dissolving and removing oil from rock surfaces.

The effectiveness of wetting agents lies in their ability to lower the interfacial tension, enabling substances like water to spread more easily across surfaces or penetrate into materials that would otherwise be resistant to wetting. This property makes them indispensable in many industrial applications aimed at enhancing the efficiency of chemical reactions, cleaning processes, and material handling.