Oct 17, 2026Outdoor Materials & Components

How to Read a Bike Bag Fabric Test Report (and What It Won't Tell You)

Fabric test reports prove less than they seem. The five fields to check - method, sample, conditioning, threshold, lab - and what no report covers.

Short answer: a fabric test report proves what one lab measured on one sample under one method - not how your bag performs at the seams, in the sun, or under load. Read five fields before the headline number: method, sample, conditioning, threshold, and lab. Missing any of them, treat the number as marketing. Send us a report and we will read the five fields with you.
Most sourcing managers meet the fabric before they meet the product: a PDF with numbers, stamps and a signature. The numbers look objective - which is exactly why they are easy to misread.
This guide is for buyers comparing supplier reports, whether it is your first order or your tenth. It shows what a report proves, what it never covers, and the five fields that separate evidence from decoration.
Key takeaways
• A report is only valid for its method. ISO 811 (third-drop reading) and AATCC TM127 both measure hydrostatic head, but spray tests like AATCC TM22 score surface wetting only - and AWTA states a spray rating cannot predict water passing through the fabric.
• Method choice moves the number more than fabric choice. ACT reports that Wyzenbeek and Martindale results have no correlation, and the same fabric can vary by 60%+ across retests.
• “25,000 rubs” usually means the test stopped at 25,000. Martindale stops at two yarn breaks; a pass at 25,000 is not the same as surviving a 30,000-cycle run.
• The report never covers the finished seam. TUL measured unsealed stitched seams leaking at just under 100 cm of water pressure - about 20x below the intact fabric behind the same report.
• Test hours and cycles do not convert into years. ACT explicitly refuses that conversion for lightfastness (650 h outdoor benchmark) and hydrolysis (10-week outdoor threshold).
How we verified this
This is a standards-literacy guide, not a test run. Every number comes from published standards, lab method documents or industry technical guides: ISO, AATCC, AWTA, ACT, and a Technical University of Liberec seam study. Our own operating facts (sampling 7-12 days, production 45-55 days after approval) are labeled separately. No invented tests.
The five fields that decide whether a number means anything
Before reading any number, read the five fields around it. Each one can change the result by as much as the fabric itself.
• Method. Which standard, and which test type inside it? ISO 811 and AATCC TM127 both measure hydrostatic head. AATCC TM22 is a spray test that scores surface wetting 0-100. Same fabric, different question - and the answers are not interchangeable.
• Sample. Production roll, lab swatch, or a “best batch”? Ask for the batch ID and date. A report with no sample identity cannot be tied to your order.
• Conditioning. Textiles are conditioned before testing; the report should name the conditioning standard (ISO 139 for textiles). Wet, cold or unconditioned samples read differently.
• Threshold vs result. “>5,000 mm” is a pass/fail gate, not a measured ceiling. Ask for the actual value and the number of specimens.
• Lab and edition. Which lab (accredited to ISO/IEC 17025?), which edition of the standard, and when. An outdated edition is not evidence.
(Figure 1: The five fields - what each one changes. Chart pending upload; data listed above.)
What it means for importers: put these five fields into your RFQ template. Suppliers who can answer them are quoting evidence; suppliers who cannot are quoting adjectives.
What each common number actually measures
• Hydrostatic head (ISO 811 / AATCC TM127). The pressure the fabric resists before water passes, recorded at the third drop under ISO 811. It says nothing about seams, zippers or closures.
• Spray rating (AATCC TM22). Surface wetting on a 0-100 scale. Per AWTA, it cannot predict rain penetration - it does not test water passing through the fabric at all.
• Abrasion (Martindale ISO 12947 / Wyzenbeek ASTM D4157). Cycles before yarn breaks. ACT states the two methods do not correlate, retests of the same fabric can differ by 60%+, and the figure is not a lifespan.
• Lightfastness (ISO 105-B02 / AATCC TM16). Colour change graded against blue wool. ACT's outdoor benchmark is grade 4 at 650 test hours - and test hours are not service years.
• Hydrolysis (ISO 1419, tropical method C: 70°C at 95%+ RH). Coating resistance to damp heat. ACT thresholds: 5 weeks indoor, 10 weeks outdoor - with no year conversion.
• Coated-fabric minimums (ACT). Tongue tear ASTM D2261 at least 4x4 lbs, grab tensile ASTM D751 at least 50x50 lbs, flex ASTM D2097 through 25,000 cycles. These are contract-textile floors, not cargo-bike specs.
What it means for importers: compare numbers only inside one method and one sample definition. A “higher” number from a different method is not a better fabric - it is a different measurement.
