Screen E-Book (.PDF) - MacDermid Autotype

Edge of the mesh, relatively high pressure required,large distortionIt’s therefore important to make sure yourimage area is not too close to the frame,both in the lengthwise and crosswise direction.What happens if you get too close to theframe? First you get large image distortion.Second, you are forced to use a largersqueegee pressure which can damage thesqueegee and can also cause judder andextra dot gain (graphics) or positive sawtoothing(technical).There is also evidence that the squeegeegets distorted near the edge and cannotdo a good job of scraping off the excessink, thereby giving a higher ink deposit inthe areas near the frame.Of course, as you go to lower and lowersnap-off, the problems get less and less soyou can go to a larger % image size.Poor cleaningFailure to properly clean and reclaim amesh gives you ghost images. For manyyears the effect puzzled us. Often wecouldn’t see any residue on the mesh, yetthe ghost was still there. Where was itcoming from?The answer was that the knuckles of themesh are where most of the ghosts hideout. Why is this important? Because theamount of ink held in the mesh, and theamount of ink remaining on the meshwhen it comes out of the ink both dependstrongly on the knuckles.A small amount of ghost hiding in thecorner of a knuckle is enough to changethe printed ink volume. See Steve’s meshmarking section for his hypothesis aboutmesh marking.Lower snap-off (off contact) and relatively lower pressure/distortion75