The TAPPI T 825 standard specifies a test method for the determination of the flat compressive strength of corrugated fibreboards using the rigid support method. This method measures the resistance of corrugated structures (i.e. corrugated peaks) to crushing by applying pressure perpendicular to the surface of the Cardboard under specified conditions. This test is suitable for single-sided corrugated fibreboards and single-layer (double-sided) corrugated fibreboards, but not for double-decked or three-layer corrugated fibreboards because of the possibility of lateral movement of the intermediate interlayer. During the test, the sample is placed on a substantially rigid support and tested at a constant compression rate. It should be noted that the results of the flat compressive strength test using the rigid brace method (TAPPI T 825) and the flexible brace method (TAPPI T 808) are not the same.