Fluorine-Free Water Repellency: Wash Durability and Handfeel, Judged Together
For fabric development and sourcing 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
Fluorine-free water repellency is not one claim but two: how much spray rating survives which wash tier, and how much the finish changed the hand.
1. "Fluorine-free" is a route, not an acceptance standard
The acceptance test does not change when the chemistry changes. Spray rating is still read under AATCC 22 (points), ISO 4920 (grade) or GB/T 4745 (grade). Domestic orders usually name GB/T 4745, European orders ISO 4920, North American orders AATCC 22.
What changes is the chemistry behind the finish:
| Route | Chemistry family | Where it is strong | Where it is limited |
|---|---|---|---|
| C0 fluorine-free | Silicone, polyurethane, bio-inspired systems | Fits markets that restrict fluorinated chemistry; generally a softer hand | Oil repellency is weaker than fluorinated systems; wash durability depends on crosslinking rather than on the chemistry alone |
| C6 fluorinated | Short-chain fluorocarbon | High initial water and oil repellency, good wash durability | Still a fluorinated chemistry, so it does not answer a fluorine-free requirement |
| C8 fluorinated | Long-chain fluorocarbon | Strongest repellency of the three | No longer the direction of the mainstream market |
So "we use fluorine-free" answers a compliance question. It does not answer the two questions a brand will actually test: after how many washes, and at what grade.
Note on the compliance half of the question: the EN 17681-1:2025 substance list sits in TTK's commissioned testing scope, which means results can be issued against it. This article does not report results against that list, and no absolute statement such as "contains none" is made anywhere below.
2. Durability is a curve, and the wash tier has to be named
"Wash resistant" on its own says nothing, because every finish survives one wash. What separates suppliers is which tier the claim is made at, and which washing standard produced the tier.
| Wash tier | What it is used for | Who normally asks for it |
|---|---|---|
| As-received | Factory acceptance on the sample | All orders |
| After 1–5 washes | Light use, single-event activity wear | Low- to mid-tier programmes |
| After 6–10 washes | Standard outdoor apparel | Most outdoor shells |
| After 11–15 washes | Frequent use, professional outdoor | Higher-tier programmes |
| After 20 or more washes | Durability claims carried in brand marketing | Brands that write wash counts into the spec |
Three washing standards are used for the post-wash figure, and they do not apply the same mechanical action:
- GB/T 8629 — domestic orders, the most common route
- ISO 6330 — European orders
- AATCC 135 — North American orders
The count without the standard is an incomplete claim. "Washes 20 times" means nothing if the washing standard is not named beside it, because the tier and the standard together define what was actually tested.
TTK's fluorine-free route corresponds to the item written in the testing scope as a durable wash-resistant repellent, withstands 20+ washes. That is a scope statement about what the finishing route is built to carry, not a promise that every colour and every batch reaches the same figure. The tier that matters is the one on the report for the specific article.
3. Why C0 durability has to be built, not assumed
Fluorinated systems hold repellency partly through the ordered arrangement of long fluorinated chains on the fibre surface. A fluorine-free system does not have that, so durability has to come from fixing the finish to the fibre by reaction:
| Lever | What it does | What happens when it is wrong |
|---|---|---|
| Crosslinker | A blocked isocyanate crosslinker anchors the repellent to the fibre instead of leaving it sitting on the surface | Without crosslinking the finish washes off very easily, and the drop in spray rating appears by the first few washes |
| Curing temperature and time | Drives the crosslinking reaction to completion | Under-curing leaves the reaction incomplete; the finish looks good as-received and fails after washing |
| Fabric preparation | Clean surface, controlled pH, no interfering residual auxiliaries | Residuals consume the crosslinker or block the reaction, so the same recipe behaves differently lot to lot |
| Add-on control | Puts enough chemistry on the fibre to survive washing | Too little fails early; too much stiffens the hand and can affect colour |
The practical consequence: a fluorine-free finish cannot be judged on the as-received swatch. The as-received figure is the easiest number to dress up, and it is the one number that says least about the shipped fabric.
4. Handfeel: the half of the trade-off nobody writes down
Durability and handfeel pull against each other on the same recipe. Raising the crosslinker ratio and the add-on improves wash durability, and both of them tend to stiffen the fabric. Silicone-based fluorine-free systems generally leave a softer, more lubricious surface than a fluorinated system on the same base fabric — but softness bought with silicone alone is softness that does not survive washing.
Handfeel is not a machine-read property in this scope, so it has to be judged in a way that survives review:
- Judge the washed swatch, not the fresh one — handfeel after 5 or 10 washes is what the wearer feels, and it is also where a durability-driven recipe shows its stiffening.
- Judge on the correct base — the same recipe on a different face fabric, weight or weave gives a different verdict, so the swatch has to be the article being quoted.
- Keep an untreated reference swatch — comparing against the grey fabric of the same lot is the only way to say what the finish changed.
- Keep the panel and the conditions constant — different people and different rooms produce different verdicts; the useful comparison is the same panel on the same day.
- Separate the finish from the fabric — drape, surface friction and colour change are three different observations, and they should be recorded separately rather than collapsed into "bad hand".
5. What a fluorine-free route does not cover
Two limits belong in the technical specification from the start:
- Oil repellency. Fluorine-free systems typically reach a lower oil repellency grade than fluorinated ones — the usual trade comparison is around grade 2–3 against grade 6–8. If the requirement includes oil repellency at a high grade, a fluorine-free route alone will not carry it. See the companion article on three-proof finishing for how that requirement is written and tested.
