Great thread.
Not sure what the fuss is about...but great thread.
If you're mounting panels on walls...a nice tighter-weave cloth that breathes, is all that is needed.
The fiberglass/rockwool inside is not going to move once the panel is.
(Didn't we just talk about this in another thread?)
If you're doing ceiling panels/clouds, and you're very sensitive to fiberglass or any kind of particles...use some 0.4 mil plastic to wrap the insulation panels before putting them into the frames....or you can double layer with the cloth material. I would use a polyester felt for the inner layer, and then your outer cloth. The two layers will crisscross and there should not be anything falling out.
I recently used the plastic wrap approach for traps that are going to be mobile, so considering the constant moving, I wanted to be 100% sure the particles would forever be contained, as I hate fiberglass. The plastic is so sheer...that it will have zero effect on the audio. The outer cloth will have more effect on high frequencies than the 0.4 mil plastic.
The biggest concern with insulation particles happens during the building/installing...so you want to make your traps outside or somewhere where they wont be a problem.
Also...there is to date, no proof that fiberglass or rockwool cause cancer. all the research shows that any particles getting into the lungs will dissolve. They will certainly irritate, but actually...cotton fibers tend NOT to dissolve when inhaled...so think about that next time you clean the lint off your clothes dryer screen....
...but I don't worry about that either, and I prefer cotton clothes over anything synthetic.
Real-world concern about the cotton cloth is that it will absorb moisture and potentially sag/droop...so stretch it real tight.
Polyester will not do that.
