How do you translate ISO 5636-5:2013 Gurley air-permeance and air-resistance test reports when a paper mill lists seconds per 100 mL, air resistance, µm/(Pa·s), different paper grades and laboratory qualification notes? Paper producers, packaging engineers, procurement specialists and translation teams need the numbers to retain their physical meaning. Confusing air resistance with air permeance can make the same value sound as though airflow has increased when the relevant measure suggests the opposite.
This guide answers the focused search intent for Gurley seconds translation, ISO 5636-5 paper air permeance, air resistance s/100 mL, paperboard permeability terminology and Gurley laboratory report interpretation. It protects definitions, units, measured versus calculated quantities, specimen identity, sample limitations and release decisions. It does not replace the copyrighted test method, prescribe apparatus operation or provide an unsupported conversion calculator.
The ISO publication record identifies ISO 5636-5:2013 as the published Gurley method for paper and board air permeance, confirmed in 2024. The catalogue gives an intended permeance range of 0.1 to 100 µm/(Pa·s) and warns that rough specimens that cannot be clamped without leakage are unsuitable. Those are questions of method scope, not decorative footnotes. A trustworthy translation preserves them.
Two opposite-looking results can both describe the same sheet
Imagine that a report gives one paper grade a longer Gurley time than another. When the measurement basis is comparable, the longer resistance time reflects slower passage of a specified air volume rather than an increase in air throughput. Another report could instead use air permeance as its outcome. If the translator combines these columns under one generic ‘porosity’ label, the buyer may infer precisely the wrong performance direction.
The evidence chain runs from sheet type and condition to apparatus, differential pressure, exposed area, air volume, elapsed time, property and report conclusion. Here are thirty practical translation decisions that protect that chain. They are explanations of report meaning, not operating instructions for a testing laboratory.
Learn the exact property before translating its units
1. Gurley method identity
ISO 5636-5:2013 concerns air permeance and air resistance of paper and board using a Gurley air-resistance apparatus. Check the exact standard part and edition cited in the laboratory report before translating its numerical table. A reader should be able to reconstruct the intended property from the technical words before drawing a comparison.
Calling the method a general breathability test can hide the defined paper-sheet property. Name the paper and board Gurley method explicitly. The essential translation check is to write the reported property above the column before copying the number. Then verify the sample, unit and source method. This simple sequence prevents an elegant target-language sentence from describing a physically different variable.
2. Air permeance meaning
Air permeance relates flow of air through a sheet to area and pressure difference under specified measurement conditions. Preserve the property name and the reporting units that accompany the laboratory’s declared value. A reader should be able to reconstruct the intended property from the technical words before drawing a comparison.
Replacing permeance with porosity suggests a different measurement and may mislead a buyer. Describe it as the measured sheet response to airflow, not the volume fraction of pores. A material engineer and a purchasing colleague might read the same table for different reasons. The engineer needs a reproducible measurement description; the purchaser needs to know what can reasonably be compared. Clear translation should serve both without turning laboratory evidence into a product warranty.
3. Air resistance meaning
Air resistance concerns the time associated with a specified volume of air crossing the measured sheet under the method. Keep the time figure, associated volume and instrument context together in the result. A reader should be able to reconstruct the intended property from the technical words before drawing a comparison.
A high air-resistance time must not be marketed as a high air-flow rate. Name resistance separately from permeance and state which variable the report actually displays. Try explaining the line without abbreviations: what crosses the specimen, what drives the motion, what is measured and what is calculated? If the explanation cannot answer these questions, return to the source rather than choosing a plausible generic term.
4. Opposite directions
Greater resistance time generally means air passes less readily under comparable conditions, unlike a larger permeance value. Preserve the result type before interpreting whether a higher number indicates more or less airflow. A reader should be able to reconstruct the intended property from the technical words before drawing a comparison.
Copying the word greater into a sentence about permeance can reverse the practical conclusion. Read the units first, then describe the direction of the relationship. In a bilingual report, the original and translation should permit a row-by-row audit. A reader must not guess which value belongs to which specimen, whether a number is raw or derived, or whether it is an acceptance limit rather than an observed result.
