Publisher Summary This chapter discusses several aspects of the coating process and aims to provide a broad understanding of the various coating applicators that are used. A typical coated structure is a flexible substrate with functional layers coated on either side or on both sides. The substrate can be a single polymer, such as polyethylene (PE), biaxially oriented polypropylene (BOPP), polyethylene terephthalate (PET), or polyvinyl chloride (PVC). There can be a single coated layer or multiple layers depending on the product requirements. The layers may function as oxygen, light or moisture barriers, or may function as release layers to which adhesives do not stick. In addition, adhesives are often coated to form laminated structures and conductive antistatic layers are coated to prevent charge buildup. The web transport system conveys the uncoated substrate from the unwind stand through the coating station and the dryer to the rewind stand, while maintaining the appropriate speed and tension control. The coating solution is applied to the moving web with a coating applicator. The coating station holds the coating applicator in a fixed position and permits the operator to set precisely and accurately the coating parameters such as gaps and roll speeds. The coating line may also contain a section between the unwind and the coating applicator to surface treat the substrate before it is coated.