ISO 5636-5 Air Permeability test Paper and board

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Mechanical testing in the packaging industry determines the packaging's resistance to compression, impact, and tension, directly ensuring the safety of contents during storage and transportation. UnitedTest can cover comprehensive mechanical testing for packaging, complying with ISO, ASTM Standards, and provides customized testing solutions for compression, drop, tear, and more.

Mechanical testing in the transportation industry concerns the load-bearing and fatigue resistance performance of core components such as vehicles, tracks, and containers, directly ensuring transport safety and equipment durability. UnitedTest can cover mechanical testing for all types of transportation materials, complying with national and international standards, and provides customized testing solutions including tensile, fatigue, and impact tests.

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Tensile test evaluates material resistance to stretching, measuring strength/elongation critical for quality control. UnitedTest offers universal tensile testers (10-600KN) compliant with ASTM/ISO standards, providing tailored solutions for metals, polymers, medical & industrial materials.

Compression test assesses material resistance to compressive loads, measuring strength/deformation critical for quality validation. UnitedTest offers compression testing machines compliant with ASTM/ISO standards, providing tailored solutions for concrete, plastics, metals and industrial components.

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Torsion Test evaluates material resistance to rotational forces, measuring torsional strength/ductility critical for fasteners, insulators, shafts. UnitedTest offers torsion testers compliant with ASTM A938/ISO 16047, providing tailored solutions for automotive, aerospace, fastener industries.

Fatigue Test assesses material durability under cyclic loading, critical for predicting service life of industrial components. UnitedTest offers fatigue testing systems (axial/bending/torsion) compliant with ASTM E466/ISO 12106, providing tailored solutions for automotive, aerospace and manufacturing sectors.

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ISO 5636-5 Gurley Air Permeance Tester for Paper and Board | UnitedTest

UnitedTest manufactures professional ISO 5636-5 Gurley air permeance testers, dedicated to accurate medium-range porosity testing for paper and paperboard materials in packaging and pulp & paper industries.

ISO 5636-5 Paper and board — Determination of air permeance (medium range) — Part 5: Gurley method is the international standard that adopts the classic Gurley test principle to evaluate key ventilation performance of paper and board. It quantitatively measures two core physical indicators:air permeance and air resistance for medium-porosity paper-based materials.

This standard covers a precise medium testing range with air permeance from 0.1 μm/(Pa·s) to 100 μm/(Pa·s). Our ISO 5636-5 compliant Gurley tester delivers stable, repeatable air permeability data, supporting routine quality inspection, material grading, and product R&D for all qualified paper and board products within the standard porosity scope.

Test Principle

The test relies on gravity-driven constant pressure differential:

An inner weighted cylinder floats vertically inside an outer cylinder filled with sealing oil, generating stable air pressure from the cylinder’s dead weight.

A flat paper test piece is clamped over a circular measuring orifice, separating pressurized air above the sample from ambient air below.

Pressurized air penetrates through the sample, making the inner cylinder sink steadily in the sealing fluid.

The timer records the time consumed for a fixed air volume (typically 100 mL) to pass through the specimen; this time value is defined as air resistance.

Air permeance is mathematically converted from air resistance via a standardized formula based on fixed test area and pressure difference.

Test Sample information:

Quantity: minimum 10 test pieces (5 with side 1 up, 5 with side 1 down)

Size: adequately 100 mm × 100 mm

Surface: free from folds, wrinkles, holes, watermarks

Complete Test Equipment of ISO 5636-5 Air Permeability test Paper and board

Core Gurley Apparatus

Recommend UnitedTest Gas Permeability Tester - Gas Permeation Analyzer;

Outer cylinder: Pre-filled with specified sealing oil, with graduated volume scale (50 mL, 100 mL markings).

Floating inner cylinder: Open-top, free-sliding, provides fixed test pressure (average pressure difference = 1.22 kPa).

Clamping assembly (base unit):

Upper/lower clamping plates with concentric circular aperture; three clamping force options: hand screw capstan, 901 g dead-weight lever, pneumatic clamp.

Standard clamping force requirement: 180 ± 30 N for uniform loading and minimal operator deviation.

Rubber sealing gasket (mounted in upper plate groove):

Dimension: Inner diameter 28.6 ± 0.1 mm (effective test area = 642 mm²), outer diameter 35.2 ± 0.1 mm, groove depth 0.45 ± 0.05 mm, gasket thickness 0.7–1.0 mm.

Material: Oil-resistant non-oxidizing elastic rubber, hardness 50 IRHD (per ISO 48) to eliminate edge air leakage between sample and fixture.

