This coater applies coating material on the paper or paperboard with a certain thickness. With this machine, coating operation is very easy. The rubber tube is inflated uniformly with compressed air, and the blade (doctor) is pressed onto a backup roll around which the sheet receiving coating material is wound. In this status, coating is made by turning the handle. With a relief valve on the side of the machine, air pressure can be regulated appropriately reading the pressure gauge to secure the desired amount of coating material.