Oh - I remember now what BBNylon does with IOR. It doesn't deal with reflection. It deals with the bending of light so that it does not pass through so many virtual fibers. When the cloth is sideways, a straight line-of-sight path would seem to indicate that we have to look through a lot of fibers, and it should be very opaque. But if the fibers are refractive this does not happen - the light bends in from the side, towards the skin.

So - the shader has no reflective calculation at all. What you show above is a transparency calculator, and a compensator on the specular due to increasing transparency.

You can use the Fresnel_Blend with freedom, knowing it has nothing to do with the above. Just leave that stuff alone.

If you want, you can keep the IOR parameter - run that into the Fresnel_Blend so everything is in agreement.

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)