Waterproof and Breathable Performance Targets by Use: Which Figure Binds, and Where
For fabric development, sourcing and product teams Prepared by the Technical Department, Suzhou TTK Textile Technology Group Co., Ltd. The standard numbers below come from TTK's commissioned testing scope; the process statements come from TTK's own capability record.
Bottom line
"How high can it go" is the wrong question: the target is set by the end use, and over-delivering on one figure is usually paid for on another.
1. Five figures make up a waterproof and breathable specification
A waterproof and breathable clause is not one number. It is a set of figures, each read by its own test, and each capable of being the binding one:
| Figure | Standard in this scope | Unit | What it decides |
|---|---|---|---|
| Water resistance | GB/T 4744, ISO 811, AATCC 127 | mmH₂O or kPa | Whether liquid water is held out under pressure |
| Repellency | AATCC 22 (points), ISO 4920 and GB/T 4745 (grades) | points or grade | Whether the surface sheds water and stays dry-feeling |
| Moisture vapour transmission | GB/T 12704.2-B is the inverted-cup clause used for a waterproof-and-breathable construction; GB/T 12704.1 and GB/T 12704.2-A also sit in the scope, as do JIS L1099-B1 and ASTM E96 | g/m²·24h | How much vapour leaves the body |
| Air permeability | GB/T 5453, ISO 9237 | as specified by the standard | Wind resistance, and down-proofing behaviour |
| Peel strength | FZ/T 01010 | N/25mm or N/cm | Whether the laminated build stays together, including after washing |
Mass per unit area, verified under GB/T 4669, sits beside these as the figure that moves every time a layer or a pick-up changes.
A specification that names only one of these five has not specified a waterproof and breathable fabric. It has specified one property and left the rest to the supplier's judgement.
2. Which figure binds, by end use
The binding figure is the one the programme cannot sacrifice, and it changes with the use:
| End use | Binding figure | Second figure that constrains the build | Structure that usually fits |
|---|---|---|---|
| Urban and commuter rainwear | Repellency — the surface has to shed water through a walk to the station | Water resistance | 2L with a separate garment liner, or 2.5L where the shell is worn liner-free |
| Light hiking and travel shells | Water resistance and transmission together, since the wearer both walks and stops | Peel, as the build is carried in a pack | 2L or 2.5L |
| Alpine and ski shells | Peel after the named wash tier, because the garment is used hard and washed | Water resistance, and abrasion behaviour on the inside surface | 3L, usually with a detachable liner variant |
| Down jacket shell fabric | Down-proofing, read under GB/T 14272 and GB/T 12705.1 | Air permeability under GB/T 5453 or ISO 9237, and a light water resistance | Light coating or a light membrane build |
| High-exertion and cycling programmes | Transmission — the garment is chosen for what it lets out | Air permeability | Coating-led builds, or a breathable laminate kept thin |
| Workwear and general outdoor trousers | Repellency and wash durability | Peel and mass | Coating-led build, or a light 2L |
| Midlayers and liners | Transmission | Mass | Coating-led or knit-based build |
The row that surprises buyers most is the down jacket row. Down-proofing and air permeability pull against each other: a construction tight enough to stop down leaking is also tighter to air. On a down programme the two clauses have to be written together and tested together, under GB/T 14272 and GB/T 12705.1 on one side and GB/T 5453 or ISO 9237 on the other.
3. Why one figure cannot be raised on its own
| If you push… | Something else moves | Because |
|---|---|---|
| Repellency up | Handfeel stiffens | Stronger repellency usually means more add-on and more crosslinking on the face fabric |
| Water resistance up on a film build | Transmission falls | A thicker or more continuous film holds water out better and passes vapour more slowly |
| Transmission up | Water resistance becomes harder to hold | The paths that let vapour out are the same paths that let water in |
| Down-proofing up | Air permeability falls | A tighter structure resists airflow as well as down migration |
| Peel strength up | Handfeel stiffens and mass may rise | More adhesive and a heavier lamination pass buy the bond |
| Layer count up | Mass rises and drape falls | Each layer adds mass and each bonded interface adds stiffness |
This is why the specification has to say which figure is binding. When two clauses pull against each other, the supplier will satisfy the one that is measured and written down, and quietly land wherever it can on the other.
