In coating applications, an air knife is a device that uses compressed air to blow a thin, uniform layer of liquid or powder coating material onto a surface. The air knife is typically made of a thin, flat blade that is mounted on a compressed air source, and the coating material is introduced into the airstream to create a controlled flow. As the material is blown onto the surface, the air knife helps to distribute it evenly, producing a uniform coating thickness. Air knife coating is often used in industrial settings to coat materials such as paper, plastics, and metals, and is valued for its precision, efficiency, and consistency.