| Mineral wool or "rock wool" is definitely cheaper and has a an 8 pound psi density. It's definitely not the easiest to work with but I much prefer the feeling of rock wool on my skin to shards of fiberglass! I'd say it matters very little in the end. They both absorb about the same (depending on the thickness and the density) it's more a matter of budget. I think I was $400 in the hole buying OC 703 and 705 when I realized I could get just as much rock wool for half the cost. I finished up the corners of my room with rock wool and have 703 on the walls. Did the job! |