The TAPPI T 248 standard specifies a method of laboratory beating of pulp using a PFI mill to assess the paper-making performance of the pulp. The method is suitable for various types of pulp, but may not work well for certain long-fibre pulps, such as cotton pulp. The PFI mill method is particularly well suited for handling smaller quantities of specimens compared to the Valley grinder method described in the TAPPI T 200 standard. During the test, a certain amount of pulp is placed in a PFI mill at a specific concentration. The pulp is pulped to evaluate its mass by relative movement between the grinding roller and the smooth grinding chamber wall and by a specific load applied.