trying the glass shader on a geometric structure I noticed something odd again.
So I set up some test objects and did test renders.
Tried it with cylinders and unconnected plates,too.Always the same.
Here is another one with single sided square sheets.
And on a Kleinbottle
And yes,I've checked the normals for that one.
Also tried it with larger decay distances - up to 1e+010 - no joy.