Abstract: A machine for cutting fiberglass board of the type having an impermeable barrier, such as foil, on one face thereof. As a board of fiberglass moves through the machine, the leading edge of the foil is bent down from it normal plane of travel so that a knife edge which is below this plane of travel will be inserted between the foil and remainder of the board.The board is then maintained in its normal plane of travel and the knife edge being below the board forces the barrier to shear away from the board as the board passes through the machine. The knife edge cleans the loosened foil to remove most of the insulation material that might remain adhered thereto.