Pulp Index Pass through Clauses inside a Paper Supply Contract
Ground paper supply pass-through clauses in verified dry fibre weight, strict index lag rules, and active goods-in batch audits to block supplier overcharges.
Graff C Stain ISO 9184
Fiber Identification
Microscopic chemical staining methods distinguishing wood species and pulping processes establish fiber furnish composition in paper testing laboratories. Graff C stain ISO 9184 defines a standardized chemical reagent and procedure for qualitative fiber analysis of pulp and paper samples. Chemical reaction colors reveal fiber origins, bleaching levels, and pulping methods under optical microscope examination.
The test stops applying to synthetic non-woven materials or non-cellulosic packaging films.
Staining Mechanism
Fiber composition determines physical paper properties, making furnish verification critical for recycled paperboard and fine paper quality control. Applying Graff C stain ISO 9184 produces distinct color reactions based on lignin content, hemicellulose structure, and degree of fiber cooking. Unbleached kraft pulps stain dark blue-green, whereas fully bleached hardwood kraft fibers react to produce clear blue-magenta shades.
Mechanical pulps high in residual lignin turn yellow, enabling precise percentage counts of groundwood components in recycled paperboard stock. Laboratory analysts prepare fiber slides and count color-differentiated fibers under cross-polarized light to verify mill furnish claims. Accurate fiber identification supports recycled content claims and verifies compliance with eco-label certifications.
Chemical age and reagent storage conditions alter stain intensity, requiring fresh dye preparation for reliable results.
Method Scope
Standardized testing rules mandate trained fiber analysts to perform point-count procedures under fixed optical magnification. Applying Graff C stain ISO 9184 yields semi-quantitative furnish estimates, with precision dependent on fiber sampling uniformity. Heavily dyed or deeply pigmented papers require solvent extraction before chemical staining can take place.
The method reaches its limit when evaluating highly refined or damaged cellulose fragments.