Hi,  It would seem to me that a more physical description for bellows
cloth would be appropriate.  Sometimes this cloth is described by
weight, sometimes by thickness, sometimes by construction and sometimes
by application.  And different supply companies describe it differently.
I also suspect that different manufacturers used different bellows
cloth originally.

I have several organettes plus a couple needing restoration.  The ones
needing restoration are not original and I'm not ripping apart the
others just to measure the cloth.  Perhaps someone who has done a
number of organettes or who has one apart at the moment can measure the
thickness and construction and give an answer to this question for that
particular maker.

Regards
Craig Smith