Patent ID: 8372241

Claim:
A method for manufacturing a sheet material including at least two fibrous plies juxtaposed on each other, said method comprising: making a first paper ply, including at least one elongate area of zero thickness, by filtration of an aqueous suspension of fibers on a wire cloth of a first round mould or of a former, making a second paper ply on a wire cloth of a second round mould in order to form at least one recess in the second ply, and then positioning at least one at least partly transparent element between the first and second plies still moist so that edges of the at least partly transparent element are inserted between the first and second plies, and joining the first and second plies so that said at least one recess of the second ply, said at least one at least partly transparent element, and said at least one zero thickness elongate area of the first ply are located facing each other, drying the thereby obtained structure, said at least one at least partly transparent element being a continuous strip and having a same length as said at least one zero thickness elongate area of the first ply.