This part of ISO 8226 specifies a method for the determination of the hygroexpansivity of paper and board when subjected to a change in the relative humidity with which it is in equilibrium from (33 ± 2) % to (84 ± 2) %. The purpose of this part of ISO 8226 is to cover applications of paper and board intended to be used in high humidity conditions, e.g. as found in tropical countries. It may also be useful in determining the effect of excessive moisture to which paper may be subjected for short periods during some printing processes, e.g. offset printing. This method is applicable to paper and board generally. It is not, however, suitable for crêpe papers and corrugated fibreboard.