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Patagonia Capilene Cool Merino Long Sleeve Review

An uber-lightweight Merino blend whose top-notch performance is unfortunately undermined by silk-like durability
Patagonia Capilene Cool Merino Long Sleeve
Photo: Patagonia
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Price:  $69 List
Pros:  Lightweight, next-to-skin softness, natural odor resistance
Cons:  Silk-like durability, sheer-like translucency
Manufacturer:   Patagonia
By Aaron Rice ⋅ Review Editor  ⋅  May 27, 2021
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  • Warmth - 25% 5
  • Breathability - 20% 9
  • Comfort and Fit - 20% 9
  • Drying Speed - 10% 8
  • Durability - 15% 3
  • Layering Ability - 10% 7

Our Verdict

The Patagonia Capilene Cool Lightweight has been a fan-favorite for years now, and this well-loved top gets an all-natural upgrade with the Capilene Cool Merino Long Sleeve. Though it falls at the extreme end of the warmth-and-weight spectrum, this uber-lightweight base layer is at the top of the charts relative to thermoregulation and athletic performance. Combined with the fact that the merino wool/recycled polyester blend is unbelievably soft, this is a nearly ideal next-to-skin base layer regardless of season. Though it, unfortunately, falls flat in terms of durability, with the right wear and care, the Capilene Cool Merino is in the running for our favorite lightweight base layer for high-output activities.

Our Analysis and Test Results

The uber-lightweight, 4.9-ounce Capilene Cool Merino is spun from a beautiful blend of 65% RWS-certified merino wool and 35% recycled polyester. The Responsible Wool Standard (RWS) helps "ensure protection both for the animals that supply it and the land they graze," and the recycled polyester is recovered from melted down plastic bottles. Though care for this delicate top even exceeds that of other full-merino layers, rest assured knowing its value rests in both performance and the accountability of its production.

Performance Comparison

Long mountain runs are a specialty of this ultra-lightweight top...
Long mountain runs are a specialty of this ultra-lightweight top, which excels in terms of comfort and breathability.
Photo: Jill Rice


Just like its predecessor, the Patagonia Capilene Cool Merino Long Sleeve helps keep you warm by keeping you dry, rather than adding much insulation. As a stand-alone layer, it will barely hold up to a cool breeze on a warm summer evening. But worn next-to-skin underneath a properly layered kit, the majority Merino wool composition allows it to deftly wick up and evaporate away moisture before it even accumulates. So while this layer falls at the extreme end of the weight-and-warmth spectrum, its power lies in the ability to thermoregulate.

Though not necessarily our first choice for frigid, mid-winter...
Though not necessarily our first choice for frigid, mid-winter temperatures, this base layer is ideal for long days and steep couloirs under spring conditions.
Photo: Jill Rice


Warmth will vary as a result of material weight, but so does breathability, and this attribute is a particular strength of the Capilene Cool Merino. Blended merino/polyester tops seem to strike a special balance that allows a base layer to access the best parts of each material — the wool fibers efficiently wick sweat and moisture away from the body, and the less-absorbent polyester makes quick work of evaporation. The two work seamlessly in concert while you continue to work up a sweat, and yet, seem to stay miraculously dry despite the length of your trail run. Whether it's skinning uphill in the middle of winter or running cross-country through the height of the summer heat, based on its performance and weight, this ultra-lightweight base layer is ideally suited for high-exertion activities.

This top is great for long cross-country rides, especially when...
This top is great for long cross-country rides, especially when paired with a lightweight, equally breathable jacket like the Patagonia Houdini Air.
Photo: Jill Rice

Comfort and Fit

The Capilene Cool Merino is the type of top you never want to take off. Unparalleled next-to-skin comfort, combined with the natural odor resistance of Merino make this the go-to base layer for hut trips. You can wear it all day on the mountain, to hangout après, into bed as pajamas, and then back out the next day for more adventure — rinse and repeat for days in a row without it becoming greasy or salty.

Click to enlarge
Click to enlarge

Comfort is top-notch, but for some, the fit may be more questionable. As a lightweight base layer, this slim top is supposed to be form-fitting. The natural stretch of Merino plus side vents — slits in the bottom side hem of the shirt — even afford a more versatile fit to accommodate different body types. However, the sheer quality of the fabric makes it rather translucent — at least in the lighter colorway we tested. This fact is less relevant when worn as a base layer, but quite apparent when worn as a stand-alone shirt.

