This part of ISO1209 specifies a simple method for assessing the behaviour of a bar of rigid cellular plasticunder the action of three-point bending.It may be used to determine- either the load for a specified deformation;- or the load at break.The version of the method specified in this part of ISO1209 uses small test specimens and does not producepure bending. Hence it does not permit the calculation of the flexural strength or the apparent flexural modulus(modulus of elasticity). The user is referred to ISO1209-2 for the determination of these parameters.The method is not applicable to cellular plastics in which significant crushing is observed. Numerical valuesshould be compared only when determined on materials of similar physical properties and dimensions.The method is limited to materials of 20 mm thickness or greater.