100% Merino Light
Long Sleeve Zip
¥15,400 Tax included
- Product Story 1
- Product Story 2
- Form and Function
- Where the 100% Merino Light Stands
- Recommended Scenes
- Yamatomichi Lab Base Layer Special Issue
- Naturally Odor Resistant
- Great Moisture Control
- Even Warm When Wet
- Instant Ventilation
- More Durable and Stable Quality
- Why 100% Merino?
- Disadvantages of Wool
- Color Transfer
- Care Instructions
Ventilating 100% Merino
The slim-fit 100% Merino Long Sleeve Zip has a wide zipper opening to the chest for excellent ventilation. It is a perfect base layer for activities in the mountains where temperatures drastically change.
The latest 2022 fabric is the updated version of our proprietary, washable and shrink-proof merino wool, being approximately 10% lighter with 150-155g/m2 in average weight. It is suitable and comfortable even in warm seasons.
Our lineup of 100% pure merino wool products makes your hiking more comfortable as they help to regulate both temperature and humidity and keep unwanted odors to a minimum.
Spirality after the Wash
The fabric will be spirally twisted when it is wet, especially right after the wash. It will be untwisted and restored to a certain extent by the line-dry because of its own weight and downward gravity.
The extent of spirality (twisting) differs in each product, and it can only be recognized after it has been washed and dried. Therefore, if the spirality, twisting, or distortion of the fabric is apparent after the purchase, we will accept a return* and offer a full refund even after washing and wearing.
*For a full refund, please return the item by August 31, 2022.
Made in Akita, Japan
100% Merino Wool 150-155g/m2
YKK #3 Coil Zipper
147g (Size XS)
165g (Size S)
183g (Size M)
197g (Size L)
209g (Size XL)
UNISEX | XS / S / M / L / XL
Product Story 1
Akira Natsume, Yamatomichi Founder
I really love Merino fabrics.
They are almost odor-free even when I sweat, comfortable, and keep the humidity and temperature constant even if I get soaked. Merino wool has so many natural and excellent properties that make it perfect for hiking.
When thru-hiking over a longer period, I really start to feel that I myself am part of nature. It is like my body somehow resonates and links with the greatness of my surroundings.
Deep in the mountains, as I walk, run, sweat, sleep, wake up and walk again, Merino wool is always my choice. For me, it connects my body with nature, and that is why I continue to focus on items made of pure Merino wool without any added synthetic fibers.
I have spent so much time and money developing our proprietary merino fabric. Why? This is all because of my love for merino!
Product Story 2
By Rin Matsumoto and Takahiro Yamamoto
We have updated the 100% Merino Light fabric from the previous 165-170g/m2 to a lighter 150-155g/m2 fabric. In 2021, we achieved a major shift from ply-yarn to single yarn*, improving dimensional stability even after washing. As a result, we had fewer complaints from our customers about shrinkage, however, the earlier version was heavier than we expected and felt a little too hot in mid-summer.
*Single yarn is a single spun yarn, while ply-yarn is made by twisting two single yarns together.
We decided to further improve the 2021 version to create a lighter and more comfortable fabric even at high temperatures during the summer. The lighter fabric naturally doesn’t provide as much insulation, but for us the lighter the better. Read on to learn how we have updated the fabric.
Make It Lighter!
To lighten a fabric, there are two basic options:
- Make the yarn finer
- Loosen the knitting density
The 2021 version used a super fine wool yarn (grade 1/52), and any finer yarn would have been hard to come by and would have been lacking in strength. Hence we decided to explore reducing the weight by loosening the knitting density. This requires delicate adjustments to achieve a good balance of yarn thickness and knitting gauge. We decided to make three prototypes with three different density levels.
All three prototype fabrics were successfully lighter than the 2021 version. The lightest was 135g/m2, which was so lightweight that it was too thin and unreliable. The heaviest was 150g/m2, and it was the closest to the target weight we were aiming for. We decided to proceed with the development based on this 150/m2 prototype.
Our analysis showed that the 150g/m2 prototype fabric performed better in terms of air permeability but let out heat due to the looser density. While this result was expected, sadly, the tensile and burst strength also declined. The decrease in tensile and burst strength due to a looser weave is a physical disadvantage resulting from the weight reduction, but we thought it was essential to make the fabric as strong as possible.
Meeting after meeting with the development team of a fabric manufacturer in Bishu, we decided to increase the twist count of the yarn to make it stronger. Yarn with a high number of twists, or high-twist yarn is generally stronger and less likely to get fuzzy. In addition, we decided to increase the density of the 150g/m2 prototype to enhance the strength.