5. Seconds per 100 mL
Reports may present Gurley air resistance using time per defined volume, commonly seconds per 100 millilitres. Keep s per 100 mL notation and any source-defined alternative reporting volume visible in the translated table. A reader should be able to reconstruct the intended property from the technical words before drawing a comparison.
Turning seconds per 100 millilitres into seconds per litre without conversion changes magnitude. Retain the denominator and calculate only where a documented basis permits. The absence of a source fact must remain visible. A translator cannot responsibly supply an unrecorded pressure, sample area, handling condition or calculation merely to make the document read smoothly. Ask the issuing laboratory when the distinction affects interpretation.
Protect apparatus, airflow and measurement basis
6. Micrometres per pascal-second
The standard uses micrometres per pascal-second as a unit of air permeance in the specified sheet context. Preserve the symbol µm/(Pa·s) with the numerator and denominator in the correct order. A reader should be able to reconstruct the intended property from the technical words before drawing a comparison.
Replacing it with micrometres of physical thickness invents a dimension not being measured. Add a plain-language definition outside the official result cell. One common mistake is treating every larger number as more of the same performance. For this method, time and flow can point in opposite directions. Begin with the dimension and the specified measurement basis before making any qualitative statement about a paper grade.
7. Permeance versus permeability
Permeance describes the sheet property and does not normalize the result by material thickness in the same way as intrinsic permeability. Record whether the report says permeance, permeability or resistance, without conflating the labels. A reader should be able to reconstruct the intended property from the technical words before drawing a comparison.
A translator who substitutes permeability may claim a thickness-independent property the test did not report. Use the method’s specific technical noun and explain why thickness still matters to product context. The essential translation check is to write the reported property above the column before copying the number. Then verify the sample, unit and source method. This simple sequence prevents an elegant target-language sentence from describing a physically different variable.
8. Paper versus board
This method can apply to suitable paper and board samples, not arbitrary industrial membranes without checking the method scope. Keep grammage, board grade, paper type, coating description and sample identity where supplied. A reader should be able to reconstruct the intended property from the technical words before drawing a comparison.
Rendering every specimen simply as packaging gives no clue which material layer was tested. Preserve substrate terms and manufacturing variant codes. A material engineer and a purchasing colleague might read the same table for different reasons. The engineer needs a reproducible measurement description; the purchaser needs to know what can reasonably be compared. Clear translation should serve both without turning laboratory evidence into a product warranty.
9. Applicable measurement range
ISO’s catalogue describes a Gurley applicability range of 0.1 to 100 µm/(Pa·s) for air permeance. Preserve any reported limitation, out-of-range statement or alternate method recommendation from the laboratory. A reader should be able to reconstruct the intended property from the technical words before drawing a comparison.
An out-of-range value should not be represented as an ordinary precise measurement. Keep the method limitation visible and ask the issuer for the appropriate report. Try explaining the line without abbreviations: what crosses the specimen, what drives the motion, what is measured and what is calculated? If the explanation cannot answer these questions, return to the source rather than choosing a plausible generic term.
10. Rough-surface limitation
Rough or irregular paper surfaces can prevent a secure seal in the clamping assembly. Retain specimen-surface notes and any statement that leakage could invalidate the reading. A reader should be able to reconstruct the intended property from the technical words before drawing a comparison.
Presenting a compromised measurement as fully valid can mislead product qualification. State that clamping or leakage limitations require laboratory evaluation, not translator repair. In a bilingual report, the original and translation should permit a row-by-row audit. A reader must not guess which value belongs to which specimen, whether a number is raw or derived, or whether it is an acceptance limit rather than an observed result.
Follow specimen preparation and repeatability
11. Gurley apparatus
The apparatus is the identified type of air-resistance tester used for this method. Preserve the equipment name, calibration or verification identifier and apparatus version as actually reported. A reader should be able to reconstruct the intended property from the technical words before drawing a comparison.
Replacing the instrument with an unspecified airflow meter makes it harder to compare methods. Use Gurley apparatus consistently rather than a casual generic description. The absence of a source fact must remain visible. A translator cannot responsibly supply an unrecorded pressure, sample area, handling condition or calculation merely to make the document read smoothly. Ask the issuing laboratory when the distinction affects interpretation.
