I can see I should have composed my original post a little more completely. Yes, the materials do render ok, but i was trying to convey that the affected areas flicker in & out of visibility from second to second, depending on the angle, as I move the cameras viewpoint. I find this to be confusing behavior, as some materials do it, & others in the same model don't. If there's nothing to be done, I'm sure I can live with it, but would still wish to understand it better. :) I've had experience adjusting the normals when importing 3D files, where I've seen really weird behavior by imported surfaces. I'm grateful to ENGELKEN for the tip about using the grouping tool to try and adjust existing poser files; I'll try that tonight! Ditto Cybermonk's suggestion on Objaction Twoface. lalverson,X2000,Huolong,I want to thank you all for your insights into the question. I confess a frustrating problem seems lighter when others are willing to give their time and attention to it! Many thanks!