山と道

UL Rain Hoody

109g (PU Sosui)/ 98g (PU Shinsui)

¥29,150(PU Sosui)/ ¥30,250(PU Shinsui)

Introduction

Super simple shell

Our UL Rain Hoody is an ultralight three-layer rain jacket for hiking and fastpacking. To effectively shut out rain, we eliminated the center zipper, and the fabric is joined together by ultrasonic welding instead of traditional sewing and seam taping. Being lighter than a normal T-Shirt, this is properly the simplest rainwear in the world.

Choose from two different materials; the ultralight, polyurethane-based, hydrophilic, and non-porous Pertex Shield (PU Sosui), and the well-balanced polyurethane-based hydrophobic and microporous Pertex Shield Pro (PU Shinsui).

– Perhaps the world’s lightest three-layer rain jacket
– Two material choices
– Rainproof, no-zipper design
– Ultrasonic welding instead of traditional seams
– Comfortable relaxed-fit
– Can also be used as a basic windshell

  • Blue
  • Red
  • Deep Forest
  • Navy
  • Ebony
  • Nomad

Specs

Made in Akita, Japan

Material:
Pertex Shield Pro(PU Sosui)
Pertex Shield(PU Shinsui)
Weight(Size S):
109g(PU Sosui)/ 98g(PU Shinsui)
Size:
XS / S / M / L / XL

Product Story

Akira Natsume, Yamatomichi Founder

Before we made our Rain Hoody, my favorite waterproof jacket was a basic, less-than-100-grams jacket, that was sadly discontinued. That’s why I decided to create our own rain jacket, which was to be so simple and lightweight that it could be a game-changer in the rainwear market.

There is a multitude of waterproof shell jackets on the market with different functions for different purposes. For backcountry skiing or snowboarding, a jacket must provide protection against intense cold and extreme winds. For rock climbing, it should be wear-resistant because it is continuously rubbed against the rock surface. For hiking or fastpacking use, it has to be lightweight and comfortable since you may spend days in the mountains with it. Each purpose requires a different feature.

As we started to create the prototype of the Rain Hoody, we conducted a thorough investigation of different waterproof shells and breathable materials at our Yamatomichi Laboratory. We concluded that some jackets are suitable for a specific purpose, but there was nothing like a perfect jacket that would fit every situation.

For example, durability, thermal insulation, and a helmet-compatible hood are priorities for backcountry skiing/snowboarding and rock climbing use, but for hiking and fastpacking purposes, weight is the all important factor. When you go hiking on a sunny day, the jacket usually stays inside your backpack, so the lighter the better. Also, light shell jackets are usually worn during the warmer seasons, so the priority should be on breathability to avoid overheating rather than insulation.

Among many waterproof and breathable materials, the polyurethane-based hydrophobic and microporous Pertex Shield Pro was the most promising and well-balanced membrane with excellent moisture permeability and waterproof properties. The non-porous Pertex Shield was, on the other hand, significantly lighter, although it was slightly inferior to the “Pro” version in breathability and waterproof properties. Pertex Shield Pro or normal Pertex Shield? It was a difficult choice.

My focus was to create a light rain jacket weighing less than 100 grams, just like the one I had used before. I choose the normal Pertex Shield because of its lighter weight, but at the same time, I recommend Pertex Shield Pro to many of our customers as this is a really well-balanced fabric despite the added weight.

In the end, we decided to make two different jackets using both versions of the Pertex Shield. Both are three-layered, comfortable, lightweight, and surprisingly flexible. They are so comfortable that they can be used as windbreakers on a chilly morning or nightfall though a more conventional windshell jacket might have better breathability.

Since the UL Rain Hoody is so light and thin it doesn’t really provide much in terms of insulation. So when using the UL Rain Hoody at the top of a stormy mountain ridge, we highly recommend you wear a merino wool base layer like our Merino Hoody for added comfort. Even during severe weather, merino wool base layers keep you warm by properly controlling the temperature and moisture within the jacket.

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Form and Function

Simple design keeps the rain out

Even if a rain jacket is made of waterproof material, the rain can physically get in from openings around the neck, wrists, and the zippers and seams. This is why our UL Rain Hoody has no center zipper or seams around the shoulders and chest. It is designed to minimize the seams and stitches by using an ample amount of material so that it requires as few parts as possible.

