Well, I tried all those suggestions and none worked. Turns out that I need to slice the scalp into two parts anyway to make chewing show properly. Morphing won't do the job. So I'll leave out the nose and ear, and make the upper part a bit more "schematic". There must be an intrinsic topology problem with the nose; one of those Escher things where the renderer just can't decide what's in or out. (Amapi's internal renderer had the same problem.) Anyway, many thanks for all the suggestions. EnglishBob's idea came closest to working.

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