Warmth
Breathability
Durability
Comfort
Odor Resistance
Sustainability
Fabric(s)
78% merino, 22% polyamide
Fabric weight
150 g/m²
Weight
6.7 oz.
Variations
Half-zip hoody
Pros
Cons
Black Diamond Solution 150
For this season's top models, see our guide to the Best Base Layers.
The Black Diamond Solution 150’s 150-gram, predominantly merino build provides reliable midweight warmth, making it a great option for cool-to-cold conditions. On a resort skiing trip to Grand Targhee, I wore it under an insulated ski jacket in mid-20s temperatures, and it kept me perfectly comfortable—warm but never stifling. Another Better Trail tester layered the Solution 150 under a wind jacket while hiking in blustery Patagonia and found it comfortable throughout the day, whether moving at a steady pace or pausing for trailside breaks.
Compared to a 100% merino base layer with the same 150-gram fabric weight, the Solution’s addition of 22% polyamide (a nylon-like synthetic) makes it slightly less warm but improves breathability and moisture-wicking. This versatility makes it an excellent choice for cool shoulder-season days or as a next-to-skin layer for winter activities. However, it’s less insulating than heavier options like the 250-gram Smartwool Classic Thermal; on the other hand, the merino blend—adept at trapping body heat—can feel too warm in mild temperatures.
I was impressed by the Solution 150’s ability to handle a range of temperatures, both internal and external, and found it more breathable than a 100% merino base layer. While merino naturally wicks moisture and breathes well, it’s also warm and slow to dry—meaning it pulls sweat off your skin but can stay damp. The Solution’s synthetic blend helps mitigate this by drying faster and improving breathability without sacrificing too much warmth. I hiked in the Solution 150 with a wind jacket in mid-50-degree, windy conditions in Patagonia, and it stayed comfortable without building up too much heat. That said, like any predominantly merino base layer, it’s not my first choice for high-output activity, but if you’re keeping your heart rate relatively low, it offers an impressive temperature range.
The Solution 150 is one of the most durable merino base layers I’ve worn, thanks to its NuYarn construction. By wrapping a nylon core with thin merino fibers, NuYarn creates a fabric that is significantly stronger than 100% merino. After multiple multi-day backpacking trips and frequent wear under a climbing pack, my Solution 150 is still hole-free—whereas a comparable 100% merino base layer, like the Smartwool Classic Thermal, almost certainly would have developed holes by now. Pure merino layers tend to pill and thin out quickly with repeated use, especially under backpack straps, but the Solution 150’s synthetic reinforcement makes a noticeable difference. If you love merino but hate how quickly it wears out, this is a serious upgrade.
I really like the fabric on the Solution 150—it’s mostly merino wool with 22% polyamide, which makes it less scratchy against the skin than a 100% merino base layer. It also feels smoother and slightly more structured. Not all merino blends are created equal: compared to the Smartwool Intraknit Thermal (53% merino, 45% polyester, 2% elastane), the Solution 150 has a looser, less skin-tight fit, making it fade into the background more—something I appreciate for all-day comfort. Of course, it’s not as silky soft as a Le Bent merino-bamboo blend, but it’s still cozy, breathable, and comfortable for extended wear.
Despite containing 22% polyamide, the Solution 150 performs just like a 100% merino base layer when it comes to odor resistance. After four days of backpacking, I was surprised that the shirt didn’t smell at all—something that’s nearly unheard of with fully synthetic layers. In comparison, a 100% polyester base layer like the Patagonia Capilene Midweight usually starts to stink after just a day or two. The Solution 150’s merino-dominant blend does an excellent job of keeping odors at bay, making it a reliable choice for multi-day trips where washing isn’t an option.
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Longevity
Choosing durable outdoor gear and keeping it in use for longer is one of the best ways to reduce environmental impact. Our proprietary longevity rating assesses factors like overall build quality, materials, fabric denier, component durability, and real-world performance. A green check indicates that we expect the product to be long-lasting relative to its peers, a yellow check mark indicates average longevity, and a red X indicates a product that may have a limited lifespan.
Responsible Wool
Responsible wool is most commonly certified by standards such as the Responsible Wool Standard (RWS) and ZQ Wool, which promote sustainable land management, animal welfare, and responsible farming practices, though some brands occasionally use other equivalent third-party certifications. A green check mark indicates a product uses responsibly sourced wool, a yellow check indicates the brand sources responsible wool for the majority of its products but does not specify it at the product level, and a red X indicates the product does not use responsibly sourced wool.
Responsible Manufacturing
This criterion evaluates a brand’s commitment to fair wages, safe working conditions, and reducing environmental impact through certifications and programs like Fair Trade Certified, Fair Wear Foundation, Worldwide Responsible Accredited Production (WRAP), and the Fair Labor Association, while also recognizing brands that manufacture primarily in the U.S. or Europe under strict labor and environmental regulations. A green check mark indicates a brand meets our responsible manufacturing criteria, while a red X means it does not.
Recycled and/or Reduced Packaging
Packaging can add significant waste to outdoor gear purchases, so many brands work to reduce its impact by using recycled materials, incorporating Forest Stewardship Council-certified paper products, and minimizing plastic and paper use. A green check mark indicates a brand uses recycled or reduced materials across all of its packaging, a yellow check indicates moderate or limited use of recycled or reduced packaging, and a red X indicates the brand does not make either of these efforts.
