D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
D21F11/00—Processes for making continuous lengths of paper, or of cardboard, or of wet web for fibre board production, on paper-making machines
D21F11/06—Processes for making continuous lengths of paper, or of cardboard, or of wet web for fibre board production, on paper-making machines of the cylinder type
D21F11/08—Processes for making continuous lengths of paper, or of cardboard, or of wet web for fibre board production, on paper-making machines of the cylinder type paper or board consisting of two or more layers