Polymer Barrier Coatings and Pulpability Test Standards
Polymer barrier paperboard compliance requires passing 0.15mm laboratory slot screening with under 15 percent reject mass to prevent EPR fee penalties.
ISO 5350 Dirt Count
Optical Inspection
Visual quantification of non-bleachable specks and foreign particles in pulp handsheets determines optical cleanliness standards for papermaking stock. Performing an ISO 5350 dirt count measures the equivalent black area of dark spots per square meter of test sheet. Technicians inspect transmitted or reflected light images across translucent laboratory sheets to categorize dirt particles by size class.
High dirt levels degrade sheet appearance and cause printing defects on converted paperboard packaging.
Contaminant Measurement
Test protocols define minimum particle area thresholds and illumination angle rules for manual or automated image analysis. Applying ISO 5350 dirt count standards provides paper mills with reproducible purity metrics across virgin and recycled pulp supplies. Visual specks originate from bark remnants, plastic contaminants, sticky adhesives, or carbonized rubber particles.
Automated optical scanners count particles rapidly, reducing human subjective grading errors during quality control checks. Particle size distribution data highlights specific contamination sources during pulping and deinking operations.
Purity Standard
Product specifications enforce upper boundaries on visible speck area for food contact and graphic paper grades. Dirt count metrics lose validity when evaluating heavily dyed or opaque filled paper boards where optical transmission fails. Process control relies on dirt quantification to schedule screen maintenance and pulper cleaning cycles.
Clean pulp stock prevents visual defects on finished packaging boards.