Resale and/or Recycling Services
Resale and recycling programs help keep outdoor gear in circulation longer and out of landfills, ranging from trade-in resale platforms that offer store credit to take-back initiatives that recycle products at the end of their usable life. A green check mark indicates a brand offers both resale and recycling programs, a yellow check mark indicates it offers one or the two, and a red X indicates it offers neither.
Carbon Footprint Tracking
This criterion evaluates whether a brand measures, reports, and works to reduce its greenhouse gas emissions using established frameworks such as the Higg Index, Greenhouse Gas Protocol, or The Change Climate Project. A green check mark indicates a brand publicly reports greenhouse gas emissions data, sets clearly defined reduction targets, and uses established tracking frameworks such as Higg or The Change Climate Project. A yellow check mark indicates the brand tracks emissions and outlines reduction goals but provides limited data, lacks science-based verification, or does not clearly report progress. A red X indicates the brand does not appear to track greenhouse gas emissions or provides so little information that its efforts cannot be verified.
Annual Impact Report
Annual impact reports provide transparency and accountability by outlining a brand’s sustainability efforts across areas such as material sourcing, greenhouse gas emissions, waste, water use, supply chains, and packaging. A green check mark indicates a brand publishes a detailed, brand-specific impact report that closely aligns with our sustainability criteria and leaves little room for ambiguity. A yellow check indicates a brand provides some relevant sustainability reporting but lacks detail in key areas or is covered only briefly within a parent company report. A red X indicates a brand does not regularly publish an impact report.
Tester: 6’1” 160 lb.; 38 ¼" chest; 31” waist
Size tested: Men’s Large
I normally wear a men’s Large and opted for the same in the Solution 150. The fit is snugger than other merino base layers I’ve used, particularly in the sleeves, which felt a little short when using the thumb loops. It wasn’t restrictive, but layering it over a standard-sized t-shirt caused the t-shirt to bunch up awkwardly and stick out at the bottom. That said, I don’t want to paint the picture that the Solution 150 is a skin-tight layer. Compared to base layers like the Smartwool Intraknit Thermal or The North Face Summit Series Pro 120, it isn’t nearly as tight—it offers a fitted feel without the second-skin compression of those options. Still, it’s form-fitting enough that I wouldn’t wear it on its own as my first choice. If you prefer a looser fit or want more flexibility with layering, consider sizing up.
REI Co-op Merino 185 ($80): Budget-Friendly Merino
The REI Co-op Merino 185 is a 100% merino wool base layer that delivers natural softness, breathability, and odor resistance. However, it doesn’t match the durability of the Solution 150’s NuYarn blend and is more prone to pilling and developing holes over time. It also has a slightly scratchy feel compared to the smoother, more structured Solution 150. If you’re looking for an affordable, all-natural merino option and don’t mind sacrificing longevity, the REI 185 is a solid choice for midweight warmth. That said, for those who want the best of both worlds—merino’s performance with added durability—the Solution 150 is the clear winner. For a deeper dive, read our REI Co-op Merino 185 review.
Smartwool Intraknit Thermal ($130): High-Output Moisture Management
The Smartwool Intraknit Thermal Merino base layer is designed for high-output activities, blending 53% merino wool with 45% polyester and 2% elastane. Thanks to its body-mapped mesh ventilation, it outperforms the Solution 150 in moisture-wicking and breathability, making it ideal for high-exertion pursuits. Its slim, athletic fit enhances moisture transfer and minimizes bulk, though it may feel restrictive for those who prefer a more relaxed cut. If you need maximum breathability for intense activities, the Intraknit Thermal is a top pick. But for those who want a more versatile, durable, and less compressive base layer for a variety of conditions, the Solution 150 is the better all-arounder. For more, read our in-depth review of the Smartwool Intraknit Thermal.
The merino/polyamide Solution 150 features a sleek and durable face fabric that effectively resists abrasion. However, it’s pricier than most and doesn’t feature any venting, which can prove helpful for active use.
Warmth
Breathability
Durability
Comfort
Odor Resistance
Sustainability
The Merino 185 is REI’s 100% merino base layer. The 185-gram weight is a nice middle ground between light and heavyweight alternatives. However, it’s not as soft as we’d prefer and won’t hold up to heavy use as well as merino-nylon blends.
Warmth
Breathability
Durability
Comfort
Odor Resistance
Sustainability
With a merino-polyester blend and mesh ventilation, Smartwool’s Intraknit Thermal is ideal for fast-paced activities in cold weather. It’s one of the only merino base layers we’ll wear when we plan to sweat. However, the price is high, and not everyone will love the skin-tight fit.
Warmth
Breathability
Durability
Comfort
Odor Resistance
Sustainability
The Black Diamond Solution 150 is a great base layer for those who want the performance of merino without its durability tradeoffs. During testing, its NuYarn construction lived up to its claims, proving significantly more resistant to pilling, stretching, and holes than 100% merino. Hikers, skiers, and backpackers will appreciate its versatile midweight warmth, which works across all four seasons. That said, there are better merino blends for high-output activities (like the vented Smartwool Intraknit Thermal), and not everyone will love the Solution 150’s snug (but not skin-tight) fit. But for a soft, odor-resistant, and breathable midweight base layer built to last through repeated use and demanding conditions, it’s an excellent choice.
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