Using a loupe to check for errors makes for a good method of identifying flaws and making improvements in the printing process.
Thread diameter vs. open area
A screen’s open area varies quite a bit, depending on the mesh count, thread diameter, and mesh tensioned. The way this affects the printing process can be dramatic if you consider that a poorly tensioned screen with a thick thread and a lower mesh count may have far less open area in the mesh than the thickness of the mesh itself (Figure 4). Though you may be printing through an 86-thread/in. mesh, the amount of ink that goes through the screen is less than typical and a lot of the ink will be stuck in the overlapping parts of the mesh or bounced back into the screen as the printing stroke passes. This is even more important when considering inks that are thicker or have special effect properties like high-density inks or glitters. Talking with your mesh provider can ensure that you get the best quality mesh that will have the appropriate open area ratio and provide the easiest printing quality.
Using a loupe to check used screens can determine quickly if a mesh is stained or clogged. Ink or emulsion particles will occasionally stick in the mesh and this will block areas. To the naked eye, a clogged screen is similar to one that has been stained. A stained screen is one where the actual mesh of the screen has taken on some of the ink color and there are little or no particles actually blocking the openings in the mesh; therefore, printing will not be impeded. While it is true that screens need to be cleaned as much as possible, it is a production fact that the show must go on, and it is useful to know if a screen is going to cause trouble without a cleaning, just look a little stained, or have to be replaced because it cannot be cleaned.
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