Overview
ISO 5636-3:2013 - "Paper and board - Determination of air permeance (medium range) - Part 3: Bendtsen method" specifies the Bendtsen method for measuring the air permeance of paper and board using a Bendtsen apparatus. It applies to materials with air permeances between 0.35 µm/(Pa·s) and 15 µm/(Pa·s) when tested with the Bendtsen apparatus and is unsuitable for rough-surfaced materials that cannot be securely clamped.
Key topics and technical requirements
- Test principle: Clamp a test piece between an annular surface and a circular gasket; maintain a small, steady pressure difference (nominally 1.47 kPa) and measure air flow through the known test area.
- Apparatus: Bendtsen apparatus including compressor, pressure stabilizing reservoir, pressure controller (manostat at 1.47 kPa), flowmeter (variable-area or calibrated electronic), and measuring head.
- Flowmeter ranges and resolution: Typical variable-area ranges: 5–150 ml/min, 50–500 ml/min, 300–3000 ml/min with specified resolutions; electronic meters allowed if calibrated to ±5 ml/min or ±5%.
- Test pieces & conditioning: Prepare at least 10 test pieces (recommended size ~100 × 100 mm), condition per ISO 187, and sample per ISO 186 when assessing lots.
- Calibration and accuracy: Flowmeters must be calibrated (variable-area checks with capillary tubes); readings must not deviate by more than ±5% from true value.
- Procedure and reporting: Record readings after stabilization (minimum five seconds); calculate air permeance from measured flow and report results to three significant figures. Report conditioning, number of tests, nominal pressure, flowmeter range, mean permeance(s), and any deviations affecting results.
- Physical requirements: Tubing between head and flowmeter typically 7.0 ± 0.5 mm ID and 690 ± 10 mm length; test area nominally 1 000 ± 20 mm².
Applications
ISO 5636-3:2013 is used for:
- Quality control of paper and board porosity (air permeance testing).
- Material specification and acceptance in printing, converting and packaging industries where controlled porosity affects printing performance, coated substrate behavior, and product consistency.
- Laboratory testing and R&D for product development and comparative performance evaluation.
Who would use this standard
- Paper and board mills (production QC)
- Independent testing laboratories and certification bodies
- Packaging and printing converters assessing substrate suitability
- R&D teams developing papers, boards and specialty porous substrates
Related standards
- ISO 5636 series: Part 4 (Sheffield method), Part 5 (Gurley method), Part 6 (Oken method)
- ISO 186 - Sampling to determine average quality
- ISO 187 - Standard atmosphere for conditioning and testing
Keywords: ISO 5636-3:2013, Bendtsen method, air permeance testing, paper and board, Bendtsen apparatus, air permeance, quality control, paper testing.
