This part specifies the preparation, use and colour reactions of Graff "C" stain. It should be used in conjunction with ISO 9184-1 and, if necessary, with other staining tests defined in ISO 9184-2. Graff "C" stain allows the identification of almost all the common papermaking fibres. However, this calls for a great deal of training and experience. Thus, main applications are: differentiation of chemical, semi-chemical and mechanical pulps, differentiation of kraft and sulfite in hardwood pulps, differentiation of softwood and hardwood pulps (except dissolving grade pulps), differentiation of bleached straw and esparto pulps in softwood pulps.