Reviews
PFC-Free Waterproof Coatings on Bio-Based Jackets: How to Test
PFC-free waterproof coatings bio-based jackets lose repellency with wear. Track the AATCC 22 spray rating after five washes and know what it cannot measure.
What to take away
- A PFC-free waterproof coating on a bio-based jacket can handle light to moderate rain when new, but it will lose repellency faster than a fluorinated finish.
- The metric to track is the AATCC 22 spray rating, measured before and after five launderings.
- A rating below 80 after five washes is the threshold to reapply the finish or stop relying on that jacket for rain.
- This rating cannot measure breathability, seam tape failure, or how much microplastic the shell sheds.
- Waterproofness needs a hydrostatic head test (AATCC 127 or ISO 811), and the PFC-free claim needs a fluorine analysis from a laboratory.
U.S. outdoor brands have moved many rain shells away from long-chain per- and polyfluoroalkyl substances. The U.S. EPA reports that these compounds persist and can accumulate in people and the environment. California Proposition 65 warnings have also pushed buyers toward jackets labeled with a bio-based water repellent finish. For a bio-based jacket to meet U.S. rainwear expectations, you need a repeatable number, not a marketing claim.
What to measure
The AATCC 22 spray test is the standard measure. A fixed volume of water sprays on the fabric at a set angle. The surface is rated from 0 to 100. A rating of 100 means no sticking or wetting. A rating of 90 means slight random sticking. A rating of 80 means wetting at spray points. For a new rain shell, insist on a rating of 90 or higher.
Measure the same jacket after five home launderings using the care label. The decline matters more than the new rating. Dirt, body oil, and abrasion remove a bio-based finish faster than a fluorinated one. A fluorinated DWR once held ratings above 90 for many washes, but those finishes rely on the same PFAS chemistry. The bio-based shell may be made from recycled polyester or bio-based polyester. Recycled Polyester vs Bio-Based Polyester explains the substrate differences.
How to read it
| Condition | AATCC 22 rating | What it means |
|---|---|---|
| New bio-based jacket | 90 to 100 | Ready for light to moderate rain |
| After five washes | 80 to 89 | Works but reapply soon |
| After five washes | Below 80 | Reapply or replace for rain use |
| After heavy abrasion | Variable | Test before relying on it |
The table is a guide, not a warranty. A rating of 80 means the fabric wets at spray points. That is enough to feel cold or clammy in sustained rain. U.S. buyers often expect a rain shell to bead water for a full season. A bio-based DWR will need more frequent reapplication to meet that expectation.
AATCC 22 Rating Guide
Condition
- New bio-based jacket
- 90 to 100
- After five washes
- 80 to 89
- After five washes
- Below 80
- After heavy abrasion
- Variable
Rating
- New bio-based jacket
- Ready for light to moderate rain
- After five washes
- Works but reapply soon
- After five washes
- Reapply or replace for rain use
- After heavy abrasion
- Test before relying on it
Meaning
- New bio-based jacket
- After five washes
- After five washes
- After heavy abrasion
A rinse cycle alone will not restore a bio-based DWR. The rating drops because the finish has worn away or become coated with oils, not because the jacket is dirty.
What it cannot tell you
The AATCC 22 spray rating does not measure water pressure through the fabric. A jacket can bead water on the surface and still leak at the seams. It also does not measure breathability. A stiff, waxy bio-based coating can score high on spray rating while trapping sweat. For a fuller picture, look for the hydrostatic head rating in millimeters and a breathability test such as ASTM E96, but those are separate metrics.
What Spray Rating Misses
- Water pressure through fabric
- Seam leakage
- Breathability
- Sweat trapping
- Microplastic shedding
Two more tests: water pressure and the PFC-free claim
The spray rating covers the surface finish. Two further tests complete the picture for a PFC-free waterproof coating.
Waterproofness. Hydrostatic head is measured with AATCC 127 (Water Resistance: Hydrostatic Pressure Test) in the U.S. market or ISO 811 internationally. A column of water presses on the fabric until drops come through; the result is the water height in millimeters. Ask for the result on the coated shell fabric after the same five launderings, and test a seam sample as well, because taped seams fail separately from the fabric.
The PFC-free claim itself. A spray rating cannot show whether a finish is free of fluorine chemistry. Ask the supplier which chemistry the finish uses. PFC-free DWR finishes are typically based on silicones, paraffin or other waxes, hydrocarbon polymers such as polyurethanes, or dendrimers; a bio-based DWR uses plant-derived waxes or oils within these families. Then ask for a laboratory report: a total fluorine screen, followed where needed by targeted PFAS analysis with LC-MS/MS, for example under the EN 17681 series for organic fluorine in textiles. A finish described as PFC-free without such a report is a supplier statement, not a test result.
A separate article asks whether Bio-Based Synthetics Shed Microplastics, and the spray rating cannot answer that either.
Attribution and its limits
A drop in spray rating can come from several causes. Abrasion from pack straps scrapes the finish. Body oils from the neck and cuffs contaminate the surface. Detergent residue can mask the finish. The AATCC 22 test cannot separate these causes. It only records the outcome.
Causes of Rating Drop
- Abrasion from pack straps
- Body oils from neck and cuffs
- Detergent residue
- Finish not fully cured
- Wrong detergent used
A poor rating may reflect hard use, the wrong detergent, or a finish that was never fully cured. Check the care label. Most bio-based DWRs require a cleaner without fabric softener. If the jacket has not been washed clean before testing, the number will mislead you.
A lab test will control for detergent and abrasion, but a home user rarely does. That gap is why the number should guide action, not assign blame. The spray rating also loses meaning if the jacket has been worn against a backpack for a full season.
For guidance on how finishes interact with the rest of the garment, see the article on textile dyes and finishes. That piece explains why some bio-based finishes fail after contact with certain dyes and washes.
When to stop measuring and decide
If the AATCC 22 rating falls below 80 after five washes, stop tracking and act. Reapply a bio-based DWR according to the product instructions. If the jacket still wets out after reapplication, it is time to use a different shell for rain. Three consecutive measurements below 80 tell you the finish is not recovering.
When to Stop Measuring
Rating below 80 after five washes?
Reapply DWR, then retest
Continue monitoring
Do not keep measuring week after week hoping the number improves. A bio-based water repellent finish does not self-heal. Once surface wetting becomes visible on the shoulders and chest, the useful rain protection has already declined.
A single low rating after a muddy hike is not a reason to abandon the jacket. Wash it, reapply the DWR, and test once more. The threshold is for a clean, laundered jacket, not one straight off the trail.
Before trusting a bio-based content claim, check the USDA BioPreferred Label for clothing to see what is verified. The label covers the fiber and material content, not the waterproof coating. That distinction matters for a rain shell.