The next prototype fabric was made of a high-twist yarn with increased density. The weight was a little heavier than the first prototype due to increased density, but it seemed more stable and improved in many aspects. The tensile and burst strength, which was one of the most important factors, was also enhanced. In our test, the prototype performed well in dimensional stability after washing, bringing us closer to our ideal.
Next, to test the durability after washing and drying, we produced more prototypes for testing. After twenty consecutive cycles of both washing and tumble-drying at a low temperature, we confirmed that the prototypes performed well; they were in good shape and stable in measurements.
Spirality: Why and How It Occurred
After the favorable result of the prototype test, we started to get ready for production. We waited for the fabric to be finalized by the manufacturer, but oddly, they didn’t deliver it at the agreed date. We contacted the manufacturer, and they told us that they were trying to do their best to fix a problem of “spirality”.
Spirality is a fabric’s tendency of twisting toward a certain direction. If a spirality issue is noticeable in a T-shirt, it means that the shape of the T-shirt is distorted and twisted.
Usually, three factors can cause spirality: Using natural fibers, single yarn, and jersey knitting. Our fabric ticked all these boxes.
When we created the previous 2021 version fabric, we switched from ply-yarn to single yarn, in which we intentionally reversed the knitting direction so that it counteracts the yarn twists and neutralizes the spirality. This time, however, the twist count was increased to enhance yarn strength; it was probable that the yarn twist was so high that the twisting energy exceeded the knitted fabric’s untwisting tendency, thus the problem of spirality occurred.
We wanted a tumble-dryable fabric, which must have been a challenging demand for the manufacturer because the solution for the spirality issue was hard to find. The mechanism of spirality is as follows: When the wool fabric gets wet during washing and absorbs water, it swells, causing the high-twist yarns to untwist, thus spirality occurs. As the fabric dries, the spirality should be canceled and restored to the original shape, but the problem is that natural drying including line-drying and flat-drying is different from low-temperature tumble-drying in terms of the drying speed and the extent of untwisting. In other words, the natural drying and tumble-drying remove the moisture of the shirt differently, thus it was impossible to achieve an equal balance of twisting and untwisting under both natural drying and tumble-drying.
“This same issue must have been an issue with the prototype too,” we thought. We checked the prototype again but didn’t find the same issue with spirality. Why? It was because we adjusted the balance of twisting and untwisting, focusing on low-temperature tumble-drying instead of line- or flat-drying. In mass production, on the contrary, the fabric manufacturer prioritized natural drying, so low-temperature tumble-drying caused the spirality issue.
If the “high-twist yarn” is causing the spirality issue, our attempts to improve the already knitted fabric will not lead us to a satisfactory solution. The fabric manufacturer did their best to improve the post-production, and the spirality was within the acceptable level of 2 to 3% in natural drying, which was below the generally acceptable standard for spirality of 5%. In low-temperature tumble drying, however, the spirality was unacceptable between 7 to 10%.
Should we label the product “Tumble-dry, low” or should we label it “Do not tumble-dry”? It was a difficult decision because the fabric scarcely shrunk and measurements were stable although the spirality was apparent. Consequently, we decided on “Do not tumble-dry” and recommended line-drying instead of flat-drying so that the fabric would smoothly untwist as it dries.
The degree of twisting and untwisting varies depending on how it is dried. The types of washing machines used are all different and sometimes it is washed in summer, sometimes in winter. We tested wool knitwear made by other companies on the market and concluded that the spirality issue is the fate of natural fibers such as cotton and wool to a more or less extent. We decided to sell the shirt made of this fabric since the spirality is not a disadvantage that affects the functionality or performance, but a characteristic of the fabric’s appearance.
Spirality has been unavoidable since we decided to adopt a stronger yarn. In this development, we realized that it was difficult to make something flawless in every aspect. In the endless journey of manufacturing, what’s important is the balance and priority of achievement. We are now moving on to the next stage of development, believing that the twists and turns will lead to even more sophisticated manufacturing.
Form and Function
Where the 100% Merino Light Stands
Though this product dries slower than general synthetic base layer T-shirts, it is less likely to cause hypothermia caused by the evaporation of sweat or other moisture. In other words, the new 100% Merino Light series focuses on moisture absorption rather than quick-drying, and on thermal insulation rather than cooling properties.
When the temperature changes drastically
Wool is good at maintaining a constant temperature inside the garment, keeping you dry and comfortable even in situations where temperatures can suddenly change.
