Second Light Windshell
Skip until Stio discloses water-repellent coating chemistry.
Stio's Second Light Windshell has a nylon shell with water-repellent finish but the brand does not disclose coating type or PFAS status. Without certification or transparency, PFAS risk cannot be ruled out.
Still want this one anyway? Check the price on Amazon. We’d swap it.
Material
Nylon shell with unspecified water-repellent coating
Brand disclosure
Brand is silent on PFAS
Lab data
No public lab test
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What Second Light Windshell is made of, ingredients and materials
The Stio Second Light Windshell is a nylon shell with an unspecified water-repellent (water-repellent coating) coating. Nylon itself is a synthetic polymer with low toxicity risk during normal wear, but the water-repellent coating finish is the critical unknown, most nylon windshells use fluorocarbon-based coatings (PFAS) to achieve water repellency, which can shed microparticles and off-gas during heat exposure, manufacturing, or wear. Without disclosure from Stio, the coating chemistry cannot be verified as PFAS-free or low-concern.
What’s concerning
Waterproof / stain-resistant treatment
Water-repellent coating treatments have historically used PFAS.
Category baseline
The starting point for this type of product, before anything specific to this product is counted.
No PFAS disclosure
No public statement from the brand about PFAS in this product.
PFAS
Nylon windshells overwhelmingly use PFAS-based water-repellent coating coatings; Stio's refusal to disclose makes PFAS presence probable. No recall or lab test specific to this model is on record, but the material class and brand silence are consistent with historical industry practice.
Source, ATSDR ↗Formaldehyde / VOCs
Nylon is often finished with formaldehyde-based resins to improve crease resistance or dimensional stability. Stio does not specify finishing chemistry. Off-gassing risk is low during normal wear but possible during manufacturing or in damp storage.
Source, ATSDR ↗Microparticle shedding from coating degradation
Water-repellent coating coatings on nylon degrade over time and with washing, shedding microparticles into water and air. If the coating is PFAS-based, these particles carry PFAS; even PFAS-free coatings shed particles that may be inhaled or ingested via water systems.
What’s reassuring
Azo dyes in fabric dyeing
No specific record of azo dye concerns in Stio apparel. Nylon windshells are typically solid-colored and may use reactive dyes rather than azo dyes, but without dyeing process disclosure, this remains unverified.
Antimony in polyester (not applicable here)
This product is nylon, not polyester; antimony is not a relevant hazard class for this material.
How is this PFAS grade calculated?
The brand's record and disclosure
Stio does not publicly disclose the chemistry or brand of its water-repellent coating, nor does the company appear to have published PFAS commitments or certifications (such as OEKO-TEX, Cradle to Cradle, or bluesign). This silence is notably absent in a category where competitors like Patagonia, Arc'teryx, and The North Face have disclosed moves toward PFAS-free or PFOA-free formulations. Lack of transparency is a red flag in apparel where water-repellent coating chemistry directly affects end-user and environmental exposure.
How it compares in its category
Most windshells in this price and performance tier still use legacy PFAS-based water-repellent coating coatings; however, an increasing number of mainstream brands now offer PFAS-free or certified low-PFAS alternatives. Stio's refusal to disclose places this windshell in the higher-risk segment of the category. Brands that openly commit to PFAS phase-out or use fluorine-free repellent systems (wax-based, silicone, or newer chemistries) are lower-concern alternatives for the same use case.
If you buy it
Do not machine wash in hot water; PFAS off-gassing and particle shedding increase with heat. Wash in cold water and air dry. Avoid prolonged sun exposure or storage in hot cars. Expect the water-repellent coating to degrade over 50-100 washes; reapplication with aftermarket products will reintroduce uncertainty around coating chemistry. Consider a transparent disclosure request to Stio before purchase, or choose a competitor with published PFAS-free or low-concern water-repellent coating chemistry.
What is not known about PFAS in this product?
- Basis
- Model estimate, 35% confidence, not a lab result
- Lab test
- None on record for this exact product
- Brand statement
- Stio has made none
Formulations change between production runs, so check the current label. How we grade.
More rain jackets grades
How we score, every product runs through the same public 0-100 rubric based on materials, coatings, brand disclosure, lab findings, and recalls. See the full methodology → Spotted a mistake? Report an error.