Linerboard made of virgin pulp is called kraftliner, whereas recycled linerboard is known as testliner. The corrugating medium may be recycled medium, called wellenstoff in Europe, or virgin, which is called semichemical medium for the type of pulp used in its production. The borders of these categories becomes blurred when both virgin and recycled fibers are used in making one product.
Kraftliner is made from unprocessed pulp, whereas testliner is created from recycled linerboard. The corrugating material can be either reused or of virgin quality, with the latter being called semichemical medium due to the type of pulp used in its production. When both types of fibers are combined, the lines between these categories become indistinct.