When worn under an outer shell
Synthetic base layers with low moisture absorption can feel very humid and stuffy. On the other hand, our 100% Merino’s superior moisture absorption properties, will help to keep you dry and comfortable when worn under an outer shell.
When worn for long hours
Synthetic clothes often become smelly relatively early on, even if they are deodorant finished. Wools, on the other hand, naturally eliminate odor when the fabric dries even after being soaked in sweat. This powerful anti-odor performance allows you to keep moving day after day, relatively comfortably without smelling too bad. For details, please visit HERE (Currently available in Japanese only).
When packing capacity is limited
Our Merino wool products can be worn in various situations for long hours without getting too smelly, minimizing the need for extra clothes in your backpack.
Yamatomichi Lab Base Layer Special Issue
In our base layer special issue, we highlight the outdoor base layer clothes. We analyze the materials and review the items of outdoor makers. It is currently available in Japanese only. For details, please visit the following link 『山と道ラボ ベースレイヤー編』.
Naturally Odor Resistant
Wool base layers are chosen by many hikers for the material’s excellent odor neutralizing performance. Some say it’s almost odor-free even after a week of heavy hiking, but we’ll let you (and your friends) be the judge of that…
Great Moisture Control
Wool is great to help you keep warm and cool as it naturally controls the moisture level within the clothes, always keeping you comfortable throughout the year.
Even Warm When Wet
First, when wool absorbs moisture, the thermal phenomenon called “absorption heat” is generated. Secondly, its excellent insulation properties (low thermal conductivity) prevent the body heat from being lowered by evaporation. Also, the crimped fibers are bouncy and retain loft without crushing even when wet.
In addition, wool can absorb more moisture in between the fibers, always keeping the skin dry and comfortable.
Consequently, 100% Merino wool keeps you warm during the action, even in severe weather that makes you wet to the skin.
The front zipper allows for instant ventilation. Features a slim-fit design for base-layer use.
More Durable and Stable Quality
We have focused on using 100% merino wool without synthetic fibers. However, pure merino often triggers caused a lack of strength, yarn breakage, and shrinkage after washing.
We examined the optimal spinning and knitting methods, and our conclusion was to work with single yarn. The fabric uses the high-twist yarn and is pre-shrunk by tumble drying, which is a rare process for merino clothes, making the fabric strong but bouncy.
Our proprietary fabric is produced in Bishu, the production area of wool garments in Japan, in cooperation with the spinning company, fabric factory, dyeing, and processing factory, and inspection organization. We continue our effort to innovate with new products and markets.
100% Merino Wool
Yard count: 1/52
Bursting strength (JIS L1096A): 264kPa*
*The value of the pressure when the rubber membrane tears the fabric as the membrane is continuously pressurized.
Heat retention (JIS L1096A): 17%*
*Energy loss when the fabric is placed on the heat source.
Why 100% Merino?
Wool is a natural material with various unique features such as temperature/moisture control, thermal insulation, and is naturally odor-resistant. All developed by sheep to survive the harsh environment over time.
Merino wool comes from merino sheep and compared to other kinds of wool, merino’s fiber is finer, softer, and less scratchy, and hence even suitable for making underwear and baselayers.
All wool, including merino wool, is cool in summer and warm in winter. It is warm even when it’s wet, and practically odor-free even after many hours of wear.
While many other manufacturers add synthetic fibers to strengthen their Merino fabrics, we wanted to stick with 100% Merino to maximize the natural benefits of pure merino wool. Our merino will keep you dry even when it’s hot and humid and comfortable no matter the climate.
Wool is a natural material with various unique features such as temperature/moisture control, thermal insulation, and anti-odor performance; all of them developed by sheep to survive the harsh environment over time.
Merino wool comes from merino sheep and compared to other kinds of wool, merino’s fiber is finer, softer, and less scratchy, and hence even suitable for making underwear.
All wools, including merino wool, are cool in summer and warm in winter. It is warm even when it’s wet, and practically odor-free even after many hours of wear.
The wool’s fiber is composed of amino acid-based protein, just like human hair and skin. The surface is called the “scale”, which is similar to a fish scale, and the inner part is the “cortex”.
The cortex is composed of ortho-cortex and para-cortex, each with different moisture absorption performance. Because each of them differs in property, the combination of ortho and para cortexes makes the fiber “crimped”.
This crimped structure produces the wool’s unique features such as moisture/temperature control property and thermal insulation performance, avoiding the coldness caused by the sweat.