Waterproof ultrasonic welding

The stitches of most waterproof jackets are usually sealed by seam tape, but this method lacks in durability, possibly resulting in leakage.

Instead of stitching and seam-taping, our UL Rain Hoody is made using ultrasonic welding instead of traditional seams, minimizing the risk of leakage from the joints.

Relaxed fit for ventilation

The UL Rain Hoody is available in either Pertex Shield or Pertex Shield Pro, both with excellent waterproof performance and breathability. In addition, its relaxed fit effectively ventilates body heat and moisture.

The relaxed-fit, however, means it requires more fabric than most other slim-fit jackets. Although the increase of the fabric can lead to weight gain, we consider the relaxed design is necessary for the smooth pull-over as the jacket comes without a front zipper.

Details

Hood

To keep out the rain, the lower edge of the hood should be under your chin, so that your chin is exposed. The rain may wet your face, but the water will run down and drip off your chin.

*DO NOT cover your chin with the hood. Water will drip off your chin and inside the Rain Hoody.

Material

Two different materials

Both Pertex Shield Pro (PU Sosui) and Pertex Shield (PU Shinsui) are three-layer waterproof and breathable materials, but the structure of the membrane, characteristics, and moisture permeation mechanisms are completely different.

Pertex Shield Pro(PU Sosui)

The Pertex Shield Pro is a polyurethane-based hydrophobic and microporous membrane. The “hydrophobic” material has high water repellency, and the “microporous” means that it has a number of very small holes (pores).

These pores are too small for liquid water (rain) to enter, but large enough for vapor (moisture from your body) to get out. Pertex Shield Pro effectively vents the moisture within the clothes from the pores, achieving superior breathability.

According to our test at our Yamatomichi Lab, Pertex Shield Pro prevents excessive temperature rise even during heavy exercise, while keeping a constant temperature when it rapidly gets cold. According to the information provided by the manufacturer, the Pro version is more durable than the regular Pertex Shield.

Pertex® Shield Pro

Material:
Pertex Shield Pro (100% NYLON)
Weight: 58g/㎡
Surface: 10d/10f x 10d/10f+30d, ripstop
Linning: 7d tricot
Water-repellent finish by C6 DWR

Specs:
Tear strength measured by JIS L 1096 D (Pendulum method)
Vertical: 1.0kg, Horizontal: 0.8kg

Tensile strength measured by JIS L 1096 A (Strip method)
Vertical: 27kg, Horizontal: 19.8kg

Breathability measured by KES method
270 or more

Water-permeability tested by JIS L 1099 A-1
11280g/㎡/day (Our measured value)

Water-permeability tested by JIS L 1099 B-1
20000g/㎡/day (Catalog spec)

Water pressure resistance tested by JIS L 1092 B
20000mm (Catalog spec)
https://www.pertex.com/fabrics/shield-pro/

*The PU Sosui uses ultralight and thin microporous material, the Pertex Shield Pro. Vaseline, insect repellent, and ethanol-containing substances such as hair creams, cosmetics, and sunscreens may stain the fabric. They may also hinder the water-permeability of the fabric. Visit here to remove the oil stains.

Pertex Shield(PU Shinsui)

The Pertex Shield uses a polyurethane-based hydrophilic and non-porous membrane. Though the membrane has no holes or pores, it has a strong affinity to water, allowing the water to sink into the membrane easily.

In other words, the membrane absorbs the moisture within the jacket and then allows it to evaporate. It works like a towel that absorbs water, and then dries by itself.

The greatest advantage of Pertex Shield is its lightweight: The membrane is non-porous, so the fabric can be extremely thin and light. Our experiment has shown that it quickly lowers the humidity within the clothes immediately after being worn, but the humidity will gradually increase after a while. For this reason, you may feel more humid compared with the Pertex Shield Pro material.

