Ultra low weight insulation board

Provided is a lightweight, fibrous thermal insulation panel including high temperature resistant biosoluble inorganic fibers, expanded perlite, binder, and optionally conventional high temperature resistant inorganic fibers. Further provided is a method for preparing a lightweight, fibrous high temperature thermal insulation panel including: (a) providing an aqueous slurry comprising from about 15% to about 90% high temperature resistant biosoluble inorganic fibers, from about 10% to about 80% expanded perlite, at least one of from 0% to about 50% organic binder or from 0% to about 20% inorganic binder by weight, and optionally from 0% to about 70% conventional high temperature resistant fibers; (b) forming the lightweight, fibrous thermal insulation panel by depositing the said aqueous slurry onto a substrate; (c) partially dewatering the slurry on the substrate to form a fibrous layer; and (d) drying the fibrous layer to a moisture content of no greater than about 5% by weight.