Disadvantages of Wool
As explained above, wool or merino wool has various features and functions, but it is not flawless.
- Easily absorbs moisture and becomes heavy
Wool can get quite heavy as it is great at absorbing moisture. This also means that wool takes longer to dry than synthetic fibers, but compared to cotton, it actually dries faster.
- Liked by insects
Soft, natural fibers such as wool, cashmere, and silk are prone to damage by insects.
- Easily damaged
The relatively short fibers of wool mean that wool fabrics are easier damaged than synthetic and cotton fibers. However, small holes can easily be fixed with a bit of pure wool and a needle.
- Shrinks easily
Wool generally shrinks easily, even when shrink-proofed. To reduce shrinkage, after the wash, please spread the shirt well to return to the original shape and gently iron it.
When knitted wool fabrics are washed, the material is likely to distort diagonally because the yarned fibers absorb water, swell, and tend to untwist. Consequently, the shape of the shirt may distort slightly with washing.
- Distinctive smell
The wool comes from sheep and you may experience a distinctive animal-like smell coming from your t-shirt when damp. This smell usually disappears after the fabric dries.
The above information was compiled and edited based on the interview with the textile company and the research institute, and the reference book below:
Structure and Physical Properties of Wool, Japan Wool Industry Association, Seni Co., Ltd.
推奨サイズ / Recommended Size
|体重 / Weight
|胸囲 / Chest
製品サイズ / Product Size
|着丈 / Length||61||65||67.5||69.5||71.5|
|身巾 / Body Width||43.5||48.5||51||55||59|
|裾巾 / Hem Width||42.5||47.5||50||54||58|
|裄丈 / Neck to Sleeve||72||78||80.5||83.5||86.5|
|袖口巾 / Sleeve Opening||8.5||9||9.5||10||10.5|
|ファスナー長さ / Fastener Length||22||23||24||25||26|
The above values show the measurement when the item is brand-new and unwashed. It will shrink about 1cm vertically and 1.5cm horizontally after a few washes.
– Due to the difference in the shrinkage tendency, there may be some individual differences in the measurements of the product.
– Tumble-drying at low temperature may cause more shrinkage than when dried by natural drying. The shrunk item will be restored by washing and line-drying again.
– Iron with steam if shrunk after the wash and drying. Gently stretch the fabric while ironing for the best results.
When this shirt in Blue, Mustard, or Navy color is rubbed against white or light-colored clothes during rain or when wet from sweating, the colors may transfer and stain other them.
The fabric will be spirally twisted when it is wet, especially right after the wash. It will be untwisted and restored to a certain extent*.
*The extent of spirality (twisting) differs in each product
- This product is made of highly odor-resistant merino wool, which usually does not require a frequent wash.
- The fabric uses shrink-proof pure merino wool. It is machine-washable by “Gentle Course” or “Hand Wash Course” with gentle water flow.
- When you store the item, use mothballs and/or vacuum storage bags to keep out insects.
- Merino’s fibers are short, and fuzz and pilling may appear, which can be removed by several washes.
For more detailed tips on how to wash, store and restore the shrunk item, please visit the following link (Currently Japanese Only): How to Care the 100% Merino Series
The 100% Merino Light items are machine-washable, but please be careful that the incorrect machine setting or temperature setting may cause shrinkage. Merino wool yarn is derived from a natural short fiber, so the fabric may get fuzzy. The fuzz will decrease over time as you wash the product.
Tumble-drying is NOT recommended for this item, as it may cause twisting and shrinkage. If you choose to use the tumble dryer at your own risk, please note that the temperature setting should be 60℃ or lower. Avoid frequent use of a tumble dryer. If shrunk, wash it first and line dry so that the fabric and restores by its own weight and gravity.
- 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.
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.
- 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.
A natural fiber, merino wool has wonderful properties such as excellent temperature and humidity control and deodorant performances, but it also has a weakness; yarns are likely to break and develop holes due to abusive use and moth eating.
For inquiries on repairing holes or products damaged over time, please feel free to contact us from the “Repair” section of the SUPPORT page.
Holes in merino wool cut-and-sewn products caused by thread breakage or moth bites can be repaired by felting, a technique to patch the hole with the raw wool using a special needle. You can repair by yourself, and Yamatomichi also offers felting repair services using raw wool of the same color as the product.
For more details of felting and how we repair the merino items, visit Yamatomichi JOURNALS 『山と道修理部通信#1 メリノウールの穴を補修する』(Japanese only).