ISO 5350-2:2006

Overview

ISO 5350-2:2006 - "Pulps - Estimation of dirt and shives - Part 2: Inspection of mill sheeted pulp by transmitted light" defines a visual method to estimate visible dirt and shives in mill-sheeted pulp using transmitted light. The method reports the total area of contraries as square millimetres per kilogram (mm²/kg) of oven-dry pulp. It applies to most sheeted pulps (typical maximum grammage 800–1 000 g/m²) but excludes unbleached kraft pulps, recycled pulp, and any sheets too opaque to permit reliable transmitted-light estimation.

Key topics and technical requirements

• Principle: Inspect wet or sufficiently transparent test pieces in transmitted light using a viewing table and a normative comparison chart (Annex A) to size and classify contraries.
• Sampling & sample size: Select representative test pieces per ISO 7213; inspect at least 300 g oven-dry pulp (total area ≥ 0.5 m²). If preliminary counts exceed 300 contraries/kg, inspection mass may be reduced to 100 g (must be reported).
• Minimum detectable size: Only contraries ≥ 0.04 mm² are counted.
• Size classes:
  • Class 1: > 5 mm²
  • Class 2: 1.00–4.99 mm² (log mean 2.482 mm²)
  • Class 3: 0.40–0.99 mm² (log mean 0.651 mm²)
  • Class 4: 0.15–0.39 mm² (log mean 0.251 mm²)
  • Class 5: 0.04–0.14 mm² (log mean 0.080 mm²) - optional
• Apparatus & lighting: Viewing-table luminance 2 500–3 000 cd/m²; avoid daylight and direct external light. Do not use photocopies of the comparison chart.
• Calculation: Total area X (mm²/kg) = Σ (c_i × n_i) / m, where c_i is the class logarithmic mean area, n_i is the count in class i, and m is oven-dry mass (kg). For contraries > 5 mm² use true measured area.
• Reporting: Report mm²/kg (nearest integer; values < 5 mm²/kg to one decimal), and note any deviations (e.g., omitted wetting, reduced sample).

Applications and users

• Who uses it: pulp and paper mill QA/QC teams, independent testing laboratories, pulp traders, buyers, and standards organizations.
• Practical uses:
  • Acceptance testing of mill-sheeted pulp in commercial transactions
  • Process control and supplier quality monitoring
  • Comparative audits and dispute resolution over pulp cleanliness
  • Baseline data for process improvements and defect reduction

Related standards

• ISO 5350-1: Inspection of laboratory sheets by transmitted light (for thick/opaque sheets)
• ISO 5350-3 & ISO 5350-4: Reflected-light visual and instrumental EBA methods
• ISO 638: Determination of dry matter content
• ISO 7213: Sampling for testing

Keywords: ISO 5350-2, pulp testing, dirt and shives, transmitted light inspection, mill sheeted pulp, pulp quality control, comparison chart, viewing table.