Overview
ISO 5269-1:2005 - "Pulps - Preparation of laboratory sheets for physical testing - Part 1: Conventional sheet-former method" specifies a standardized method for making laboratory sheets from pulp suspensions using a conventional sheet former. The standard describes equipment, sample preparation, sheet forming, couching, pressing, drying and conditioning so that subsequent physical tests reflect the pulp’s intrinsic properties. It applies to most pulps but is not suitable for very long‑fibred pulps (e.g., unshortened cotton or flax) and not intended for preparing sheets for ISO brightness (ISO 3688).
Key topics and technical requirements
- Principle: Form a sheet on a wire screen under suction; press twice at a uniform pressure and dry in contact with a drying plate to prevent shrinkage.
- Sheet former design: Upper stock container and lower drainage vessel with a flat, plain‑woven metallic wire screen (nominal aperture 125 µm; preferred wire diameter 90 µm, range 77–104 µm).
- Agitation/stirring: Mechanical stirrer or controlled air agitation to disperse fibres evenly; guidance on hole size, spacing and timing is provided.
- Stock preparation: Disintegration of unbeaten pulps per ISO 5263; dilute to a mass fraction typically between 0.2 % and 0.5 % and use trial sheets to determine correct stock volume for target grammage.
- Couching and pressing: Couching with specified weight or automatic systems; press to 410 kPa ± 10 kPa for 5 minutes (two pressure cycles).
- Blotters and drying plates: Blotters must be neutral pH, free of sizing agents, specific grammage (~250 g/m² ± 25 g/m²) and defined absorbency; drying plates should be flat and have a surface that promotes sheet adhesion.
- Conditioning: Final conditioning in an atmosphere conforming to ISO 187 to ensure consistent test conditions.
- Limitations: Unsuitable for pulps with very long fibres and for making sheets intended for ISO brightness measurement.
Applications and who uses it
- Laboratories performing physical testing of pulps (strength, porosity, dimensional change, absorbency).
- Pulp and paper R&D teams validating process changes or comparing raw-materials.
- Quality control departments in pulp mills seeking repeatable lab-scale sheet production.
- Instrument manufacturers and testing service providers who require standardized lab sheets.
Using ISO 5269-1 ensures reproducible laboratory sheets that accurately reflect pulp properties and support comparable test results across labs and organizations.
Related standards
Keywords: ISO 5269-1, conventional sheet‑former, pulp laboratory sheets, sheet forming, pulp testing, blotters, pressing, conditioning.
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