Abstract: Before being processed in a pneumatic separator or classifier (13), a stream of cut tobacco, travelling to the separator on a conveyor (12), is passed through an opener (11) to open up tangled masses of tobacco that cannot be handled by the separator. The opener comprises carded rollers (1, 2, 3 and 4) having sequentially increasing peripheral velocities. Rollers (1,2 and 4) rotate in the same direction as each other, away from the conveyor, so that tobacco passes over the top of each roller, whereas roller (3) rotates in the opposite direction. The carding pins on rollers (1, 2 and 4) are inclined 5.degree. to the normal, in the direction of rotation. The pins on roller (3) are inclined at 30.degree., also in the direction of rotation, so as to trap the tobacco as it is moved around underside of the roller.