Overview
EN ISO 5350-1:2006 - Pulps: Estimation of dirt and shives (Part 1) defines a visual method for estimating visible dirt and shives in laboratory sheets prepared from pulp by inspection with transmitted light. It is principally intended for pulps not manufactured in sheet form but can be applied to mill sheeted pulp when sheets are very opaque (in which case ISO 5350-2 is not applicable). This part is explicitly not intended for recycled pulp. Results are reported as total area of contraries in square millimetres per kilogram (mm²/kg) of oven‑dry pulp.
Key topics and requirements
- Scope & purpose: Visual inspection of laboratory sheets to quantify non‑fibrous dirt and shives (fibre bundles/wood slivers).
- Sampling: Follow ISO 7213 for representative sampling. Total oven‑dry mass of test pieces should be at least 180 g; 100 g is required for the inspection (180 g allows a preliminary test).
- Sample pretreatment: Soak and disintegrate pulp per ISO 5263 (Parts 1–3) using an appropriate number of revolutions to avoid over‑ or under‑disintegration (some grades may need up to 12 000 revolutions).
- Sheet preparation: Prepare laboratory sheets using ISO 5269 methods (conventional or Rapid‑Köthen sheet‑formers).
- Inspection apparatus:
- Viewing table with transmitted artificial daylight; luminance 2 500–3 000 cd/m² at the table surface.
- Comparison chart (Annex A) - transparent film with calibrated spots used for visual classification or calibration of instruments.
- Procedure & classification: Inspect test pieces in transmitted light, estimate area of contraries larger than specified threshold using the comparison chart, and sum areas to give mm²/kg. If contraries exceed 300/kg, inspection sample may be reduced to 50 g (must be reported).
- Reporting & precision: Results include total area (mm²/kg) and, optionally, breakdown by class. Annex B provides an informative instrumental procedure (visual inspection is the normative basis).
Applications and users
- Quality control in pulp mills and paper manufacturing for monitoring cleanliness and defects.
- Laboratory technicians and testing laboratories performing standardized pulp analysis.
- Raw material evaluation for pulp product development and incoming inspection.
- Useful for procurement/specification checks and troubleshooting sheet‑making issues related to contaminant load.
Related standards
- ISO 5350 series: Part 2 (mill sheeted pulp), Part 3 (visual inspection by reflected light, EBA), Part 4 (instrumental inspection by reflected light, EBA).
- Supporting references: ISO 638, ISO 5263‑1/2/3, ISO 5269‑1/2, ISO 7213.
Keywords: EN ISO 5350-1:2006, pulps, dirt and shives, transmitted light inspection, laboratory sheets, pulp testing, sheet-former, disintegrator, pulp quality control.
