Illustrator CC Minus front not doing what I expect

Question

This hair artwork is composed of dozens of paths.

A path (which has been Brought to Front) represents the hair parting. I'd like to delete this path, so there is a transparent area there. (This is so the hair can be overlaid on artwork of bodies of differing skin tones.)

When I select all the paths and click Minus Front in the Pathfinder panel, I get this:

I must be misusing the tool, but I don't understand how. I have tried both grouping and ungrouping all the paths beneath the parting layer, and moving the parting onto a higher layer than all the hair paths, but it still has the same result.

Answer 1

Sometimes is a little difficult to find the right pathfinder with many vectors. I propose a very efficient alternative.

Imagine my draw is made with many vectors and the light-blue line is the end of the hairs:

• Select this vector > fill it 100% black > Menu Edit > Cut

• Select the hair group (must be a group if it's made with more than a simple vector)

Open the Transparency window > Clic on the right square of the window and uncheck CLip > Menu Edit > Paste in Place

Clic on the left square of the window to go back to the editing area.

You have a transparency mask on the area you want to be transparent

Answer 2

Minus front will delete all objects out of the bottommost one, regardless of grouping. So since you have many objects it simply does not do what you want. So the tool itself is working as designed, just not the way you want.

In general you may do better if you test tools on simpler scenes whenever you have problems to debug your thoughts. Simply because more complex scenes have lots of things going and you may not spot the pattern.

I wouldn't necessarily bother to use pathfinder for this. I would just make a white wedge on top of everything as that is a lot simpler and uses less memory. If i really needed the wedge to be transparent i would just use a knockout group/layer (like done for example here and here). But obviously you can do a copy of the wedge and delete out of every object separately (this can sped up by a action/action and script).

But maybe the easiest method is to just use shape builder select all and alt drag on the wedge.