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Polartec AirCore from Castelli aims to redefine breathability

10/9/2025

Translation: machine translated

Castelli and Polartec are teaming up to launch a new material on the market: Polartec AirCore. The technology will initially be used in a cycling jacket. Further products are to follow.

The Italian manufacturer of cycling clothing Castelli has teamed up with the American functional fabric pioneer Polartec to develop what it claims is a revolutionary new material «» . Polartec AirCore is said to be a true miracle material. At least if Castelli's media release is to be believed.

The first product to feature the new technology is the «Perfetto RoS 3» jacket, which according to the manufacturer is the «perfect jacket for rain or shine». The combination of air permeability and Polartec's nanofibre membrane ensures that Polartec AirCore keeps the rider dry and at the same time guarantees the windproofness and water repellency of the fabric.

However, water vapour can only escape from the inside to the outside if it can also be absorbed in the atmosphere. If the humidity outside the jacket is almost 100 per cent when it rains, it will still be damp inside. This is not surprising, it is physics. Even the most flowery marketing promises of a manufacturer are of no use.

Nonetheless, or perhaps precisely because of this, I will be testing the new jacket extensively over the next few weeks and reporting on my impressions. Castelli has provided me with a sample for this purpose.

Miracle fabric or just clever marketing? Polartec AirCore.
Source: Castelli

Essentially windproof and waterproof

As the manufacturer goes on to write, «the material is essentially windproof and waterproof.» What exactly does that mean? «The jacket has been designed to allow a very small, barely perceptible amount of air through, which absorbs perspiration and channels it outwards. This keeps riders drier than would ever have been possible with a membrane jacket.»

Laboratory tests have shown that the new material offers an air permeability of 0.7 cubic feet per minute (CFM) - in contrast to most competitor fabrics, which have no air permeability at all. The jacket also performs excellently in terms of water vapour permeability (MVTR) with 35,000 g/m²/24 hours. This means that 35 kilograms of water vapour can escape per square metre within 24 hours. By way of classification: a membrane is considered very breathable from 10,000, with the very best achieving up to 40,000. However, this MVTR value, which is standard in the industry, does not take air permeability into account and therefore has little real significance.

AirCore is also essentially waterproof, according to the press release. Here too, the term «essentially» is used deliberately, as fabrics in many countries have to achieve a hydrostatic pressure test value of 10,000 mm. This means that a 10,000 mm water column can be pressed onto a fabric before water penetrates it for it to be considered waterproof. Castelli continues: «In reality, rain only falls with a hydrostatic pressure of around 800 mm. The test value of 5000 mm that AirCore achieves means that normal rain would have to fall with 6.25 times more force to penetrate the fabric. This means that AirCore is functionally waterproof and keeps cyclists drier in a wide range of conditions.»

The new fabric from Castelli and Polartec is «essentially» windproof and waterproof.
Source: Castelli

100 per cent PFAS-free

The fabric is 100 per cent PFAS-free, as the top and back are knitted from recycled polyester. Steve Smith, Head of Cycling at the MVC Group, comments: «'With the new PFAS-free era upon us, we wanted to start from scratch when developing our «Perfetto RoS 3» jacket. Talking to various fabric suppliers, engineers and scientists from around the world, we found in Polartec a brand that really understood our goals.»

Other features

reflective, welded shoulder seams for additional rain protection
Ventilation openings with zip on the sides
YKK Vislon zip at the top and bottom for easy gliding, covered for additional wind and rain protection
Three back pockets with drainage holes
extended back to protect against splashing water
reflective details on the pocket bottoms
high collar against draughts

The men's jacket is available in the following four colours at a price of 249.95 euros: Rich Red/Black Reflex, Light Black/Silver Reflex, Mocha/Black Reflex and Pool Blue/Black Reflex.

The women's jacket is available in the colours: Hibiscus/Black Reflex, Pool Blue/Black Reflex, Mango Mojito/Black Reflex and Light Black/Silver Reflex.

Castelli will be launching further AirCore garments on the market shortly, according to the press release.

Cycling jackets

Castelli Perfetto

Cycling jackets

Castelli Perfetto RoS 3 Jacket

Header image: Castelli

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Patrick Bardelli

Senior Editor

Patrick.Bardelli@digitecgalaxus.ch

From radio journalist to product tester and storyteller, jogger to gravel bike novice and fitness enthusiast with barbells and dumbbells. I'm excited to see where the journey'll take me next.

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