4. What "high" actually looks like, with the limits stated
Water resistance claims are the easiest to overstate, so it is worth separating two questions that buyers ask in one sentence: what is achievable, and what is stable.
One measured case from TTK's test records is worth quoting, with its limits attached:
``text Model: TTK232197BM-03 Hydrostatic pressure: as-received 18,500 mmH₂O (average of a specimen set) after 3 washes 18,990 mmH₂O Standard requirement: ≥ 15,000 mmH₂O ``
The post-wash figure is above the as-received figure. On this type of coating system that is not a data error: washing removes part of the auxiliary chemistry in the coating, the coating structure becomes denser, and fibre shrinkage closes pores at the same time.
The limits have to be stated with the same emphasis as the figure:
- This is a measured result on one specific model from one specific batch — it does not represent all TTK products, and it does not mean every colour and every batch reaches it.
- It must not be generalised into "water resistance does not fall after washing". That statement cannot be supported, and the honest position is the opposite: post-wash loss is a real risk, and the process has to be got right to avoid it.
- The number to design to is the customer's specification, not this case. Use the case to show that a post-wash decline is not inevitable, not as a target.
And on the transmission side: no generic figure is offered here. The transmission target has to come from the end use and the brand's own specification, because the figure depends on the method as much as on the fabric — GB/T 12704.1, GB/T 12704.2-A, GB/T 12704.2-B, JIS L1099-B1 and ASTM E96 are different methods and are not interchangeable. For a waterproof-and-breathable construction the inverted-cup method GB/T 12704.2-B is the usual clause.
5. How to write the target so it can actually be enforced
Write every clause in six parts, and the argument at bulk stage disappears:
- The property — water resistance, repellency, transmission, air permeability or peel.
- The standard number — GB/T 4744, ISO 811, AATCC 127, AATCC 22, ISO 4920, GB/T 4745, GB/T 12704.2-B, GB/T 5453, ISO 9237 or FZ/T 01010.
- The unit — mmH₂O or kPa, points or grade, g/m²·24h, or the unit the peel standard specifies.
- The wash tier and the washing standard for any post-wash figure — a tier such as 5, 10 or 20 washes, with GB/T 8629, ISO 6330 or AATCC 135 named beside it.
- The specimen rule — how many specimens, and whether the reported figure is the average or the worst specimen.
- The ramp rate or method note where the standard allows a choice — ISO 811 permits a selectable ramp rate, and the same fabric reports differently at different rates.
The ramp-rate item is the one most often left out. ISO 811 allows the laboratory to select the rate, and the same fabric can report a materially different figure at a different rate. Put the rate in the contract, not just the standard number.
6. Common pitfalls
| Pitfall | What it looks like | Cause |
|---|---|---|
| One number specified for a whole programme | The specification says "waterproof and breathable" with a single figure | Four of the five figures were left to the supplier |
| A target copied from another end use | Alpine-grade targets on commuter rainwear, and the cost lands on the buyer | The binding figure was not identified for the actual use |
| A post-wash figure with no tier or washing standard | The report says "after wash" | GB/T 8629, ISO 6330 and AATCC 135 differ, and every tier differs |
| A transmission figure with no method | Two suppliers disagree about the same membrane | GB/T 12704.1, GB/T 12704.2-A, GB/T 12704.2-B, JIS L1099-B1 and ASTM E96 are not interchangeable |
| A hydrostatic figure with no ramp rate | Sample passes and bulk fails under a different rate | ISO 811 permits a selectable rate |
| Down-proofing written without an air permeability clause | The shell holds the down and the garment is clammy | The two clauses pull against each other and both have to be written |
| A single case figure turned into a product promise | A marketing sentence claims no post-wash loss at all | One model from one batch was generalised into a product-wide claim |
| Repellency read on the as-received swatch only | The buyer reports a drop after the named wash tier | The tier and the washing standard were never tested |
7. Working order for a development programme
- Fix the end use and the wearing situation, not the headline figure.
