A process for producing pellets or granules comprising fibers of a lignocellulousic material, for use as a feedstock in plastics manufacture, conveying in a dry or wet air stream and applying to the fibers a liquid formulation comprising one or more polymers, monomers, or oligomers, forming the fibers into a solid product, and breaking down the solid product to produce said pellets or granules. Typically the conduit conveys the fibers in a plant for manufacture of fiber board.