Method and device for marking fibrous materials

A method of marking fibers, wherein the method includes providing a plurality of fibers; depositing a marker onto at least a portion of the fibers, the depositing being performed with a delivery mechanism comprising one or more outlets; and thereby marking the fibers. Also provided is a device for marking fibers, including a transport system adapted to transport fibers in a direction of a marker delivery apparatus positioned along the transport system; the delivery apparatus includes one or more outlets, adapted to deposit a solution of the marker through the outlets onto at least a portion of the fibers; and thereby marking the fibers. Authentication of a fibrous material using the marking method of the invention followed obtaining a sample of the marked fibers and assaying the sample for the presence of the nucleic acid marker; and thereby determining whether the fibrous material is authentic or counterfeit.