Overview
EN ISO 186:2002 - Paper and board - Sampling to determine average quality (ISO 186:2002) specifies a standardized method for obtaining a representative sample from a lot of paper or board (including solid and corrugated fibreboard) for testing whether the lot’s average quality meets agreed specifications. It defines sampling procedures for routine quality control and for buyer–seller dispute resolution, and notes limits (for example, the procedure is invalid if less than 50% of a lot is available unless otherwise agreed). The method is explicitly not intended to assess within-lot variability.
Key topics and technical requirements
- Scope and purpose: Sampling to determine average quality of a defined lot; conditions for dispute resolution; guidance when sampling is impractical (normative Annex A).
- Definitions: Lot, unit (reel, bale, pallet, parcel), sheet, specimen, sample, test piece, and “selected at random.”
- Selection of units: Table-based rules - e.g., for lots of 1–5 units select all; for 6–399 units select n + 20 at random; for 400 or more select 20 units at random.
- Selection of sheets/windows:
- Unwrapped units: avoid damaged sheets and the three outermost undamaged sheets; take the same number of sheets from each selected unit.
- Reels/rolls: remove damaged layers plus three undamaged layers for paper (grammage < 225 g/m2) or one for board (≥ 225 g/m2); vary sheet positions so each 400 mm section is represented.
- Wrapped or restricted units: cut random windows (e.g., 300 × 450 mm or 450 × 450 mm if machine direction unknown) and take sheets through the windows.
- Minimum sheets/articles: Tables specify minimum numbers (e.g., minimum 10 sheets for lots ≤1 000, 15 for 1 001–5 000, 20 for >5 000).
- Specimen and test-piece preparation:
- Specimens must be uniform size; recommended specimen sizes include at least 300 mm (CD) × 450 mm (MD) when machine direction is known, or square 450 × 450 mm if unknown.
- For smaller sheets, specimen surface area should be between 0.100 m2 and 0.135 m2.
- Handling and marking: Keep specimens flat, avoid contamination or damage, mark specimens indelibly and unambiguously. Re-sampling requires a new sample following the same standard.
- Limitations: Unsuitable for measuring within-lot variability; sampling invalid if less than 50% of lot is available (unless agreed).
Applications and users
- Quality control and acceptance testing in paper mills and converters
- Procurement and incoming inspection for printers, packaging manufacturers and converters
- Independent testing laboratories and certification bodies
- Commercial dispute resolution between buyers and sellers
- Customs and inspection authorities when material cannot be fully unwrapped
Users: QC managers, production engineers, laboratory technicians, contract managers, and procurement specialists in the paper, board and packaging sectors.
Related standards
- ISO 4046 - Vocabulary for paper, board and pulp terms (referenced for definitions)
- Normative Annex A in EN ISO 186:2002 provides guidance when standard sampling is impossible, impractical or inappropriate.