ISO 5636-5 Air Permeability test Paper and board

Sealing Fluid (Oil)

Density: 860 ± 30 kg/m³

Viscosity: 16–19 cP at 20 °C (ISO 3104 kinematic viscosity test)

Flash point ≥ 135 °C (low-volatility lightweight paraffin oil)

Key Test Parameters

Parameter	Value / Stipulation
Test area	642 mm² (Ø 28.6 mm gasket)
Nominal air volume	100 mL (timed over two consecutive 50 mL marks)
Mean pressure diff.	~1.22 kPa (from cylinder weight)
Clamping force	180 ± 30 N
Time reading	to nearest 0.1 s
Applicable range	0.1 – 100 μm/(Pa·s) air permeance

Standard Test Procedures of ISO 5636-5 Air Permeability test Paper and board

Instrument preparation & calibration

Level the apparatus, fill outer cylinder with qualified sealing oil.

Calibrate volume accuracy following Annex A normative procedure.

Zero leakage check: Clamp non-porous flat plate; confirm zero air flow reading (no cylinder sinking).

Sample clamping

Set clamping force to stable 180 ± 30 N; place one flat test piece between upper/lower plates, align concentrically with gasket aperture.

Timing measurement rules

General medium-permeability paper: Record time for two consecutive 50 mL scale marks (total 100 mL).

Low-permeability dense paper/board: Timing can stop after first 50 mL interval, convert result to equivalent 100 mL time.

Highly porous open paper: Extend measured air volume beyond 100 mL, normalize time to 100 mL for unified calculation.

If cylinder steady flow only starts after 50 mL mark, initiate timing at the 50 mL graduation line.

Repeat testing: Complete all 10 specimens (5 each side up/down) under vibration-free environment.

Data sorting: Calculate average air resistance time t, then compute air permeance via Equation.

Industrial Application Fields

The Gurley air permeance test is a core quality control index across paper-related industries:

Packaging industry: Food packaging paper, greaseproof paper, corrugated board, barrier coated paper. Permeance controls gas exchange, shelf life, and aroma retention of packaged goods.

Battery materials: Evaluation of separator films, breathable membranes, and polymer-based components.

Printing & publishing paper: Newsprint, offset printing paper, coated art paper. Air permeance determines ink absorption rate, dot reproduction quality, and print uniformity.

Special functional paper: Filter paper, tea bag paper, release paper, medical wrapping paper. Controlled porosity ensures filtration efficiency, liquid wicking, and sterile barrier performance.

Paper converting & coating production: Monitor sizing efficiency, coating layer uniformity, and sealing performance of laminated paper substrates.

Paper pulp R&D: Evaluate pulp fiber fibrillation, filler loading impact on sheet compactness and porosity.

Related Test Stanard:

ISO 5636-5	Paper and board. Determination of air permeance (medium range). Part 5: Gurley method
TAPPI T 460	Air resistance of paper (Gurley method)
GB/T 458	Paper and board - Determination of air permeance
ISO 5636-3	Bendtsen method: Widely used for low-to-medium permeance paper, different pressure and fixture design vs Gurley.
ISO 5636-4	Sheffield method: For lower permeance range (0.02–25 μm/(Pa·s)), alternative floating-cylinder apparatus.
ISO 5636-6	Oken method: Full-range air permeance test method without upper/lower measuring limit, different mechanical principle.

Importance of This Test for Paper & Board Materials

Core porosity characterization: Air permeance directly reflects the internal void structure of paper sheets (fiber packing density, pore size distribution). It is the most universal quantitative indicator of paper porosity.

Predict end-use performance:

Low permeance (high Gurley time): Dense, barrier-efficient paper for food packaging, oil-proof wrapping, vacuum packaging.

High permeance (low Gurley time): Breathable filter paper, tea bag paper, highly absorbent printing paper.

Manufacturing process control:

Monitor pulp beating degree: More refined fiber reduces sheet porosity and air permeance.

Check sizing/coating consistency: Uniform coating lowers air permeance; uneven coating causes scattered test data.

Control calendering pressure: Higher calender load compresses paper, decreasing air flow through the sheet.

Quality consistency & cross-lab comparability: Annex C provides CEPI interlaboratory precision data (repeatability & reproducibility limits). The standardized Gurley method eliminates subjective operator errors, enabling consistent batch acceptance and cross-factory product specification alignment.

Product specification compliance: Most paper product international purchase contracts reference ISO 5636-5 Gurley permeance as a mandatory acceptance criterion to avoid batch quality disputes.

Raw material development benchmark: Compare different pulp, filler, coating formulas to optimize balance between breathability and barrier properties for custom functional paper products.

