Abstract: A method is disclosed for the manufacture of screen cylinders, e.g. for removal of debris such as sand, rock, metal, resin etc. from a liquid suspension used in the pulp and paper industry. The screen is of the type having a plurality of slot passages, each extending axially the entire axial length of the cylinder. According to the invention, the width of the slots is controlled by determining the physical structure of the screen, particularly the overall thickness of the screen and the backing reinforcement ribs, prior to the rolling of the screen plate into a cylinder. A table of a number of different sizes is included showing the practical range of application of the invention. The invention allows the use of standard cutters used in the milling of the slots for the production of screens with much narrower slots to obtain an improved degree of removal of contaminants without having to use specially thin cutters. Screens produced by the method are also claimed.