Fibrous casing is a cellulose-based casing strengthened with natural long-fibered abaca paper, sometimes called manila hemp fiber, which combines exceptionally high tensile strength with consistent extrusion properties in a form that renders it ideally suited for sausage casings. Due to its strength and dimensional stability, fibrous casing is traditionally seen as one of the most versatile and comprehensive packaging materials.
As a further step in the development of strong fibrous casings for large calibers, a layer of synthetic material, (e.g. PVDC) was added to the inside or outside of the casings (coated fibrous casings). The coating made the casing mechanically very resistant and created a complete barrier for gases, i.e. no evaporation losses can occur .
However, fibrous casings with an inside or outside synthetic coating cannot be used for products to be smoked, as no smoke penetration is possible, and for products to be dried and fermented, as no water vapour evaporation is possible. They are mainly used for cooked sausages of the raw-cooked and the precooked-cooked type. The main advantage of coated fibrous casings for cooked sausages is the casing wall tightly enclosing the sausage mix and the easy peeling. As smoke does not penetrate through coated fibrous casings, smoke flavour can be added during manufacture of the sausage mix if desired.