I've used it. bpape sells it sensiblesoundsolutions.com. He has excellent prices on raw materials for diy acoustic treatment. The cotton is made from recycled denim. It absorbs better than FG, but it is floppy. It has a dusty odor when not covered, but it's ugly so it needs covering. It is totally non-toxic, no formaldehyde like most FG products. It is treated with boric acid to prevent mold and insects. Thicker will absorb lower frequencies and broader band of frequencies, same as any absorber in that respect. You definitely need a mask to prevent absorbing too much high freqs. I have used kraft paper which was a little too much reflection for me, and I also used pallette wrap plastic, which was good, but too little reflection, still experimenting. This nicest thing about the cotton is that it is cheap. The drag is that it is totally floppy so you need frame, or hang it like a tapestry.
