Water-Repellent
A fabric treatment that causes water to bead up and roll off the surface rather than being absorbed.
Water-repellent finish creates a hydrophobic surface that causes water droplets to bead up and roll off rather than penetrating the fabric structure. This protection differs fundamentally from waterproof treatments, which completely block fluid transmission—water-repellent fabrics remain breathable while shedding surface moisture.
DWR Hydrophobic Surface Beading vs Penetration
Cross-section: Contact angle > 110° prevents liquid water from wetting woven polyester filaments.
How DWR works: surface energy physics
Water repellency is governed by the relative surface energy between the liquid droplet and the textile substrate:
- Water has a high surface tension of approximately 72.8 mN/m.
- Untreated synthetic filament polyester has a surface energy of 43 mN/m, allowing water to wet and spread across fiber interstices.
- When finishing mills pad and cure a DWR (Durable Water Repellent) agent, hydrophobic fluorochemical or hydrocarbon chains bond to the fiber exterior, dropping surface energy below 20 mN/m.
Because the liquid surface tension is substantially higher than the fiber surface energy, water cannot wet the fabric; instead, cohesive forces pull droplets into spheres with contact angles exceeding 110° to 130°, allowing gravity to roll them off.
Testing standards: the AATCC 22 spray rating
In mill quality control and international trade, water repellency is evaluated under AATCC Test Method 22 (ISO 4920). The specimen is mounted on a 45-degree testing hoop and sprayed with 250 mL of distilled water from a standardized nozzle under gravity:
| AATCC 22 Rating | Visual Wetting Pattern | Commercial Acceptance Criteria |
|---|---|---|
| 100 | Zero wetting; no sticking or water droplets on upper face | Initial benchmark for technical outdoor jackets, umbrellas, and marine shells |
| 90 | Slight random sticking or wetting at isolated points | First quality commercial acceptance threshold after laundering |
| 80 | Wetting of upper surface at spray impact points | Standard commercial minimum threshold after 20–30 domestic wash cycles |
| 70 | Partial wetting of the whole upper face beyond impact points | Marginal performance; fails technical outerwear and performance export specs |
| 50 / 0 | Complete surface wetting through to reverse face | Total failure; represents untreated greige or scoured cloth |
C6 DWR vs Fluorine-Free (PFC-Free / Zero-F) DWR
Global environmental regulations have shifted industrial finishing routes from legacy long-chain (C8) fluorocarbons to C6 and fluorine-free alternatives:
| Technical Parameter | C6 Fluorocarbon DWR | Fluorine-Free DWR (PFC-Free / Zero-F) | Mill Sourcing Trade-Off |
|---|---|---|---|
| Active Chemistry | Perfluoroalkyl short-chain () | Plant-based dendrimers, waxes, or modified silicones | C6 uses fluorinated chemistry; Zero-F is hydrocarbon-based. |
| Water Repellency | Outstanding (Initial AATCC 22 = 100) | Outstanding (Initial AATCC 22 = 100) | Both achieve identical initial water beading and run-off. |
| Oil & Stain Repellency | High (repels hydrocarbon oils, grease, sauce) | Zero (repels water only; absorbs oils immediately) | Choose C6 for workwear and uniforms; Zero-F for consumer sportswear. |
| Environmental Compliance | Free of PFOA/PFOS; regulated under EU REACH | 100% PFC-free; OEKO-TEX STANDARD 100, ZDHC MRSL, Bluesign | Zero-F complies with global green retail brand mandates. |
| Wash Durability | Retains 80+ rating after 20–30 domestic washes | Retains 80+ rating after 20–30 domestic washes | Durability depends heavily on proper stenter curing temperatures. |
| Thermal Reactivation | Tumble drying or iron heat realigns fluorocarbon chains | Dependent on cross-linker; less heat-reactive than C6 | C6 regains performance after tumble drying. |
| Cost & Processing | Established, cost-effective formulation | Slightly higher chemical cost; requires cleaner fabric prep | Zero-F requires zero surfactant residue on the base cloth. |
Buyer PO checklist for water-repellent fabrics
To prevent quality disputes and ensure the mill sets up the stenter range correctly, include this 5-point technical checklist on your purchase order:
- Initial Spray Rating Target: Specify the exact acceptance standard (e.g.
AATCC 22 Spray Rating >= 90 initial (target 100)). - Laundering Durability Threshold: State the wash standard and cycle count (e.g.
AATCC 22 Spray Rating >= 80 after 20–30 home wash cycles under AATCC 135 / ISO 6330 at 40°C). - Chemistry & Environmental Compliance: Explicitly define the chemical framework:
C6 DWR(if oil/grease resistance is required for workwear) orFluorine-Free / PFC-Free DWR(conforming to ZDHC MRSL Level 3 and OEKO-TEX STANDARD 100 Class II). - Base Fabric Construction & Preparation: Ensure the substrate density matches the application. Specify tight plain weaves like taffeta (210T) or pongee (240T), and require thorough scouring/desizing because residual sizing agents or wetting surfactants will severely impair DWR bonding.
- Complementary Back Treatments: If hydrostatic head pressure resistance is required alongside surface beading, specify a reverse PA coating (400mm–1,000mm) or PU backing to create a complete weather barrier.
Common questions
What is the difference between water-repellent (DWR) and waterproof?
- DWR (durable water repellent) causes water droplets to bead up and roll off the face while maintaining air permeability and breathability; waterproof requires a solid barrier membrane like PU or TPU coating or laminate resisting hydrostatic water column pressure.
How is water repellency measured in textile mills?
- In textile mills, water repellency is measured using the AATCC 22 Spray Test: 100 = zero wetting, 90 = slight random wetting, 80 = wetting at spray points, and 70 = partial wetting. Commercial outdoor standard is 90+ initial, and 80+ after 20 home wash cycles.
What is C6 DWR vs Fluorine-Free (PFC-Free) DWR?
- C6 fluorocarbon provides both water and oil repellency; fluorine-free DWR offers excellent water repellency without bio-accumulative fluorochemicals, satisfying OEKO-TEX and ZDHC standards but does not repel oils.
How long does a DWR finish last on polyester?
- Commercial mill-applied DWR maintains an AATCC 22 rating of 90+ initial, and retains 80+ after 20 to 30 domestic wash cycles. Low-temperature tumble drying or light ironing reactivates the hydrophobic polymer chain alignment.
Related Terms
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