Angle for spot screen over process

[RickWhiteman]

Here's a design technique I've never seen before: I've got a 5 color job with large fields of spot PMS 144 and some 4/C photos. No problem, right? But in one area, they've got a swoosh of the 144 laying over top of part of a 4/C photo, and the swoosh is set at 60% opacity in InDesign.

Am I going to get a moire in that spot screened area over the 4/C image? Should I just set the spot at the same screen angle as yellow and run with it?

Thanks in advance!

[gordo]

Here's a design technique I've never seen before: I've got a 5 color job with large fields of spot PMS 144 and some 4/C photos. No problem, right? But in one area, they've got a swoosh of the 144 laying over top of part of a 4/C photo, and the swoosh is set at 60% opacity in InDesign.
Am I going to get a moire in that spot screened area over the 4/C image? Should I just set the spot at the same screen angle as yellow and run with it?
Thanks in advance!

Use the screen angle of the least prominent screened process color that's under the PMS 144.
For example, if there's no black - use the black angle, if there's no cyan use the cyan angle, etc.

best, gordon p

[Luc St-Pierre]

As a general rule, I would use angles with opposed colors. A spot color in the red family on the cyan angle, in the green family with magenta and in the blue family with black. 144 is orange, kind of in-between, so I suspect that putting it on the same angle as yellow would be the best guest.

[Sev]

When we have encountered this, we would also use a higher line screen for the fifth color, and use the angles as Luc St-Pierre suggests.

-Sev

[michaelejahn]

Use the screen angle of the least prominent screened process color that's under the PMS 144.

I agree with Dr. Pritchard - as it is somewhat unlikely that they would have positioned a spot orange (Pantone 144) over some image area that is prominently orange (where the predominat colors might be made of yellow or magenta) - so you probably want to select the yellow screen - if they wanted this spot color to not morie against what is under it, I would pick an angle of a color that is NOT under it...

So, for example, if the image under the swoosh is mostly black, it may have a little of all 4 colors, but yellow would probably be the least offensive as the yellow probably be the least noticeable.

[couriergraphics]

If you have stochastic or organic capabilities i would go that way. If not as suggested above a different higher line screen

[Luc St-Pierre]

Be very cautious if you try a higher (or lower) linescreen. On some work, I have done it and the result was a very strange rosette (alignment of all colours) that was noticeable. Not as much as moiré but still introducing a discomfort in the eye.

[Luc St-Pierre]

- if they wanted this spot color to not morie against what is under it, I would pick an angle of a color that is NOT under it...

Designers don't usually care or know enough about this, do not assume they have tought about it.

[MJNC]

Hey PrintPlanet! Happy Friday.
CM&K angles are all 30º away from each other. Yellow would be 15º away from the other 2 colors on each side of it.
It has always been my understanding that Yellow ALWAYS Moirés. You have 4 colors to work with and only 90º to spread the dot angles over. So for each dot to land in an empty space between the dots of the other colors in the rosette, they must be 30º from each other. (It helps me to picture the dot angles on a 4 sided xy grid). The yellow is chosen for the moiré color because it has the least chance of being detected by the naked human eye, and traditionally it goes down on the sheet first; even on a 4/c press.
So, I believe that if you use the yellow angle with the same linescreen as all of the process colors, you will definitely get a moiré!
If you can do a Stochastic Dot, that’s your best bet. Or maybe a higher line screen, in the C, M, or K channels.
Also, is there a chance that you can find a spot color of the correct hue to run as 100% over the area? That way you won’t have any dot to deal with.
Hope this helps. Have a great weekend.
Peace to the PrintPlanet!
_mjnc

[Luc St-Pierre]

Yes, the 15 degree variation is the most likely location to create moiré. In this specific situation, an extra color HAS to be inserted. Beeing an orange, which is somehow dark, it must stay away from cyan, magenta and black where it will definitely cause the moiré... so yellow angle is the only place to be.