Just set the black stroke of the tan rectangle to over print in the attributes panel and leave the tan fill as a knockout
if Wade couldnt help you out, here is my reply:
I dont really understand what youre trying to do here.
Could you explain it a bit more?
I think you mean this, but im probably wrong:
You want the blue and pink shape to only show where they overlap.
If you want to do this, You can do this very easily with the Pathfinder: select all three objects, and choose the Pathfinders: Crop, option.
"Just set the black stroke of the tan rectangle to over print in the attributes panel and leave the tan fill as a knockout"
Wade, would this over print method create an enlarged black stroke around the entire shape?
I am preparing some art work for screen printing and I would like to make traps where colors intersect, but not where they border on empty white space. Maybe this alternate image helps explain what I'm looking for?
You didn't mention silk screen is there anything else we should know about what you are doing like the size or substrate.
What the method I suggest does is knocks out the cyan and magenta sections of the shapes that are under the tan shape but does not knock it out where it lies under the stroke of the tan rectangle. Much like you indicate in your diagram. It does not effect the width of the stroke just the way the art separates.
However since you are working in spot colors and silk screen that means there will be more movement than this technic might be able to compensate for when actually printing the screens.
First depending on what tolerance you expect from the process I would increase weight of the black strokes
and I would use the pathfinder to clip the shapes Minus Front second icon from the top left. I would use another rectangle slightly smaller and the top object and simply hide the current tan rectangle and lock.
TRat will give you two clipped objects with a little extra as your trap.
You still have to set the stroke of the Tan rectangle as overprint or it will knock out the extra regions of the cyan and magenta shapes. Or place the cyan and magenta rectangles on top of the stroke of the tan rectangle and set both those objects to overprint. or they will knock out part of the rule.
Well actually as I think about that last line since the clipped shapes will have stroke has to trap as well. In all cases. So all the strokes have to be set to overprint.
In that case, extending the answer by K-Swoosh in post #2, the simplest/safest approach seems to be to:
1) Skip any stroke on the blue and magenta rectangles,
2) Create a smaller copy of the tan rectangle beneath it and use Pathfinder>Crop to cut the blue and magenta rectangles rectangles (Ungroup and remove the superflouous path).
The tan rectangle with its stroke will then cover the inner edges of the blue and magenta rectangles.
If the blue and magenta rectangles have strokes, a misalignment will be likely to show.
Thanks to everyone for their great help. Here's what I ended up doing:
I "merged" the artwork so it was all butte registered. Then I drew a black rectangle that extended beyond the outer limits of the artwork, put it on top of the artwork and did pathfinder>minus back, this created an empty space in the black rectangle. I hid that so I could work on my artwork. I selected the object I wanted the trap for and increased the stroke to 1.5pt. I then expanded that object and hit pathfinder>merge. I then selected that object and the one it was touching and selected pathfinder>crop. This would normally create the effect I was going for. But just to be sure that nothing got bigger than I wanted, I would select the black rectangle, send it to the back and keep the art in front, select the two and do pathfinder>minus back. This worked pretty well for me!