About 5 years ago I used some left over acoustic foam from work. It was used to help with some machine noise and I wasn't involved in the actual use so I can't vouch for any specs. It may just be any brand but was supposed to have some acoustic properties. Any way I just glued on some magnets and stuck it onto the metal external door to my studio to maybe kill standing waves or reflections from the door. A few days ago I walked into the studio and a large chunk of foam from the center of the sheet was lying in the floor! When I felt of the foam it crumbled in my hand. I never wondered if this stuff had a life span. I don't use any other foam but I know it's a widely advertised product to "fix every acoustic problem you have". Anybody else had their studio crumble away?