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Revolutionary Waterproof Zippers Developed in Collaboration with YKK: "finetrack"'s Ultimate Achievement in Rainwear

2025.04.16

"finetrack" is an outdoor brand founded by Yotaro Kanayama in 2004, after he worked in planning and development at a major outdoor manufacturer.

With the motto of "gear that prioritizes functionality to protect life over fashion trends," this brand focuses on Japan-made craftsmanship, gaining strong support from discerning outdoor enthusiasts.

The masterpiece rainwear, "EVERBREATH PHOTON," which showcased Finetrack's prowess, has been renewed after 8 years.

The product planning manager, who knows this item inside and out from its inception to this recent improvement, shares insights about the revamped Everbreath Photon.

PROFILE

So Aikawa

finetrack Co., Ltd.

Established in 1975. After working as an engineer at an inspection equipment manufacturer, he joined Finetrack in 2008. Learning about outdoor product planning under the owner, Kanayama, he currently serves as the head of the product planning department. His hobbies include outdoor activities, such as backcountry telemark skiing, canyoning, and climbing during weekends.

Rainwear Using Unique Waterproof Breathable Material, Everbreath

"Everbreath Photon," 38,500 yen (tax included)

Can you tell us about the background of Everbreath Photon?

In 2012, we launched the first model, "Everbreath Photon Suit."

At that time, there were hardly any outdoor rainwear made with stretch fabric, most of which were difficult to move in and had a bulky silhouette, making them clothes that one wore out of necessity for rain protection.

So, we decided to create rainwear using stretch fabric that is easy to move in, comfortable to wear, and also beautifully tailored.

In addition to stretchiness, we also focus on "durability of function." This means it maintains waterproof pressure and breathability even after prolonged wear in the rain.

This "excellent stretchiness" and "durability of function" have been core design philosophies of Everbreath Photon from the beginning and continue in the new model.

What is the primary material?

It's a unique waterproof breathable material called "Everbreath" that we developed ourselves. It features outstanding stretchability, utilizing fabric that stretches approximately 107% vertically and about 117% horizontally in current models.

However, just having stretchable fabric doesn't guarantee perfect comfort. Especially in rainy fields, it is essential to have waterproofing and breathability that persists even when wet.

Indeed, if the body gets wet from sweat, it defeats the purpose of protection from rain.

While climbing in the rain, a waterproof pressure of over 10,000mm is deemed necessary to cope with instantaneous pressure from movements.

Therefore, we designed fabric that can maintain waterproof pressure of over 20,000mm and breathability over the long term.

How do you achieve high durability of function?

Both the outer stretch fabric and the inner knit fabric are treated with durable water-repellent processing.

By focusing on not only excellent waterproofing and breathability but also ensuring prolonged functionality, we create rainwear that allows comfortable prolonged use in even the harshest environments.

How long does waterproofing last?

As for specific duration, it varies depending on the environment and usage, so we haven't conducted verifications.

However, the renewed Everbreath Photon has been proven to maintain waterproof properties even after approximately 20,000 stretch tests and about 30,000 abrasion tests through waterproof pressure retention rate measurement tests.

Moreover, using a polycarbonate-based polyurethane that is resistant to hydrolysis in the fabric composition also helps endure hard use.

High waterproof pressure retention is a distinguishing feature

The details are also meticulously crafted.

The hood is designed to fit the head whether wearing a helmet or not, and it is equipped with sound exit holes for better sound perception from behind.

The large side ventilations, known as link vents, are positioned in common places with mid-layers, enabling efficient ventilation. These details have been carried over from the first model.

What is the Power of the New Waterproof Zipper Developed with YKK?

It looks like it's the fourth renewal in eight years. What has evolved in the new model?

The biggest change is the zipper. Finetrack collaborated with YKK, a leading global zipper company, to develop a new zipper called "AquaGuard® Tightened."

How is it different from traditional waterproof zippers?

A waterproof zipper is one where the surface of the zipper tape is laminated with polyurethane film. When the zipper is closed, the tape adheres closely, making it difficult for water to penetrate through small gaps.

While the structure is lightweight and compact, it actually lacks water resistance without a flap to withstand rainfall.

You have overcome the shortcomings of traditional waterproof zippers.

In the case of AquaGuard® Tightened, the left and right zipper tapes adhere closely together, creating an M-shaped bulge. This structure significantly reduces the infiltration of rainwater.

While traditional waterproof zippers adhere along a “line,” AquaGuard® Tightened adheres across a “surface,” which greatly enhances its water resistance compared to conventional waterproof zippers.

Furthermore, due to the high water pressure resistance of the zipper itself, we could eliminate the flap that covers against water ingress. As a result, there are no longer troubles caused by the zipper catching on the flap, and the simplification around the zipper has resulted in a cleaner silhouette.

A Groundbreaking Structure Inspired by Refrigerator Seals

How did the development start?

We started making requests to YKK around 2018, and the full-scale development began in 2020. While there were already zippers with high waterproof features, they were large in shape and difficult to use in general apparel.

What we sought was a zipper that had the same size and weight as traditional waterproof zippers but could demonstrate high water resistance without a flap.

The structure where the left and right tapes adhere closely was conceived by YKK's developers after much trial and error, inspired by the seals of refrigerators.

It took quite a while to complete.

The first prototype was completed in 2022, and after field testing and cooperation on feedback, we finally managed to commercialize it this year.

The most challenging aspect was the zipper's sliding performance. This refers to the low friction and smoothness of the material, which is crucial for a zipper that is frequently opened and closed.

Increasing water resistance lowers sliding performance, and on the contrary, focusing on sliding performance sacrifices water resistance. To adjust that balance, YKK's developers repeated prototypes, and we conducted field tests multiple times.

This season features five color variations

Are there any other improvements?

We also revised the design of the fabric and incorporated new technologies.

First, we changed the yarn usage, fabric structure, and the knit lining to ensure that even with heavy use, the water pressure can be sustained.

This has improved the durability of stretching, fabric abrasion resistance, and resistance to damage to the waterproof and breathable membrane caused by sweat and oil stains.

The texture has also been finished in a distinctly matte style, permitting a color range that utilizes subdued hues.

With the renewal, the overall quality as rainwear has greatly improved.

Finetrack has continually pondered, "What is the mission of rainwear?"

Simply providing shelter from the rain is not enough. Supporting safe activities in nature and ensuring a safe return is essential. Moreover, it is about providing comfort to the user. This is the mission of Everbreath Photon.

The collaboration with YKK on the AquaGuard® Tightened carries significant meaning, as this new zipper's debut will lead to even simpler and lighter structures for rainwear and a broader scope for designs in the future.

The reborn Everbreath Photon holds the potential to become a new theory in rainwear.

Text by Ryota Osujo