12. Test principle
The measured event concerns air passing through a clamped sheet under the apparatus’s controlled pressure difference. Keep measurement-time and airflow language separate from pressure or specimen-area settings. A reader should be able to reconstruct the intended property from the technical words before drawing a comparison.
Describing air flowing freely around a sheet reverses the meaning of a through-sheet measurement. Explain that the relevant path is across the specimen’s exposed area. One common mistake is treating every larger number as more of the same performance. For this method, time and flow can point in opposite directions. Begin with the dimension and the specified measurement basis before making any qualitative statement about a paper grade.
13. Test area
The measured sheet area is part of the basis for relating flow and pressure to air permeance. Preserve stated area and any actual alternative measurement opening recorded by the laboratory. A reader should be able to reconstruct the intended property from the technical words before drawing a comparison.
Changing square centimetres into centimetres loses a dimension and can affect calculated values. Keep area units explicit and check any conversion independently. The essential translation check is to write the reported property above the column before copying the number. Then verify the sample, unit and source method. This simple sequence prevents an elegant target-language sentence from describing a physically different variable.
14. Pressure difference
Air permeance relates to pressure difference through the sheet rather than atmospheric pressure alone. Retain the actual differential-pressure notation and source status where present. A reader should be able to reconstruct the intended property from the technical words before drawing a comparison.
Writing a pressure setpoint as an observed air-permeance result mixes two distinct quantities. Separate driving pressure from calculated or measured flow response. A material engineer and a purchasing colleague might read the same table for different reasons. The engineer needs a reproducible measurement description; the purchaser needs to know what can reasonably be compared. Clear translation should serve both without turning laboratory evidence into a product warranty.
15. Air volume
A specified displaced air volume may form the basis of the Gurley timing result. Record the exact volume, its unit and the method-specific reporting convention in bilingual tables. A reader should be able to reconstruct the intended property from the technical words before drawing a comparison.
Deleting the volume makes two times expressed in seconds appear comparable when their denominators may differ. Keep volume associated with every resistance figure. Try explaining the line without abbreviations: what crosses the specimen, what drives the motion, what is measured and what is calculated? If the explanation cannot answer these questions, return to the source rather than choosing a plausible generic term.
Keep calculations, exclusions and comparisons honest
16. Elapsed time
Timing is an observed component, whereas permeance is a derived or reported sheet property. Preserve raw times separately from any mean, converted unit or computed result. A reader should be able to reconstruct the intended property from the technical words before drawing a comparison.
A translator who labels a measured duration as a rate has inverted time and flow. Give elapsed time and the reported derived measure their own labels. In a bilingual report, the original and translation should permit a row-by-row audit. A reader must not guess which value belongs to which specimen, whether a number is raw or derived, or whether it is an acceptance limit rather than an observed result.
17. Clamping and seal
Proper specimen sealing matters because air should pass through the test portion rather than around its edge. Preserve any documented leak checks, clamp limitations and rejected runs. A reader should be able to reconstruct the intended property from the technical words before drawing a comparison.
Ignoring a leakage warning can make a false high-airflow interpretation seem authoritative. Report the laboratory qualification without attempting to correct the measurement mathematically. The absence of a source fact must remain visible. A translator cannot responsibly supply an unrecorded pressure, sample area, handling condition or calculation merely to make the document read smoothly. Ask the issuing laboratory when the distinction affects interpretation.
18. Sample preparation
Cutting, handling and preparation can affect a sheet’s edges, flatness and ability to clamp. Keep preparation notes and sample codes alongside reported measurements. A reader should be able to reconstruct the intended property from the technical words before drawing a comparison.
Treating a torn or creased specimen as an untouched production sample obscures a possible influence. Preserve the condition of the material as tested. One common mistake is treating every larger number as more of the same performance. For this method, time and flow can point in opposite directions. Begin with the dimension and the specified measurement basis before making any qualitative statement about a paper grade.
19. Conditioning atmosphere
Paper responds to moisture, so conditioning information can be essential when interpreting the property. Retain declared conditioning atmosphere, timing and deviations if the laboratory recorded them. A reader should be able to reconstruct the intended property from the technical words before drawing a comparison.
