This part of ISO 9184 specifies the preparation, use and colour reactions of Herzberg stain in fibre furnish analysis. It should be used in conjunction with ISO 9184-1 and, if necessary, with other staining tests defined in ISO 9184-2. The Herzberg staining test is applicable to the qualitative and quantitative differentiation between chemical, mechanical and rag pulps. The stain also permits the qualitative identification of semi-chemical pulp as well as the differentiation between regenerated cellulose fibres (viscose, etc.) and synthetic fibres.