Where every fabric report stops
A report tests flat goods. Your product is not flat goods.
• Seams. TUL measured unsealed stitched seams leaking at just under 100 cm; seam tape recovered 700-1,600 cm depending on construction; intact fabric measured 1,700-1,800 cm. One row of stitching costs roughly 20x water resistance - and no fabric report shows it.
• Ageing. An IJFTR outdoor year cut PU-coated nylon's air retention to unusable while tensile strength fell only 8.6%. The coating failed before the weave. ACT's hydrolysis guidance warns failures appear batch-wide, not unit by unit.
• Real loads. Abrasion happens where straps rub and hooks sit. A flat Martindale number does not move with your design.
(Figure 2: Fabric rating vs finished seam - the gap the report does not show. Chart pending upload; data listed above.)
What it means for importers: budget a seam check on the finished sample. It is the widest gap between the report and the product you will actually sell.
What we ask for when a report arrives
• The batch link: sample ID and date that match our order.
• Method and edition: ISO 811 or TM127 named, with the edition used.
• Actual values: the measured number and specimen count, not only ">".
• Seam evidence: a check on the finished sample, not just the roll - our sampling runs 7-12 days, and seams are tested there.
• Re-test on the approved sample: production then runs 45-55 days after approval and deposit.
What it means for importers: keep the batch-linked report in your project file. It becomes the baseline for every reorder and the first document you check when a complaint arrives.
Limitations
• This guide covers fabric-level reports; hardware such as buckles and zippers has separate standards.
• Standards are revised; always verify the edition named in the report.
• Lab results describe the tested sample; production consistency still needs incoming inspection.
• We are a bag factory, not a lab - our checks supplement, not replace, third-party reports.
FAQ
My supplier sent a 10,000 mm report. Is the cover waterproof?
The fabric may be. The product is not automatically. Seams, zippers and closures decide where water enters - TUL shows one row of stitching cuts resistance about 20x. Ask for seam construction and a finished-sample test.
Why do two labs give different Martindale results?
Because method choices and stopping rules differ, and ACT reports 60%+ variation on retests of the same fabric. Compare within one method, and treat a single number as indicative rather than absolute.
Does a higher hydrostatic number mean a longer-lasting cover?
No. Coating chemistry and ageing decide life. PU hydrolyses under damp heat, and an outdoor year can destroy air retention while tensile barely moves.
What should a complete report say about the sample?
Batch ID, sampling date, conditioning standard (ISO 139 for textiles), method edition, actual measured values and specimen count. Missing any of these, ask again.
Can I convert test hours into years of service?
No. ACT explicitly refuses that conversion for lightfastness and hydrolysis. Field exposure depends on climate, use and care.
Sending us a report to review - or building the next spec? Send the report with your drawing. We will check the five fields, flag what is missing, and quote the sampling plan. See how we run materials and QC at colorwaybag.com/bike-materials-and-qc, the cover leak check at colorwaybag.com/posts/how-to-check-cargo-bike-rain-cover-leaks, or contact us at colorwaybag.com/contact-us.
References
  1. ISO 811:2018 - Textiles, hydrostatic head test (third-drop reading). https://www.iso.org/standard/65149.html
  1. AATCC TM127 - Water resistance, hydrostatic pressure. https://members.aatcc.org/store/tm127/535/
  1. AATCC TM22 - Spray test, surface wetting rating 0-100. https://members.aatcc.org/store/tm22/487/
  1. AWTA - spray rating cannot predict water penetration. https://awtaproducttesting.com.au/app/documents/Water%20Repellency%20-%20Spray%20Rating%20(T29C).pdf
  1. Technical University of Liberec - seam sealing study (stitched vs taped water resistance). https://dspace.tul.cz/server/api/core/bitstreams/ddbb36cd-393d-40f7-a44c-809313f60bb2/content
  1. ACT - hydrolysis education guide (ISO 1419 thresholds; batch-wide failure). https://www.contracttextiles.org/wp-content/uploads/2022/08/act_hydrolysis_education_081222.pdf
  1. ACT - Association for Contract Textiles, coated fabrics guidance (abrasion correlation, lightfastness benchmarks). https://www.contracttextiles.org/
  1. Martindale method notes - test stops at two yarn breaks. https://kothea.com/
  1. S K Pal et al. (2011) - outdoor exposure study, Indian Journal of Fibre & Textile Research, Vol. 36, pp. 145-151. nopr.niscpr.res.in
  1. colorwaybag.com - materials and QC process (in-house checks, lab-tested options). colorwaybag.com/bike-materials-and-qc
  1. colorwaybag.com - cargo bike rain cover leak check (finished-sample seam test). colorwaybag.com/posts/how-to-check-cargo-bike-rain-cover-leaks