Understanding Screen Printing Mesh

By learning the basics of screen mesh and fabric preparation, you can quickly improve the quality of your prints and prevent common screen problems such as pinholes, poor detail, and poor ink coverage. We will begin by explaining mesh counts, weaves, and thread diameter. Once we have a basic understanding of the mesh itself, we can look at stretching and preparing the screen mesh for emulsion.

Polyester monofilament is the best choice for textile screen printing. Stainless steel, nylon, and silk are also available but the polyester is the most common for garment printing. Two different types of mesh weaves are available. Plain weave is a simple one-over/one-under pattern similar to a basket. This allows for a very sharp print when you are screen printing detailed designs. Twill weave is a two-over/two-under pattern. This does not provide the sharp detail like the plain weave but it does allow for more ink to pass through the mesh at higher mesh counts. Most applications are best when printed with plain weave mesh.

Thread thickness is also very important. You may not realize it but many mesh counts that you order are available in different thread sizes. For example, 305 mesh count is available in a thread thickness of 31, 34, and 40 microns. The 305 mesh count screen with 31 micron thread diameter is able to tension 21 to 24 N/cm. This is much less tension than the 40 micron thread (27 to 32 N/cm). You may want the tighter screens for high-end printing but you also must consider the change of ink deposit between the different screens. Even though they are all 305 count screens, they all have different theoretical ink deposits and different fabric thickness.

Mesh color is also something to consider. Customers often ask what the difference is between white and dyed mesh. I always recommend white mesh for counts ranging from 17 meshes/inch to 158 meshes/inch. Anything above 158 meshes/inch it is important to use dyed mesh. White mesh has a tendency to refract light. This causes undercutting of your stencil and you can lose important detail. Yellow mesh reduces refraction because it reduces the travel of ultraviolet light. Dyed mesh will take a longer exposure time but it is a small price to pay when you could be losing fine lines and half-tones. Using proper mesh tensioning procedures will allow for optimum print control and performance. It is important to understand that one definitive mesh tensioning level does not exist. Every mesh count, every thread diameter, and every thread material may tension at different levels.

The final step is preparing your screen properly and consistently. This is just as important as selecting the best mesh count for the job. Mesh pretreatment is the process of cleaning and preparing the screen mesh surface to improve stencil adhesion and eliminate coating defects, with the ultimate goal being optimum stencil performance and durability. It is important to use an abrader/degreaser when you have stretched new mesh material or received new pre-stretched screens.

This will allow your liquid emulsion or capillary film to adhere to the screen better which prevents pinholes, fisheyes, uneven stencil thickness, air pockets, and stencil breakdown. Using household products such as Comet or caustic degreasers is not recommended. The proper chemicals don't just clean the mesh surface, they prepare the mesh for the stencil. If your screen mesh is not virgin, you only need to use a degreaser to treat the surface. Older screen mesh may require a haze remover when it becomes stained.