Keywords: UnitedTest ISO 5636-5 tester, ISO 5636-5 Gurley air permeance tester, paper board air resistance test machine, medium range air permeability tester, ISO 5636-5 Gurley method paper porosity testing, 0.1 to 100 μm/(Pa·s) paper board air permeance test equipment, medium range air resistance analyzer for packaging paper, pulp and paper Gurley air permeability quality tester

Gas Permeability Tester is a multi-functional lab instrument dedicated to gas barrier performance testing, gas transmission rate (GTR). Conform to ISO 15105-1, ISO 2556, ASTM D1434, Widely adopted as standard QC testing equipment for flexible packaging, plastic manufacturing and new energy sectors.

Textile Air Permeability Testing Machine is used to determine the air permeability of fabric totally automatically. Auto Air Permeability Tester complies with ASTM D737, ISO 9237, ISO 7231, ISO 5636, BS 5636, DIN 53887, JIS L1096, BS 5636 etc.

Q1: What is ISO 5636-5 exactly?

A1: ISO 5636-5:2013 is an international standard for measuring medium-range air permeance and air resistance of paper and paperboard using the Gurley testing apparatus. It belongs to the ISO 5636 series for paper air permeability, specifying the gravity-driven floating cylinder test principle, equipment requirements, specimen rules, test procedures, calculation formulas and reporting rules.

Q2: How many test specimens are required, and why test both sides of paper?

A2: A minimum of 10 test pieces total: 5 pieces with side 1 facing up, 5 pieces with side 1 facing down.

Many papers have an obvious two-sided difference (e.g., coated paper, newsprint, linerboard). Testing both sides eliminates surface bias and reflects the overall average permeability of the whole sheet.

Q3: What two key indicators does this standard measure?

A3: Air resistance: Unit s/(100 mL), the raw timed result for 100 mL air passing through the sample.

Air permeance: Unit μm/(Pa·s), calculated from air resistance, representing air flow rate per unit area under unit pressure difference.

Q4: What is the mandatory clamping force required by ISO 5636-5? Why is it strictly controlled?

A4: The standard clamping force is 180 ± 30N.

Reason: Unstable clamping force causes uneven compression of paper and gaps between the sample and rubber gasket, leading to lateral air leakage. Fixed clamping force minimizes operator error and ensures repeatable, comparable test data across labs.

Q5: What are the specifications for the rubber gasket of the Gurley fixture?

A5: Hardness: 50 IRHD (compliant with ISO 48)

Thickness: 0.7 mm–1.0 mm

Inner diameter: 28.6 ± 0.1 mm (forms 642 mm² standard test area)

Material: Smooth, oil-resistant, non-oxidizing elastic rubber.

It prevents edge air leakage between the paper specimen and clamping plates.

Q6: How to handle extremely dense (low permeability) paper and highly porous paper during timing?

A6: Dense paper/board: Timing can stop after the first 50 mL mark, then convert the recorded time to an equivalent 100 mL value for calculation.

Highly porous paper: Measure a larger air volume than 100 mL, then normalize the time to 100 mL to reduce timing error.

If stable cylinder movement only appears after the 50 mL scale, start timing at the 50 mL mark.

Q7: Why is vibration forbidden during the Gurley test?

A7: Vibration accelerates the sinking speed of the inner floating cylinder, which shortens the recorded time and falsely increases calculated air permeance, resulting in inaccurate test results.

Q8: Why is the ISO 5636-5 Gurley test important for paper and board manufacturers?

A8: It quantitatively characterizes paper internal pore structure and fiber compactness, which cannot be judged visually.

Permeance directly predicts critical end-use performance:

Low permeance = dense barrier paper for food packaging, oil-proof wrapping;

High permeance = breathable filter paper, tea bag paper, absorbent printing paper.

Real-time production control: It monitors pulp beating, coating uniformity, sizing efficiency and calendering pressure.

Standardized test data enables consistent product specifications, batch acceptance and cross-factory quality comparison.

Most paper purchasing contracts specify ISO 5636-5 Gurley permeance as a mandatory acceptance index to avoid quality disputes.

Q9: What problems can inconsistent Gurley air permeance cause for finished paper products?

A9: Printing paper: Overly high permeance causes excessive ink absorption and fuzzy print dots; overly low permeance leads to slow ink drying and smudging.

Food packaging: Too high permeance fails oxygen/oil barrier requirements and shortens food shelf life; too low permeance blocks breathability for fresh produce packaging.

Filter/tea bag paper: Abnormal permeance disrupts filtration efficiency and liquid flow speed.

Coated paper: Uneven permeance indicates inconsistent coating thickness, resulting in uneven gloss and barrier performance.

Q10: My test results show high data fluctuation between replicates. What are the common root causes per ISO 5636-5?

A10: Unstable clamping force (not controlled at 180±30 N)

Damaged, deformed or improperly installed rubber gasket causing air leakage

Vibration transmitted to the testing bench during timing

Specimens with creases, holes or uneven surface

Specimens not fully conditioned per ISO 187 standard atmosphere

Leakage of sealing oil or oil viscosity out of specification range

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