Overview
ISO 5270:2022 - "Pulps - Laboratory sheets - Determination of physical properties" specifies the international procedures used to determine the physical properties of laboratory sheets made from all types of pulps. Applicable to sheets prepared in accordance with ISO 5269‑1, ISO 5269‑2 or ISO 5269‑3, the standard defines conditioning, sample selection, test-piece requirements and references the relevant test methods for tensile, tear, burst, air permeance, folding and other physical tests. This fourth edition (2022) replaces ISO 5270:2012 and adapts procedures for situations where material is limited (laboratory-scale testing).
Key topics and requirements
- Scope and applicability: Laboratory sheets prepared by conventional or Rapid‑Köthen formers; procedures tailored for low‑grammage and high‑grammage sheets.
- Conditioning: Standard atmosphere is (23 ± 1) °C and (50 ± 2) % RH (or the tropical alternative) per ISO 187; guidance on preconditioning and moisture‑history (hysteresis) effects.
- Grammage and sheet sizes: Oven‑dry grammage targets are specified (e.g., low‑grammage: 60 ±2 g/m2 conventional or 75 ±2 g/m2 Rapid‑Köthen; high‑grammage: 140 g/m2 ±3 %; z‑directional tests require ≥ 90 g/m2). A minimum area for grammage determination is introduced.
- Test procedures and reporting: Physical tests reference existing ISO methods (tensile - ISO 1924‑2/3, tearing - ISO 1974, bursting - ISO 2758, folding - ISO 5626, air permeance - ISO 5636 parts and optional Oken method ISO 5636‑6, bending - ISO 2493, short‑span compressive - ISO 9895, ring crush - ISO 12192, z‑directional tensile - ISO 15754, flat crush after laboratory fluting - ISO 7263). Results can be reported in index form; apparatus must be calibrated per the referenced standards.
- Optical tests: Conditions and permitted measurements (ISO brightness, CIE whiteness, opacity, scattering/absorption) are specified; limits on performing optical tests on Rapid‑Köthen sheets are noted.
Applications and users
ISO 5270:2022 is intended for:
- Pulp producers and pulp users for specification, quality control and acceptance testing of laboratory pulps.
- R&D and pilot labs developing new pulp formulations or processes where only small sample quantities are available.
- Test laboratories and accreditation bodies performing standardized physical property testing on laboratory sheets.
- Corrugated and paperboard developers using high‑grammage laboratory sheets to evaluate bending, flat crush and ring crush properties.
Practical benefits include consistent comparison between pulps, reproducible small‑scale testing workflows, and harmonized reporting for procurement and R&D decisions.
Related standards
Key referenced standards include ISO 187, ISO 5269‑1/2/3, ISO 1924‑2/3, ISO 1974, ISO 2758, ISO 5626, ISO 5636 series, ISO 2493, ISO 9895, ISO 12192, ISO 15754 and ISO 7263 (flat crush). These define equipment calibration, detailed test methods and calculation/reporting conventions.
