In a device (1) for the treatment of filter material used in tobacco products, a continuous stream (F) of filter material is advanced along a predetermined feed path (A) above a plurality of nozzles (6) delivering a plasticizer fluid (P); the nozzles are carried on a table (5), which presents a longitudinal dimension greater than the transverse dimension of the stream (F) and is rotatable relative to the stream so as to increase or reduce the number of nozzles (6) directed at the stream (F), according to the relative positioning of the stream (F) and the table (5).