6 Replies Latest reply on Apr 15, 2010 3:27 PM by tiredew

    How to make clipping mask using empty space?


      Disclosure: I don't have much experience with Illustrator.




      First I'll tell you what I'm trying to accomplish, then I'll share my idea for how to do it.


      I'm trying to trap the blue and magenta shapes, but only the parts that touch the brown rectangle.


      I figured I would just make a stroke around the blue and magenta shapes. But the problem is I don't want the parts in the white space to expand (as it would if a stroke were applied). So I'm thinking that if I make a white area that covers the entire image, but has the area where any color is cut out, I will put this white area over all the other colors so when the magenta shape gets the stroke, it will not be visible (the white will cover it).


      Is there a way to do this? A better way to accomplish this goal?

        • 1. Re: How to make clipping mask using empty space?
          Wade_Zimmerman Level 6

          Just set the black stroke of the tan rectangle to over print in the attributes panel and leave the tan fill as a knockout

          • 2. Re: How to make clipping mask using empty space?
            kas8 Level 1

            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.

            • 3. Re: How to make clipping mask using empty space?
              tiredew Level 1

              "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?



              • 4. Re: How to make clipping mask using empty space?
                Wade_Zimmerman Level 6

                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.

                • 5. Re: How to make clipping mask using empty space?
                  Jacob Bugge MVP & Adobe Community Professional



                  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.

                  • 6. Re: How to make clipping mask using empty space?
                    tiredew Level 1

                    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!