Selecting the right mesh is crucial; choosing the appropriate mesh and screen system based on specific printing requirements is key to enhancing print quality. Factors such as tension, thickness, and color must be considered during selection. Generally, mesh tension should exceed 15–20 N/cm; thinner mesh yields better resolution, while the mesh opening determines the ink volume. Advances in modern technology have enabled the use of high-tension and finer meshes, thereby improving print quality.
When preparing the screen, the mesh should be cleaned first to minimize pinholes and "fish-eyes" during coating. New or reused screens require degreasing. When using direct film systems, a special mesh-abrading paste is needed to enhance the bond between the film and the mesh. After degreasing, a wetting agent is used to improve the adhesion of capillary film to the mesh.
There are four basic methods for applying capillary film, each with slightly different operational steps. Using the correct type and thickness of capillary film ensures high-quality screens. If the film is too thin, jagged edges or "saw-toothing" may occur; adhering to guidelines regarding film thickness and mesh count helps prevent these issues.
Application techniques for direct emulsion include coating methods such as "wet-on-wet" and "wet-on-dry." The wet-on-wet method is suitable for 90% of printing applications, whereas the wet-on-dry method is appropriate for meshes with counts exceeding 140 threads/cm. Coating quality is influenced by the process, and the amount of emulsion applied per pass depends on the design of the coating trough; uneven coating and pinholes are often linked to the trough's design.
Screen-making rules include the following: the width of the finest graphic elements should exceed the screen thickness; the emulsion thickness should be 20–25% greater than the mesh thickness (15–20% for fine lines); lower-viscosity emulsions require more coating passes; the emulsion layer should be at least 5 microns thicker than the mesh; and finer mesh threads result in higher resolution. In summary, producing high-quality screen printing stencils requires the careful consideration of various factors. Adhering to these guidelines is fundamental to achieving excellent print results. By selecting the appropriate mesh and stencil system and optimizing the production process, print quality can be significantly enhanced.