Pertex® Shield

Material:
Pertex Shield (100% NYLON)
Weight: 47g/㎡
Surface: 7d/5f x 7d/5f, ripstop
Linning: 7d tricot
Water repellent finish: C6 DWR

Specs:
Tear strength measured by JIS L 1096 D (Pendulum method)
Vertical: 0.8kg, Horizontal: 0.7kg

Tensile strength measured by JIS L 1096 A (Strip method)
Vertical: 22.8kg, Horizontal: 21.2kg

Breathability measured by KES method
270 or more

Water-permeability tested by JIS L 1099 A-1
5568g/㎡/day (Our measured value)

Water-permeability tested by JIS L 1099 B-1
20000g/㎡/day (Catalog spec)

Water pressure resistance tested by JIS L 1092 B
20000mm (Catalog spec)
https://www.pertex.com/fabrics/shield/

Categorization and Characteristics of Waterproof and Moisture Permeable Material

The materials of waterproof jackets are generally made of multiple layers of fabric, that is, a waterproof and moisture permeable membrane is sandwiched between a water repellent, durable surface layer and an absorbent lining next to the skin. The membranes are roughly categorized into two groups according to the waterproof and moisture permeability mechanism: The hydrophobic, microporous membranes, and hydrophilic, non-porous membranes.

The hydrophobic, microporous membranes have a number of very small holes (pores) that are too tiny for the liquid water (rain) to come through, while allowing the vapor (moisture from your body) to vent. They are made of water-repelling ePTFE (expanded polytetrafluoroethylene, AKA, Teflon) or hydrophobic polyurethane (PU). The most common ePTFE material is the eVent, and Pertex Shield Pro that we adopted. Polartec NeoShell is also a good example of a hydrophobic PU membrane.

On the other hand, hydrophilic non-porous membranes have no pores, so they permeate the moisture by absorbing the vapor within the clothes and evaporating it outside. Pertex Shield that we use, HyVent Flyweight by The North Face, and dri1 by Norrona are all non-porous membranes.

Gore-Tex, the most famous waterproof and breathable material, has a hydrophobic and microporous membrane with a hydrophilic coating. The purpose of the coating is presumably to prevent the contamination that can hinder the membrane’s performance, but due to the coating, it is inferior to non-coated hydrophobic, microporous membranes in moisture permeability. That said, Gore-Tex has many variations and it is probable that each product has a different level of coating depending on the exact specifics of the material.

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Test at the Yamatomichi Lab

We have conducted thorough research on rainwear over a year at our Yamatomichi Lab. The result is available online at the Yamatomichi Journal (Japanese only), full of independent research, experiments and new findings.

#1 土屋智哉(ハイカーズデポ)x 夏目彰(山と道)特別対談
レインウェアのメカニズムや使いこなしについてさまざまな論点が出されました。この対談で提示された疑問がそのままラボのリサーチテーマになっていったと言っても過言ではありません。

#2レインウェア・マーケット分析
市場に存在するレインウェアを多角的に分析し、利用シーンをもとに分類しました。超軽量レインウェアとウインドシェルが用途的に重複するのではという発見もありました。現在では古くなった製品も含まれていますが、この分類軸は未だ有効であると思います。

#3 透湿試験とメンブレンの解説
メカニズムと既存の試験方法について深掘りしました。「疎水性」「親水性」というキーワードが重要性をおびるとわかるのはこの後、実際の実験結果がこの両者で大きく異なることに気付いてからです。

#4 独自検査法による透湿性能試験
ムレた高湿条件での透湿性をはかるべくオリジナルの調査を実施しました。結果にバラツキはあったものの、疎水性素材の優秀さと、ゴアテックスの保温性というメリットが浮き彫りになりました。

#5 電子顕微鏡による組成解析
謎の多い各社の素材をハダカにすべく、電子顕微鏡でアプローチしました。これまでの仮説を深めることができました。

#6 これまでのまとめ
#1~#5までのまとめです。こちらを一読いただければこれまでの流れがわかるようになっています。

#7 同一試験による防水透湿素材の総合評価
レイン素材単体の総合的なレビューです。実験結果をもとに、「疎水性」「親水性」を軸として素材を整理しました。透湿性や保温性、軽量性を高次に満たす完璧な素材はありませんでしたが、総合点のよい高バランスの素材をいくつか特定することができました。

