The treatment that makes rain bead on a jacket’s surface has a specific job: helping water run off instead of wetting the outer fabric. Some of these treatments use PFAS, a large family of fluorinated chemicals. Finding replacements means establishing which properties an alternative can preserve—and which it cannot.
A 2019 laboratory study found that the best non-fluorinated finishes matched the water repellency of the short-chain fluorinated finishes tested. But they offered less protection against certain other liquids, including olive oil. The researchers considered the alternatives suitable for consumer outdoor clothing, while judging their liquid repellency insufficient for some occupational protective uses. Journal of Cleaner Production (source, opens in new tab)
Journal of Cleaner ProductionHighly fluorinated chemicals in functional textiles can be replaced by re-evaluating liquid repellency and end-user requirementsOpen source (opens in new tab)
That finding concerns the fabric’s surface treatment. It does not establish whether a whole jacket is waterproof, meaning that it stops water passing through the garment. Nor does it show how the finish survives everyday use: the researchers tested freshly treated fabric, without washing, abrasion or wear tests.
The comparison used one black woven polyester fabric. Only the fluorinated finishes provided sufficient protection against olive oil and simulated gastric fluid, a liquid used to represent stomach contents. Both are more difficult to repel than water because they have lower surface tension—a property that affects how readily a liquid spreads rather than forming droplets. A treatment can therefore perform well against water while falling short against these other liquids.
This makes the intended use important. The researchers’ recommendation for consumer outdoor clothing was not a finding that every protective function of a fluorinated finish could be replaced. Their results distinguished between water repellency and protection against a wider range of liquids.
A separate 2025 study addressed durability for one particular alternative coating, made with chitosan, modified starch and zinc oxide. Tested on cotton and polyester, it maintained water repellency through multiple washing cycles and showed abrasion resistance of at least 20,000 cycles. Those results concern that coating under the reported test conditions; they do not establish how PFAS-free finishes generally perform, or how long a commercial jacket would last. Carbohydrate Polymers / PubMed (source, opens in new tab)
Carbohydrate Polymers / PubMedBreaking free from PFAS: biocompatible, durable and high-performance octenyl succinic anhydride (OSA)-modified starch/chitosan coating with ZnO for textile applicationsOpen source (opens in new tab)
The question of replacement has practical urgency. Since 10 October 2026, EU restrictions have applied to PFHxA, a particular PFAS chemical, its salts and related substances above specified limits in consumer clothing, related accessories and footwear. This is a targeted restriction, not a ban on the entire PFAS family. EUR-Lex (source, opens in new tab)EUR-LexCommission Regulation (EU) 2024/2462Open source (opens in new tab)
The evidence supports a specific possibility: replacing fluorinated finishes while retaining strong water repellency in some outdoor-clothing applications. Establishing equivalent oil resistance or lasting performance in a finished garment requires evidence beyond water beading on newly treated fabric.
- Journal of Cleaner Production · Peer-reviewed studyHighly fluorinated chemicals in functional textiles can be replaced by re-evaluating liquid repellency and end-user requirementseprints.whiterose.ac.uk · opens in new tab
- Carbohydrate Polymers / PubMed · Peer-reviewed studyBreaking free from PFAS: biocompatible, durable and high-performance octenyl succinic anhydride (OSA)-modified starch/chitosan coating with ZnO for textile applicationspubmed.ncbi.nlm.nih.gov · opens in new tab
