That does look painful indeed! Avoid unions whenever possible, particularly on mesh objects. The results can be unpredictable (as you've found!) and the added computation time can become horrendous. Also, unions are really only useful if you're using a transparent material (like glass or water), to eliminate any "seams" between grouped objects. One of the main problems with carving a chunk out of the pretty girl's head is that her head is not a solid object, but hollow and empty. After all, she is a blonde... Okay, this blonde will now go sit in the corner over there ---> ;)