Though this may not be an issue for many, we were more hesitant to...
Though this may not be an issue for many, we were more hesitant to wear this as a standalone top due to its sheer, see-through quality (note our tester's tattoos showing through).
Photo: Jill Rice

Drying Speed

Savvy readers may have already reached a conclusion regarding drying speed. So it will come as no surprise when we disclose that the Capilene Cool Merino is one of, if not the fastest, drying shirts in this review. Combining the benefits of quick-drying polyester, the natural hydrophobia of Merino wool, and the 139 g/m² fabric weight, the result is a base layer with a practical aversion to moisture absorption. In our air dry test — which simulates handwashing and then flat drying in the sun — this uber-lightweight top was essentially dry in 30 minutes, with just a few damp spots at the thicker intersection of the overlocked seams. This makes the Cool Merino Long Sleeve a great option for those going on an expedition or planning extended backcountry trips.

Not only does this top air-dry incredibly quickly, but the design...
Not only does this top air-dry incredibly quickly, but the design includes a loop for easy hanging (which also keeps this top from developing odd stretch points.)
Photo: Jill Rice


You may be wondering why, for all of the accolades we've showered on this shirt, it ranks so low in this review. There is a simple answer: lack of durability. The Merino-polyester blend is so sheer that it is actually silk-like, and as a result, unfortunately has silk-like durability. After a few weeks of wear underneath a pack, the overlocking seams begin to fray, particularly along the drop-tail hem, an area that often takes a beating when it comes to abrasion. But even with proper care — cold-water washing and air-drying — the many of the seams, from the wrists to the collar, quickly appear worn. Our tried-and-true abrasion test is the final evaluation, which the Capilene Cool Merino abruptly failed, first piling and then rubbing completely through in less than 30 seconds.

Durability is really the only downfall of this top, which scores...
Durability is really the only downfall of this top, which scores highly in every other aspect. Not only did it wear through quickly in our abrasion test, but multiple seams began to drop after only a few weeks of wear.
Photo: Jill Rice

Layering Ability

Like many other thinner, lighter-weight models we tested, the Capilene Cool Merino pairs well with practically any other garments as a primary base layer. It is even possible to pair this top with heavier-weight base layers for extra warmth in the depth of winter. But where this layer really shines is on late spring ski mountaineering missions, where you may need to layer up high up in the alpine, but want to keep it minimal on approach and egress. While it would add an imperceptible touch of weight, simple thumb loops — similar in design to the hanger loop — would only improve the ability to pull on sticky fleece mid-layers over this Merino-blend base.

This thin, lightweight top layers easily under most mid- and...
This thin, lightweight top layers easily under most mid- and outer-layers. It pairs particularly well with windbreakers, as a lightweight alternative to cut the chill of the shoulder seasons.
Photo: Jill Rice


Weighing value against durability, we fear that this layer may wear out a bit too quickly considering its price tag. Though it may be a bit on the expensive side when compared directly to other lightweight competitors, one must recognize that the majority of those are fully synthetic base layers. And when pitched against comparable 100% merino wool tops, or even merino-blended options, the Capilene Cool Merino is much more reasonably priced. Considering the responsibility of its production and capability of its performance, this top is well worth the investment.

Even though there are lighter (and stronger) synthetic options, this...
Even though there are lighter (and stronger) synthetic options, this is easily the lightest weight merino-blend we have yet to test, and it performs exceptionally within its wheelhouse.
Photo: Jill Rice


If Patagonia can improve on the durability of this sheer top in the future, the Capilene Cool Merino Long Sleeve will easily be catapulted to the awards circle. Its ability to thermoregulate is nearly unparalleled, and as a versatile merino-blend that is naturally odor averse, we see very little reason to ever take this top off.

Long, springtime slogs in and out of the mountains are the perfect...
Long, springtime slogs in and out of the mountains are the perfect for this lightweight base layer, which does a great job of thermoregulation through a wide range of tempeatures.
Photo: Jill Rice

Aaron Rice

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