Which version of matplotlib are you using? IIRC, this was a bug that was fixed after 1.2.1.

Found this issue on 1.2.1 but i checked it now on 1.3.0rc2 and there it exists as well

import matplotlib
matplotlib.version
'1.3.0rc2'

Sorry for missing the version in initial post

Confirmed. I suspect there is some logic in the pdf code which checks for a "none" color and then skips the fill section (which included hatching)...

You are right. In matplotlib/lib/matplotlib/backends/backend_pdf.py, there is nothing filled when no facecolor is specified. I did a quick test by specifying filled manually in this case, and the result looks as expected.

def draw_path_collection(self, gc, master_transform, paths, all_transforms,
                         offsets, offsetTrans, facecolors, edgecolors,
                         linewidths, linestyles, antialiaseds, urls,
                         offset_position):
    facecolors = np.asarray(facecolors)
    edgecolors = np.asarray(edgecolors)

    if not len(facecolors):
        filled = False
    else:
    ..........

@claria: Could you test the attached patch?

Applying this patch against 1.3.0 fixes the issue for me. Thanks alot

Change looks good to me. I'm guessing the travis test failures are not a coincidence, would you mind looking into this and I'd be happy to merge.

Rebased and unit tests (hopefully) fixed.