The world's most in-depth and scientific reviews of gear

How We Tested Base Layers

Thursday April 23, 2020

Testing these base layers in real-world situations, as well as specific tests conducted in our lab, are what allow us to provide you with such in-depth reviews. From being dragged up chimneys on desert towers to skinning up volcanoes in the Pacific Northwest, we run these tops through the gauntlet. Below is how we test for each metric.

Canyoneering in Utah  the Patagonia Capilene Air breathed well keeping us from overheating in temps in the 60s but didn't stand up to dragging it through sandstone slots.
Canyoneering in Utah, the Patagonia Capilene Air breathed well keeping us from overheating in temps in the 60s but didn't stand up to dragging it through sandstone slots.

Warmth


This one is simple. We wear them in really cold conditions. Alone and part of a layered system, we see how efficient they are at keeping us warm when temps drop into uncomfortable ranges.

Taking a breather from the lung bursting skinning in frigid dawn temps.
Taking a breather from the lung bursting skinning in frigid dawn temps.

Breathability


We use a combination of real-life experience as well as a regulated test within the lab for this metric. We skinned up Mt. Hood, hiked steep talus cones to climb desert towers, pedaled steep mountain biking trails, and ran winding mountain trails in Colorado. In the lab, we tested each top, one at a time in a temperature-controlled, indoor environment — we worked up a sweat with the same short but rigorous exercise routine. We then timed how long it took for our skin and the inside of our shirts to dry after stopping.

Breathing it out up a classic front range climb before a heavy snow is forecasted to start in the next few hours.
Breathing it out up a classic front range climb before a heavy snow is forecasted to start in the next few hours.

Comfort & Fit


We wore them a lot, and with an extremely critical eye. We looked at the comfort of the fabric of each layer next to the skin. We compared the way they fit on testers of different body types, looked at the stitching patterns and features that allow them to move with us and keep from exposing our bellies and backs. The length of the torso and arms were recorded, how comfortable the neck hem was, and the stretchiness of fabric as well as specific features like a drop-tail hem, tapered arms, and thumb loops. We critiqued how they formed to the body, if they bunched up or were uncomfortable in any way while being active, and observed if they were itchy at all, especially when working up a sweat. Through heavy use, a few climbed their way to the top of the comfy list as testers found themselves wanting to wear them all the time.

Coffee and oatmeal - two things you don't leave your bag before having in your hands. The Rab Merino+ 120  the perfect fit and top for crisp fall nights in the southwest. We loved the thoughtful design and fit of the Rab.
Coffee and oatmeal - two things you don't leave your bag before having in your hands. The Rab Merino+ 120, the perfect fit and top for crisp fall nights in the southwest. We loved the thoughtful design and fit of the Rab.

Durability


This was another combo of observation while wearing and playing in them as well as a controlled test in the lab. We beat the heck out of these things- dragging them up desert towers, scraping through slot canyons, and bushwacking into the night. We tested to see how they held up in all of these conditions. We also sent them through wash and dry cycles to see how they held up in what tends to be the environment that breaks down fine fabrics the fastest.

Putting the Icebreaker 200 Oasis to the test dragging it up a squeeze chimney on an obscure desert aid climb. Being 100% merino wool  we were impressed with the Oasis. Still not as durable as the synthetic Arc'teryx Phase AR but it stood up well to the abuse.
Putting the Icebreaker 200 Oasis to the test dragging it up a squeeze chimney on an obscure desert aid climb. Being 100% merino wool, we were impressed with the Oasis. Still not as durable as the synthetic Arc'teryx Phase AR but it stood up well to the abuse.

For our lab test, we took a section of the fabric at the elbow and vigorously drug it back and forth against a 1-foot piece of rough and textured granite to see how the fabric held up to abrasion. This test very clearly gave us an idea of what fabrics would stand up to abrasion over time and which ones were simply not built for it.

We enjoyed living in this top for days at a time  whose Merino-blend helped fight off stink... but not quite as long as other full-wool competitors.
We enjoyed living in this top for days at a time, whose Merino-blend helped fight off stink... but not quite as long as other full-wool competitors.

Drying Speed


As we've expressed before, the time a base layer takes to dry while next-to-skin and the time it takes to dry away from a body are significantly different. To test a layer's ability to do both, we recorded and noted each tops ability to dry while we wore them especially during our testing for breathability - working up a sweat in high-energy activities like mountain biking on warm fall days, climbing in the desert sun, and skinning in not the coldest conditions.

To test the dry time of the fabric completely saturated and laid, we soaked them thru and laid them all out at the same time to dry. Checking them and recording the time it took them to feel dry on the surface as well as dry completely. The significance of this test wasn't necessarily in the specific times it took them to dry but how they dried compared with one another.

Tops during the dry speed test.
Tops during the dry speed test.

Layering Ability


We incorporated each top into any and every layer combination we could imagine. We observed how they felt against the skin with layers of different types and fits worn over the top. We layered tight and sticky technical fleece mid layers, wool sweaters, slick nylon down jackets, and tacky synthetic insulating layers like the Patagonia Nano Air or R1. Any combo we could think of, we tried. We observed if the sleeves bunched up, if they felt bulky or restrictive at all, if they were itchy, if they fit tight or uncomfortable, and how much static electricity they built up.

By putting each base layer through extensive and exhaustive testing and observation across these metrics, we rated them all for each metric to aid in bringing you the most detailed and helpful review out there.

A handsome layering system with the REI Co-op Merino as the base  Patagonia R1 for a mid layer and the Outdoor Research Transcendent Down Hoody as the outer insulating layer.
A handsome layering system with the REI Co-op Merino as the base, Patagonia R1 for a mid layer and the Outdoor Research Transcendent Down Hoody as the outer insulating layer.