- Name the binding figure for that use, and the second figure that constrains the build.
- Write all five clauses with standard, unit, tier, washing standard, specimen rule and ramp rate where they apply.
- Choose the structure against the mass and drape the programme can carry — layer count is a weight decision as much as a performance one.
- Test the binding figure post-wash at sample stage, at the tier you intend to claim.
- State the limits of any quoted case figure, including the model, the batch and the washing condition, so it cannot be read as a product-wide promise.
- Keep retained samples per lot and per article, so a bulk argument has a reference to be settled against.
Criteria Table: How to Tell Whether a Waterproof and Breathable Target Is Written Properly
| Criterion | What Passing Looks Like | Common Failure |
|---|---|---|
| The binding figure for the end use is named | The specification says which of water resistance, repellency, transmission, air permeability or peel is the binding requirement | A single figure is applied to every programme, and the wrong property is optimised |
| More than one figure is specified | The specification carries the whole set of figures the end use needs | "Waterproof and breathable" stands in for a specification, and four figures are left to the supplier |
| The water resistance standard is named | The clause names GB/T 4744, ISO 811 or AATCC 127 | A hydrostatic figure appears with no standard and cannot be compared |
| The ramp rate is fixed in writing | The clause states which ramp rate applies where the standard permits a choice | Sample and bulk are judged at different rates, and the same fabric reports differently |
| The repellency clause carries its scale | The clause names AATCC 22 in points or ISO 4920 and GB/T 4745 in grades, with the unit printed | A figure is quoted with no scale, so a points result and a grade result are treated as one |
| The transmission clause names the method and the unit | The clause names GB/T 12704.2-B for a waterproof-and-breathable construction, with the figure in g/m²·24h | GB/T 12704.1, GB/T 12704.2-A, GB/T 12704.2-B, JIS L1099-B1 and ASTM E96 figures are compared as equivalent |
| The air permeability clause exists where the end use needs it | The clause names GB/T 5453 or ISO 9237 | Wind resistance or down-proofing is assumed to follow from the build |
| Down-proofing and air permeability are written together | A down programme carries GB/T 14272 and GB/T 12705.1 alongside GB/T 5453 or ISO 9237 | One is written and the other is discovered at complaint stage |
| The peel clause carries a tier and a washing standard | Peel is required under FZ/T 01010 after a named tier and under GB/T 8629, ISO 6330 or AATCC 135 | An as-received peel figure stands in for the laminated article's behaviour |
| The specimen and averaging rule are agreed | The clause states how many specimens are tested and whether the average or the worst specimen is reported | The average passes and the bulk is rejected on the worst specimen |
| Mass per unit area is part of the clause set | Mass is written and verified under GB/T 4669 | Layer and pick-up changes move mass, and the delivered article misses the approved sample |
| Any quoted case figure carries its limits | A measured case is presented with its model, its batch and its washing condition, and explicitly not as a product-wide promise | A single case is generalised into a claim that no post-wash loss occurs |
Related Reading
- Fluorine-Free Water Repellency: Wash Durability and Handfeel Judged Together — companion article, the repellency half of the same specification
- Two-Layer and Three-Layer Lamination Structures: What Each Layer Is Doing — companion article, choosing the build against mass and drape
- Hydrostatic Pressure Testing: Five Standards, Ramp Rates and Post-Wash Retention — existing article, how the water resistance clause has to be written (draft
content/drafts/en/01-hydrostatic-pressure-guide.en.md) - Moisture Vapour Transmission Testing: GB/T 12704, ASTM E96 and JIS L1099 Compared — existing article, why the method has to be named (draft
content/drafts/en/03-mvtr-testing-guide.en.md) - Lamination — process page, where the membrane or coating that sets the water resistance figure is bonded into the build
- Process Comparison — process page, how the coating and lamination routes compare for a given target
- Product Guides — Resource Section — section page
Suzhou Tutaike Textile Technology Group Co., Ltd. (formerly Wujiang Tutaike Textile Finishing Co., Ltd.) Website: https://www.szttk.com.cn