Pertex® Quantum Air: Moving from C6 to C0 DWR

Updated November 4, 2026

Following our previous tests, we conducted another field test in temperatures around 5°C, comparing products with lower and higher air permeability.

We found no significant difference in warmth, wind resistance, or overall comfort. Taking into account how easily the hood can be put on or removed to regulate body temperature, we concluded that the lower-air-permeability fabric performs sufficiently well for the Light Alpha Only Hood.

Based on these results, the Light Alpha Only Hood in Black will be available starting at 18:00 JST on November 5.

Updated October 27, 2026

Since Fall/Winter 2025, we switched the DWR treatment on the Pertex® Quantum Air used in the Light Alpha Vest/Jacket, Alpha Anorak, and Light Alpha Only Hood from C6 to the Pfas-free C0 coating to reduce environmental impact. However, testing of the production fabric revealed differences in air permeability depending on the color and production batch.

As these variations were only discovered after production, we decided to take a cautious approach until further field testing could be completed. We adopted 33 cc/cm²·s, the air permeability of the fabric used in our original Alpha Anorak released in 2017, as our internal benchmark. Products that fell below this initial benchmark will be listed as Special Offer items.

Since then, we’ve continued field testing products made with fabrics that have lower air permeability. Our tests confirmed that even at around 20 cc/cm²·s, the fabric provides sufficient ventilation to release excess heat and moisture during activity while retaining the warmth needed. We also found that lower air permeability offers the benefit of greater wind resistance.

Higher air permeability allows heat to escape more easily, but it also lets more wind through. Lower air permeability has the opposite effect, retaining more warmth while providing greater wind resistance.

Our goal isn’t simply to maximize airflow, but to find the right balance between breathability and warmth during activity.

Based on these findings, we’ve revised the minimum air permeability standard for the 2026 Light Alpha Vest/Jacket and Alpha Anorak from 33 to 20 cc/cm²·s. We will continue using C0 DWR for the outer fabric.

During our latest inspections, we also found that some of the Black fabric had an air permeability of approximately 13–15 cc/cm²·s, below our revised standard of 20 cc/cm²·s.

We decided to use this fabric for the Light Alpha Only Hood, as its design makes temperature regulation easy by allowing you to take it on and off or vent around the face opening. We believe the added wind resistance could outweigh the reduced airflow in this particular design.

However, field testing of this fabric is still ongoing. The Black Light Alpha Only Hood will be available once we’ve confirmed its performance in actual use.

Published December 8, 2025

From Fall/Winter 2025, we’re switching the DWR finish on Pertex Quantum Air used in the Light Alpha Vest/Jacket, Alpha Anorak, and Light Alpha Only Hood from C6 to C0.

The change reduces the environmental impact of the finish, but during testing and production we also found greater variation in the fabric’s air permeability than with the previous C6 treatment.

Here, we’d like to explain what changed, what we found through testing, and how we’re handling products that fall below our usual benchmark

The former C6 DWR finish contains small amounts of perfluoroalkyl substances (PFAS), which are resistant to degradation in nature and can persist for long periods in soil and other environments. C0 DWR, on the other hand, does not use PFAS and therefore has a lower environmental impact.

However, compared with C6 DWR, the C0 treatment tends to penetrate deeper into the fabric, which can lead to variations in air permeability and perceived wind resistance.

Although our prototypes showed sufficient breathability, air permeability measurements taken during production revealed noticeable differences between color batches.

Through this testing, we confirmed that Pertex Quantum Air treated with C0 DWR may show some variation in breathability from product to product.

Based on the Pertex Quantum Air used in the first-generation Alpha Anorak—which had an air permeability of 33 cc/cm²·s—we set our internal benchmark at 33 cc/cm²·s or higher, as this level provides a strong balance of breathability and warmth.

Fabrics that fall below this benchmark are sold separately at a 20% discount.

Even so, these lower-rated fabrics still average 26.5 cc/cm²·s, which is generally considered highly breathable. The lower air permeability also means slightly more warmth. While this falls outside our intended balance of breathability and warmth, it may suit hikers who tend to run cold or expect to use the jacket primarily in colder conditions.

This change has also shown us how difficult it can be to balance environmental considerations with consistent performance.

We’ll continue testing and evaluating materials carefully, looking closely at how they perform in real use and making choices that we believe work best on the trail.