- Water resistance is a different property. Spray rating measures repellency. Hydrostatic pressure measures resistance to water penetration, and it is read under GB/T 4744, ISO 811 or AATCC 127. A fluorine-free finish does not automatically raise hydrostatic pressure; a membrane or coating does that.
6. Common pitfalls
| Pitfall | What it looks like | Cause |
|---|---|---|
| Judging only the as-received swatch | Sample is approved, then the brand reports the rating has dropped by the third wash | The wash tier was never tested at sample stage |
| Naming a wash count without the washing standard | The spec says "washes 20 times" with no standard named | Tier and standard define the test; either one alone is unreadable |
| Reading a spray grade with no scale | "Grade 4" appears in the spec, and nobody knows whether points or grade is meant | AATCC 22 reports points, ISO 4920 and GB/T 4745 report grades |
| Confusing repellency with water resistance | A buy requirement reads "grade 4 waterproofing", and hydrostatic pressure data is offered | These are different tests on different instruments |
| Buying softness with silicone only | The fresh swatch feels excellent and the washed swatch is flat | No crosslinker, or under-cured |
| Changing the auxiliary lot mid-programme | First lots pass, later lots fail post-wash | A new auxiliary batch needs re-verification against a retained sample |
7. Working order for development teams
- Fix the standard, the tier and the washing standard in the technical specification — three items, written down, before quotation.
- State the handfeel expectation in words the supplier can act on — which reference fabric the hand should sit near, and whether the washed or fresh state is being judged.
- Test post-wash at sample stage, not after bulk production.
- Decide the oil repellency requirement separately, because it is the one item a fluorine-free route may not carry.
- Keep a retained sample of every approved lot, so a later complaint can be traced to a specific roll.
Criteria Table: How to Tell Whether Fluorine-Free Durability and Handfeel Were Actually Delivered
| Criterion | What Passing Looks Like | Common Failure |
|---|---|---|
| The spray rating standard is named on the report | The report states AATCC 22, ISO 4920 or GB/T 4745, and the standard matches the one the buyer will judge against | The report says "water repellent" with no standard number, so the grade cannot be compared with the buyer's own reference test |
| The rating is given in the right unit | AATCC 22 results are given in points and ISO 4920 or GB/T 4745 results in grades, and the unit is printed with the figure | A figure is quoted with no scale, so a points result is read as a grade result or the reverse |
| The wash tier is stated with a count | The report states the exact tier, such as as-received, after 1–5 washes, after 6–10 washes, after 11–15 washes or after 20 or more washes | The report says "after wash" without a number, so nobody can tell which durability tier was reached |
| The washing standard is named beside the count | The post-wash figure is tied to GB/T 8629, ISO 6330 or AATCC 135, printed on the same report | A wash count is written down with no washing standard, and the candidate standards apply different mechanical action |
| The route is declared as C0 | The fluorine-free finishing is described as the C0 route, covering silicone, polyurethane or bio-inspired systems | "Fluorine-free" is claimed with no route named, which leaves the oil repellency trade-off unstated |
| The oil repellency limit is acknowledged | The specification states which oil repellency grade is required, and the answer states plainly whether the C0 route carries it | A high oil repellency grade is assumed to come with the fluorine-free water repellency, and it does not |
| The crosslinking route is visible in the process description | The supplier describes crosslinker use and a curing step, not just an auxiliary name | The finish is described as a dip-and-dry auxiliary, and the washed swatch rating collapses |
| Curing is verified, not assumed | Fabric temperature or the curing step is confirmed against the recipe on the actual line | Under-curing passes the fresh swatch and fails after washing, and the cause is never found |
| The handfeel verdict names the state it was taken in | The handfeel note states whether the judge was made on the fresh swatch or on the washed swatch, and on which base fabric | A handfeel comment with no state named cannot be reproduced, and a soft fresh swatch is mistaken for a soft finished article |
| An untreated reference swatch exists | A grey-fabric swatch of the same lot is retained so the change caused by the finish can be isolated | No reference swatch survives, so any handfeel complaint is argued rather than measured |
| A retained sample exists for the approved lot | A same-lot retained sample is kept so a later post-wash complaint can be traced to a specific roll | No retained sample survives, and a bulk complaint cannot be traced to any lot |
| Post-wash testing happened before bulk | The tier result exists at sample stage and the same tier is re-checked on bulk | The tier is tested only on the bulk order, where a failure is expensive to correct |
Related Reading
- Three-Proof Finishing: How Wash Durability Is Tested — companion article, water / oil / stain repellency together
- Waterproof and Breathable Performance Targets by Use — companion article, which property binds for which end use
- Spray Rating and Water Repellency: AATCC 22, ISO 4920 and GB/T 4745 Aligned — existing article, reading a spray grade correctly (draft
content/drafts/en/02-water-repellency-guide.en.md) - PFAS Testing: Verifying a C0 Fluorine-Free Claim Substance by Substance — existing article, the compliance half of the same question (draft
content/drafts/en/04-pfas-testing-guide.en.md) - Fluorine-Free Water-Repellent Development Checklist — existing article, the development checklist rather than the judging criteria (published slug, category per CMS)
- Dry Coating — process page, where the repellent finish and coating routes sit
- Process Knowledge — Resource Section — section page
Suzhou Tutaike Textile Technology Group Co., Ltd. (formerly Wujiang Tutaike Textile Finishing Co., Ltd.) Website: https://www.szttk.com.cn