Choosing the right frame and mesh is critical to achieving quality prints. This overview looks at different frame types, mesh parameters and performance criteria, screen-preparation tips, and recommendations for ensuring long-lasting screens.
Retensionable screens replace the need for a screen stretching device, which is usually only found in larger shops or as a service from suppliers. It allows a screen that has lost tension after initial use to be re-tensioned, and it gives the individual printer or shop the ability to create a new, tensioned screen in minutes. This is especially useful in production situations and economical once the frame is paid for.
Specially woven screen-printing meshes are available in many different types to cover specific applications and production requirements. Fabric printing re-quires a coarse weave to allow more ink to pass through. Halftone or fine-detail printing requires a tighter weave to hold stencil detail. Electronic and specialized printing requires a metal or polyester/metal hybrid screen that can be heated electrically to facilitate ink flow with thermal ink systems. All meshes must be able to withstand tensioning, stand up to squeegee action, and be impervious to water and reclaiming chemicals. Monofilament polyester has replaced silk as the most widely used fabric in screen printing today.
Mesh count is the term used to describe the number of threads per inch. Meshes range from 40 threads/in. (very coarse, with large openings between threads) up to 400 threads/in. or more. European measurement is in threads per cm. The thread count, thread thickness, and mesh opening measurements are sometimes stamped on the side of the mesh (Figure 2).
Meshes need to be stretched to achieve their potential mesh opening sizes, but be aware that meshes can be off by up to 10% on thread counts, due to the variables of the manufacturing process and individual stretching parameters. For accuracy, measure the mesh count after final stretching (Figure 3).
The printer needs to select the proper mesh for the individual job. Fabric printers might use 80- or 110-thread/in. fabrics for applications where they need to lay down white or light colored inks on dark fabrics. As the mesh count rises, the amount of ink flow and deposit thickness decreases. In graphics applications on non-porous materials, less ink is required for coverage, and higher mesh counts above 300 threads/in. allow finer images and details to be printed. Printing halftones requires specific combinations between line screen and mesh count, or destructive moiré patterns occur.
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