An improved nozzle of the type which directs a flow of fluid against a moving substrate to obtain a uniform surface coating on the substrate. The nozzle consists of two rigid body halves mounted on a fluid feed pipe. One body half is fixed, and the other body half is rotatably mounted on the feed pipe for adjusting the size of the nozzle discharge opening. One or more closure loading assemblies are mounted on the nozzle for adjusting the size of the discharge opening and for maintaining the nozzle opening in an adjusted position. Each closure loading assembly has a fluid-actuated cylinder which forces the body halves toward a closed position opposing the internal fluid pressure in the nozzle body in combination with an adjustable differential screw. The adjustable screw is mounted on one of the body halves and engages a stop on the other body half to set the size of the nozzle discharge opening. The closure-loading assemblies will maintain the adjusted nozzle opening even after opening and closing of the nozzle for cleaning and will permit adjustment of the discharge opening during operation of the nozzle. The feed pipe is connected to a source of fluid and distributes the coating control fluid throughout the length of the nozzle through a plurality of spaced holes formed in the feed pipe and nozzle body halves. Each closure loading assembly and stop screw effectively acts in a common plane perpendicular to the transversely extending fluid feed pipe.