100% Merino vs Merino-Nylon vs Merino-Polyester Blends
Ranking each fabric composition relative to its peers. 1 = most, 2 = middle, 3 = least
| 100% Merino | Merino-Poly | Merino-Nylon | |
| Quickest Drying | 3 | 1 | 2 |
| Most Warm | 1 | 2 | 3 |
| Most Odor-Resistant | 1 | 3 | 2 |
| Most Durable | 3 | 2 | 1 |
| Longest Lasting | 3 | 2 | 1 |
| Softest | 1 | 3 | 2 |
| Lightest Weight | 3 | 2 | 1 |
| Most Breathable | 1 | 2 | 3 |
| Warmest When Wet | 1 | 2 | 3 |
| Most Stretchy | 1 | 3 | 2 |
| Most UV Protection | 3 | 1 | 2 |
| Moisture Wicking | 1 | 3 | 2 |
| Most Affordable | 3 | 2 | 1 |
As you can see, no single fabric composition is strictly better than the others, and how to choose the right blend is largely dependent on your personal preferences and trip-specific context.
What about adding Spandex and Elastane?
Some of the merino wool leggings have a small percent of Spandex (a name brand of the generic elastane) mixed in. This adds stretch and rebound properties to the garment. Knit merino is stretchy by itself, but when overstretched, does not rebound well and gets a saggy look. Spandex counteracts this.
So what’s the downside? Strand for strand compared to Merino, elastane is heavier, less breathable, slower to dry, and less eco-friendly (because it’s a synthetic fabric). That being said, mixing in a few percent Spandex does add a nice dose of comfort to any garment, which can be especially important for use with big movement activities, like climbing. It’s also great on trim-fitting garments, which need to be able to move with your body, and can even create compression. The tighter you like a base layer, the more you should prioritize models with a bit of elastane.
Looser Fits Are Slightly Warmer
If you want to optimize for warmth, don’t size down or opt for compression. A bit of bagginess and looseness is advantageous, in that it creates warm air pockets around you, further enhancing insulation. Whereas tight leggings stretch themselves thinner and leave no dead air pockets to insulate.
Why Heavyweight Merino Leggings Are Frequently 100% Wool
We’ve noticed a trend, which is that most merino wool leggings in the “heavyweight” category, that is ~250 gsm, are comprised of either 100% wool, or nearly 100% wool, whereas lower gsm models have a higher percentage of nylon/polyester/Spandex/etc. And here’s why we think that is:
- Merino wool is warmer than synthetic fibers, and heavyweight fabrics are intended for cold climates, so increasing % of merino wool increases the warmth
- One of the downsides to merino wool is that it is slower drying than polyester or nylon. But in colder climates when you’d want a heavyweight garment, you are less prone to sweating profusely and can temperature regulate simply by slowing down your pace. And if you do get sweaty, merino wool is warm when wet.
- Garments made of 100% merino are less durable than merino-synthetic blends, but garments in the ~250 gsm weight are thick enough to dodge durability issue that thinner garments face, simply by virtue of being reinforced with their own thickness.
