Hornification

Papermaking Consequence

Recycled pulp slurries exhibiting severe microfibril collapse produce paper sheets with reduced tensile strength, lower bursting indices, and diminished folding endurance. Inflexible fibers fail to conform to one another during wet pressing, yielding a porous, bulky sheet structure with weak inter-fiber bonding. Papermakers must apply supplementary mechanical refining or add synthetic dry-strength resins to compensate for lost fiber flexibility.

Recovery Treatment

Chemical conditioning with sodium hydroxide at elevated temperatures swells collapsed fiber walls and partially restores conformability. Mechanical refining re-fibrillates the external wall surface by stripping away the inert outer layers, though it shortens brittle recycled fibers. Enzymatic treatment using cellulases increases fiber wall permeability without inducing severe fiber breakage.