This International Standard specifies the methods for the determination of folding endurance of paper using Köhler Molin, Lhomargy, MIT and Schopper testers. It sets out the conditions to be observed when using these instruments, and gives the precautions to be taken in using each instrument. Interpretation of the results is complicated by the fact that the different types of instrument included in this International Standard will give different numerical results for the same test material and they can produce dissimilar rankings for different test materials. Annexes A, B and C give information on the instruments and their maintenance and calibration. NOTE 1 The results obtained with the instruments described are very sensitive to atmospheric conditions under which the test is carried out, particularly humidity. When operated with the standard loads, the Köhler-Molin, Lhomargy and Schopper methods are applicable to paper up to 0,25 mm thick and having a tensile strength greater than 1,33 kN/m. The MIT tester has interchangeable folding heads allowing a range of thicknesses up to 1,25 mm to be accommodated. This International Standard does not state any preferences for any particular method.