Acoustic treatment material

I want to build my own bass traps and was wondering if there are any other alternatives to fiberglass and rokwool.  Foam is not a consideration as I don't believe it has the necessary qualities for absorption.  I have heard of cotton batting, does anyone have experience with this material.  The idea of fiberglass makes me itch just thinking about it, but I'm resigned to using it or rokwool if that's all I have.   Please make suggestions and let me know your experiences. 

Owens Corning 703 is a semi-rigid material, unlike the fiberglass insulation you’re thinking of. Nothing to worry about, that’s what all the Pro companies use. You're going to cover it with fabric, right?
I'm going to cover it with burlap. 
Stick with the 703.Cotton batting will do zilch.You want the bass wave to hit the panel and stop.It will sail right on through a soft material.