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Halftone Angles Demystified: Enhance Print Quality for Superior Screen Printing

Does the angle I setup for my halftones matter? Yes, absolutely!

The angle of a halftone line screen has everything to do with the overall image clarity and the technical avoidance of moiré. Moiré is an undesirable repeating pattern that develops when two halftone angles interface in conflict.

When the angle at which your halftone line screen is setup wrong will create a moiré with your mesh. This is a major concern for screen printers but it’s also something that’s easy to avoid.

The best halftone angle for humans to view a printed halftone is 45 degrees. Technically best, but as screen printers we cannot use this angle. This is the angle used as often as possible when printing images using offset or digitally. There is no concern with moiré because paper and plates have no angle of their own like our stretched mesh.

Proper mesh is stretched onto a frame at 90 degrees giving it an angle all its own. Adding to that a conflicting angle from your halftone line screen film will develop an instant moiré.

So just pick another angle, right? Right and wrong. There are many angles that will be in conflict with your mesh and others that do not moiré but deliver a less than desirable visual result. Again, a concern but something really easy to understand and avoid. This article will teach you all you need to know.

One goal is to use a halftone line screen and angle that not only does not moiré with the mesh but delivers the best looking print possible.

There are varying opinions over what angle is best but, technically and most importantly, visually 22.5 degrees being half of 45 and closer to horizontal than vertical is the best angle to choose for all your halftone work. Use the same angle 22.5 degree angle for all colors when printing one color, multi-color, and even CMYK prints. For this reason, AccuRIP® properly defaults to a single 22.5 degree angle.

As the angle of halftones lay down closer to 0 (less than 45 degrees) on a protractor, they blend more easily with the optics of the human eye. Halftones that are tight or more vertical than 45 degrees such as 61 or 75 degrees will also reduce or eliminate moiré but deliver a visual frequency within the finished print. After all, we want to look at the overall print and enjoy it, not see the technical line screen values that produced it.

Bottom line, in the screen print industry use the angle of 22.5 degrees for all your screens and halftones regardless of the style of printing you are doing. Tonal single color, multi-color, Spot Process® Separation Studio®, and CMYK – all screens should share the same angle and all angles should be set at 22.5 degrees.

One angle for all your needs. Now you know.

Simple and totally correct.

 

 

(c) Freehand Library Article / AccuRIP / Separation Studio NXT / Spot Process / Dmax / Amaze-Ink / DarkStar

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