Fibrous plasterwork is Plaster of Paris, which has been reinforced with jute fibres. Cast fibrous plaster must be formed so that no reinforcement appears on the face of the plaster and it is capable of being fixed to a background. The face is formed by a layer of unreinforced plaster. Reinforcing ribs across the back of a unit enable fixing by nailing, screwing or sometimes tying with wire and wadding. The ribs are comprised of wood laths (sometimes metal formers) covered with hessian soaked plaster.

Plaster is soluble in water and must be protected from the weather so is mainly confined to indoor use. Decorative plaster is fire resistant, is easy to repair and when fitted correctly has a final surface which is joint free.

When casting from rubber moulds taken from natural materials (i.e. timber, stone or brick) it can, itself, have the surface texture of these materials (see imitation oak beams).