Normally composed of textile fibres, mineral and/or wood fibres can be added to the pre-polymerized felt. It is called pre-polymerized felt because the resin is not cured.
Whatever the origin of the fibres may be they can be piled with thermosetting resin The resins may be phenolic or non-phenolic and may also contain neutral or expandable fireproofing agents.

Among the main uses of pre-polymerized felt is that it can be subsequently moulded or shaped in a hot mould.

Weight: From 600 gr to 2500 gr/m2
Presentation: in polyethylene bundles of sheets