Pathfinder - Minus Front does not work as I want

[Maria24716256z8zv]

Hi, When I try to do "minus front" on the purple rectangle it becomes a solid half circle not just the "happy smile" as I want. Can anyone help me how to do this? I am stuck! 

[Monika Gause]

Is that red thing a shape or just a stroke? If it's a stroke: outline the stroke first.

[Maria24716256z8zv · Accepted solution]

Thanks, I just figured it out. I expanded the shape and then it worked! 

[Jacob Bugge]

Maria,

If you (ever) wish to keep the stroke in order to enable later editing (which may be more relevant in other more complicated cases where you can also have a Group of paths), you can use an Opacity Mask based upon the original stroked path(s) as follows:

1) Change the Stroke colour to (full) black (and with multiple paths Group them if not already),

2) Select both path(s) and background and click Make (Opacity) Mask (in the Transparency panel).