#8 レイヤリングのもたらす効果
レイン素材をレイヤリングした場合の効果をテストしました。メリノウールの優秀さと、速乾をうたっていても蒸れやすいという化繊の弱点が明らかになりました。山と道レインもレイヤリングにはメリノウールを強くおすすめします。

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Size

推奨サイズ/Recommended Size

Unisex
Size XS S M L XL
体重/Weight
kg
42~53 51~61 59~69 67~78 76~85
胸囲/Chest
cm
78~84 80~88 84~95 92~102 100~110

製品サイズ/Product Size

Unisex
単位:cm
Size XS S M L XL
着丈/Length 68 72 74 76 78
身巾/Body Width 50 57 61 65 69
裾巾/Hem Width 50 57 61 65 69
裄丈/Neck to Sleeve 81 84 86.5 88.5 90.5
袖口巾/Sleeve Opening 9.5 9.7 10 10.2 10.5

Please Note

  • The UL Rain Hoody is our ultralight water-resistant rainwear made of ultrathin, water-permeable fabric. Please handle with care as it can be torn or ripped when rubbed against rocks or scratched by spiky branches.
  • The UL Rain Hoody is comfortable when you on the move in a relatively warm environment. However, it is less warm than normal water-resistant jackets or winter hard shells so we strongly recommend you wear a merino wool base layer to keep you warm especially when severe weather is to be expected.
  • In order to maximize the moisture-permeability of the UL Rain Hoody PU Sosui/Shinsui, after-use care is necessary. The performances of the membrane, facing and lining can be impaired by dirt, sweat, and skin oil, or other substances. Please follow the washing instruction of each product to properly wash, dry, and keep it clean. The use of rainwear-specific detergent is highly recommended.
  • We recommend the use of water repellent spray regularly to restore the water repellency of the fabric.
  • The PU Sosui uses ultralight and thin microporous material, the Pertex Shield Pro. Vaseline, insect repellent, and ethanol-containing substances such as hair creams, cosmetics and sunscreens may stain the fabric. They may also hinder the water-permeability of the fabric. Please visit the following link to remove the oil stains:山と道JOURNALS『山と道修理部通信#2 レインウェアの油脂汚れをきれいにする』
  • Because the Pertex Shield has a different moisture permeability mechanism, the PU Shinsui is not stained by Vaseline, etc.

Care Instructions

  • Machine wash, gentle at 30°C.
  • Use Rainwear-specific detergent if available.
  • Wash separately or use a laundry net bag.
  • Tumble dry below 60°C.
  • Do not bleach and do not use fabric softener.
  • Iron on low, covered the pants with a cloth. Do not steam.
  • Do not dry-clean.

Payment

  • We only accept payment by credit card. We currently do not accept payment via bank transfer from overseas accounts.
  • We accept the following Credit Cards: Visa, Master, American Express, and JCB.
  • To download your receipt, please click the link included in the Dispatch Notice, which we will send by email as soon as the items are dispatched.

Delivery

We will ship by DHL for overseas customers (excluding China, Hong Kong, Taiwan, Korea and Russia). For customers in China, Hong Kong, Taiwan, Korea and Russia, we will ship by EMS only. Shipping costs vary depending on your country and region.

Size Exchange

  • Overseas customers who need to change the size of their order, should note that the time needed for shipping will vary greatly depending on your country of residence.
  • We only accept exchanges when the item is unused (except for fitting).
  • If you wish to exchange the size of the item, please contact us within seven days of receiving your order.
  • Exchanges can only be made for the same color in a different size.
  • If the size you wish is out of stock, we will suggest a different color.
  • If the product is out of stock, we may simply have to ship the item back to you.
  • All shipping costs to be carried by the customer.
  • We will only send the exchanged item to you, upon receipt of return shipping cost via PayPal.
  • Please be aware that some countries charge customs duties depending on the price of the item.
  • We are unable to answer any questions on local customs. Please contact your local customs bureau.

Repair

We accept repairs for all of our Yamatomichi products. For inquiries on repair services including patching the holes, repairing with extra components, or fixing the items damaged over time, please feel free to contact us from the “Repair” section of the SUPPORT page.

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