Screen E-Book (.PDF) - MacDermid Autotype

Ideal. Find a RIP with an option for ‘stablerosettes’ that are mathematically more resistantto mis-registration but which, in myopinion, do not look so good in the firstplace.Good. Any of the things above that reducethe visibility of a moiré, in particular, printthinner, high quality dots using a low EOM,low Rz film.SummaryThe only tricky thing you need is the Mac-Dermid Autotype Moiré Mesh Calculator tomake sure you have the right screen sets.After that, get yourself a decent stencil systemwith low EOM and low Rz. You get anextra benefit from this. You can use muchlower squeegee pressures, lower viscosityinks and lower snap-off (off-contact). Thismeans you are much gentler to your mesh.So you can go to a finer mesh diameterwhich reduces the intensity of any meshmoiré and gives you a larger dynamic printrange. It is rather surprising that this virtuouscycle exists; but that’s what the mathssays, that’s what we’ve found in real life,and I’m confident that you will find it too.This is the real recipe for success.The science of moiré – the reasonsfor the recipesMoiré scienceIt’s only since the publication in 2000 ofThe Theory of Moiré Phenomenon by IsaacAmidror that it’s become possible to fullyunderstand and model what’s going on.The maths of the MacDermid AutotypeMoiré Mesh Calculator and the FourierTransforms used in MacDermid Autotype’sown Moiré Modeller are all inspired byAmidror’s beautiful book. The screen shotfrom the Modeller gives some idea of thecomplexity of the problem. The bottomright-hand section, for example is theFourier Transform of the combined imageon the bottom left. The bottom-middleimage is the filtered inverse Fourier Transformthat accurately models the perceivedmoiré.104