A translated result with environmental context deleted may look more universal than the source. Put environmental information in a labelled evidence section. The essential translation check is to write the reported property above the column before copying the number. Then verify the sample, unit and source method. This simple sequence prevents an elegant target-language sentence from describing a physically different variable.
20. Coatings and laminates
A barrier coating or laminated layer can substantially change air-flow behaviour compared with an uncoated paper sheet. Preserve coating side, layer structure and product designation when included in the source report. A reader should be able to reconstruct the intended property from the technical words before drawing a comparison.
Transferring one result to the uncoated base stock misidentifies the specimen. Keep material stack and finish description attached to each result. A material engineer and a purchasing colleague might read the same table for different reasons. The engineer needs a reproducible measurement description; the purchaser needs to know what can reasonably be compared. Clear translation should serve both without turning laboratory evidence into a product warranty.
Distinguish unrelated barriers and specifications
21. Machine and cross directions
Machine direction and cross direction are distinct sheet orientation labels and should remain intact when used. Keep MD and CD codes in the reported notes, even if the test interpretation requires additional context. A reader should be able to reconstruct the intended property from the technical words before drawing a comparison.
Expanding MD as medical doctor or deleting CD may corrupt production traceability. Define manufacturing-direction abbreviations explicitly. Try explaining the line without abbreviations: what crosses the specimen, what drives the motion, what is measured and what is calculated? If the explanation cannot answer these questions, return to the source rather than choosing a plausible generic term.
22. Repeat measurements
Multiple readings from one product sample provide evidence about local variation and repeatability. Preserve individual runs, accepted and rejected values, averages and the stated reduction rule. A reader should be able to reconstruct the intended property from the technical words before drawing a comparison.
Quoting only the best time creates a misleading comparison between paper grades. Keep the reported statistical method rather than inventing an alternative average. In a bilingual report, the original and translation should permit a row-by-row audit. A reader must not guess which value belongs to which specimen, whether a number is raw or derived, or whether it is an acceptance limit rather than an observed result.
23. Reported mean
An average result belongs to a stated set of observations, unit and possible rounding procedure. Preserve the raw range, mean label and any uncertainty statement available in the record. A reader should be able to reconstruct the intended property from the technical words before drawing a comparison.
An averaged air-resistance time is not the same data object as a converted air-permeance average. Label aggregation and transformation distinctly. The absence of a source fact must remain visible. A translator cannot responsibly supply an unrecorded pressure, sample area, handling condition or calculation merely to make the document read smoothly. Ask the issuing laboratory when the distinction affects interpretation.
24. Outlier and invalid run
A report may exclude a run for a documented leak, surface problem or instrument issue. Keep exclusions and reasons as source facts instead of quietly discarding them. A reader should be able to reconstruct the intended property from the technical words before drawing a comparison.
A translated table showing only retained results may conceal why a measurement was judged invalid. Preserve the exception trail for review. One common mistake is treating every larger number as more of the same performance. For this method, time and flow can point in opposite directions. Begin with the dimension and the specified measurement basis before making any qualitative statement about a paper grade.
25. Decimal and separator conventions
Thousands separators, decimal commas and unit symbols can shift when records are localized. Check all numerical cells against the original, including ranges, zeros and less-than qualifiers. A reader should be able to reconstruct the intended property from the technical words before drawing a comparison.
A misplaced decimal point can change a Gurley time or permeance value by an order of magnitude. Use a documented numeric localization policy and independent check. The essential translation check is to write the reported property above the column before copying the number. Then verify the sample, unit and source method. This simple sequence prevents an elegant target-language sentence from describing a physically different variable.
Build a traceable bilingual technical report
26. Alternate airflow methods
Other methods such as Bendtsen or Sheffield may assess different ranges or use different instruments and reporting conventions. Keep the declared instrument and method with each value rather than treating all air-flow numbers as identical. A reader should be able to reconstruct the intended property from the technical words before drawing a comparison.
A Gurley seconds figure should not be compared directly with another method’s native scale. Request method-compatible data or a documented conversion basis. A material engineer and a purchasing colleague might read the same table for different reasons. The engineer needs a reproducible measurement description; the purchaser needs to know what can reasonably be compared. Clear translation should serve both without turning laboratory evidence into a product warranty.
