Patent ID: 6919132

Claim:
A panel comprising: mineral fibers, perlite, cellulosic fibers, and binder; the mineral fibers comprising about 50% to about 85%, the perlite comprising 0% to about 18%, the cellulosic fiber comprising about 2% to about 7% and the binder comprising about 6% to about 15%, of a dry solids weight of said panel; wherein from about 30% to about 65% of the mineral fibers are nodulated and the perlite has a density in the range from about 7 to about 20 pcf; whereby a resistivity value in the range from about 200,000 to about 400,000 mks rayls/m and a hardness value in the range from about 85 to about 130 lbf is achieved in the panel.