rendering clear acrylic

Hi all,

I have some parts modelled as sheet metal, with multiple folds and
radiused bends etc. The parts are made of acrylic, so when I'm
rendering in photoworks I'm using a very transparent glass material
with low refraction etc.

Problem is that PW always shows black faces some of the radius bends or
on material edges no matter how many reflection and refractions I set
in the PW options (well I've tried up to 8/12).

Is there an easier way to achieve total transparency in this situation.
The rendering times go through the roof using indirect illumination
and very high reflection/refraction values.

Zander

 

See what happens witha refraction of 1 (really no refraction). If the
black spots go away then tweak up to bend the light enough to simulate
glass without getting those black regions.