27. Air versus water barrier
Air permeance is not proof of resistance to liquid water, water vapour or chemical migration. Preserve separate Cobb, vapour transmission and barrier tests as independent properties. A reader should be able to reconstruct the intended property from the technical words before drawing a comparison.
A low airflow number does not automatically mean waterproof paper or food-safe packaging. Describe the measured air-flow response and avoid unrelated claims. Try explaining the line without abbreviations: what crosses the specimen, what drives the motion, what is measured and what is calculated? If the explanation cannot answer these questions, return to the source rather than choosing a plausible generic term.
28. Packaging performance claims
Package designers may consider ventilation, printability or barrier needs, but Gurley evidence addresses one property. Keep the buyer’s requirement and any actual Gurley threshold separate from unrelated packaging promises. A reader should be able to reconstruct the intended property from the technical words before drawing a comparison.
Translating a laboratory value as total shelf-life protection broadens the source beyond its authority. State the property’s relevance without certifying product suitability. In a bilingual report, the original and translation should permit a row-by-row audit. A reader must not guess which value belongs to which specimen, whether a number is raw or derived, or whether it is an acceptance limit rather than an observed result.
29. Laboratory and report identity
Issuer, report number, date, sample intake details and authorized revision enable someone to trace the measurement. Keep those identifiers exactly as supplied and attribute values to the issuing laboratory. A reader should be able to reconstruct the intended property from the technical words before drawing a comparison.
A translated report that erases provenance can circulate as an unverified product claim. Attach the source issue and mark the translation separately. The absence of a source fact must remain visible. A translator cannot responsibly supply an unrecorded pressure, sample area, handling condition or calculation merely to make the document read smoothly. Ask the issuing laboratory when the distinction affects interpretation.
30. Final technical summary
A usable multilingual report says what paper was tested, which Gurley property was reported, in what units and under what limitations. Keep the specimen code, air-resistance time or permeance value, method citation and cautions together. A reader should be able to reconstruct the intended property from the technical words before drawing a comparison.
A final slogan such as fully breathable or airtight lacks the precision of the original evidence. Use a bounded summary and point readers back to the complete data table. One common mistake is treating every larger number as more of the same performance. For this method, time and flow can point in opposite directions. Begin with the dimension and the specified measurement basis before making any qualitative statement about a paper grade.
Five worked paper and packaging translation cases
One report lists 180 s/100 mL and another lists a permeance value
These are invented figures used to illustrate interpretation. The first expression identifies an air-resistance time under a specified volume basis; the other represents a different, flow-related property. Even when the same apparatus produced both, direct numeric comparison without the full method and conditions is unsound. Begin by translating the column titles accurately, preserving the units and confirming which property the laboratory intends.
Do not say that the first sample is 180 times less breathable or more porous. Such claims require a legitimate common basis and a meaningful performance question. If purchasing needs comparable results, ask the laboratory for a method-consistent comparison. Preserve the original source note and the distinction between a laboratory observation and a purchaser’s separate decision.
A paperboard sheet leaks around the clamp
The laboratory notes that the specimen’s rough surface prevented reliable sealing. The translator may be tempted to omit this sentence so the numbers look clean. That would hide a serious limitation: some observed airflow may not represent passage through the sheet. Preserve the note, identify the affected specimen and do not ‘correct’ the numerical value with a guessed factor.
The right buyer-facing explanation is that the reported test had an identified validity limitation requiring laboratory review. It is not a proof of enhanced permeability or defective material without further evidence. Preserve the original source note and the distinction between a laboratory observation and a purchaser’s separate decision.
A supplier promotes a low Gurley number as waterproof
A short air-resistance time may mean relatively ready air passage under comparable test conditions; it says nothing directly about resistance to water droplets, liquid absorption or water vapour. The supplier has moved from one measured property to another. Translate the actual air-resistance finding, then distinguish any separately documented water-barrier result.
For packaging design, avoid compressing airflow, water barrier and shelf-life claims into one vague quality rating. Each property needs its own applicable method, conditions, limit and evidence. Preserve the original source note and the distinction between a laboratory observation and a purchaser’s separate decision.
Two factories report Gurley and Sheffield results
The numerical figures look conveniently similar, but the instruments and conventions differ. Keep each test method in its own row. Do not call both values identical ‘air permeability’ merely to make a multilingual spreadsheet tidy. Request a valid comparison method from the technical owner if the purchasing decision depends on equivalence.
A readable glossary is helpful, but a glossary cannot make non-equivalent measurements interchangeable. The target-language chart should show the exact native unit and source method. Preserve the original source note and the distinction between a laboratory observation and a purchaser’s separate decision.
An updated laboratory file changes its mean
An earlier translation has a mean value, while a revised file excludes an invalid run and reports a different result. Find the source issue and revision, the raw results, the exclusion and the reported reduction rule. Only the laboratory should determine which run is valid. The translator can faithfully identify which version is current and state what changed.
Avoid keeping the old target-language summary alongside the new result without a superseded notice. The goal is controlled evidence rather than a visually perfect but outdated report. Preserve the original source note and the distinction between a laboratory observation and a purchaser’s separate decision.
Frequently asked questions
Is Gurley air resistance the same as air permeance?
No. They describe related but differently expressed properties. Resistance time and flow-related permeance must keep their own definitions, units and appropriate comparison basis. The safe short answer retains the measurement basis and does not treat a single material test as a guarantee for all packaging performance.
What does a result in seconds per 100 mL mean?
It is a time linked to a specified air volume in the method’s air-resistance convention. Preserve both time and volume; a naked number in seconds is incomplete. The safe short answer retains the measurement basis and does not treat a single material test as a guarantee for all packaging performance.
Is air permeance the same as permeability?
No. Air permeance is a sheet property under defined conditions and is not necessarily thickness-normalized as an intrinsic material permeability would be. The safe short answer retains the measurement basis and does not treat a single material test as a guarantee for all packaging performance.
Does a longer Gurley time mean more airflow?
Generally the opposite when comparing air-resistance results under the same valid conditions: more time for the specified air volume means slower passage. The safe short answer retains the measurement basis and does not treat a single material test as a guarantee for all packaging performance.
Can this test certify waterproof packaging?
No. Passing air through a sheet and resisting water or vapour are different material questions. Use separately relevant measurements for water barriers. The safe short answer retains the measurement basis and does not treat a single material test as a guarantee for all packaging performance.
What happens if the test specimen is too rough to clamp?
The published method identifies securely clamped specimens as important. Preserve any leakage or unsuitable-specimen statement instead of presenting a compromised reading as ordinary evidence. The safe short answer retains the measurement basis and does not treat a single material test as a guarantee for all packaging performance.
Can I compare Gurley and Bendtsen numbers directly?
Not merely by reading the digits. The apparatus, method, property and native units must first be reconciled by a technically valid basis. The safe short answer retains the measurement basis and does not treat a single material test as a guarantee for all packaging performance.
What makes the translation reliable?
Correct property labels, complete units, source and specimen identifiers, apparatus and condition notes, accepted and excluded runs, version control and qualified conclusions. The safe short answer retains the measurement basis and does not treat a single material test as a guarantee for all packaging performance.
Release workflow for a dependable translated Gurley report
First align every result with the material submitted and the instrument and measurement method named by the issuing laboratory. Create a bilingual column map: sample, conditioning, method, raw timing, volume basis, air-resistance unit, calculated or reported permeance, replicate information, exclusions and the laboratory’s own conclusion. Mark any fields absent from the source as absent; they are not invitations to fill gaps through assumption.
Second, test the direction of every translated comparison. Is the sentence about more elapsed time, greater air resistance or higher air permeance? These are not interchangeable. Check mathematical notation, decimal separators, denominators and positive or negative qualifiers. Where the source gives an alternative method or an explicit range limitation, retain it adjacent to the numerical result.
Third, review what the buyer is trying to decide. An envelope producer, filtration specialist or packaging team may want an airflow property for a particular design, but the laboratory report does not automatically authorize claims about water resistance, food contact, printability or longevity. Keep the test result bounded and direct the reader to other evidence when another property is actually being sought.
This narrow application links to the established Master Art of Translation reference, the Vocabulary Learning Hub for technical word distinctions and How English Works for evidence-led explanation. It does not replace those broader owners.