REI Co-op Silk Crew Review

This long-sleeve crew is the definition of ultra-light and is worth every ounce when it comes to adding some serious warmth without extra bulk — think of it as the sleeping bag liner of base layers. Tipping the scales at a mere 2.9 ounces, we challenge you to find a warmer layer at a lighter weight. Beyond its impressive warmth-to-weight ratio, this is a simple base layer top in terms of design and utility. We wouldn't consider this as a versatile, 3-season addition to your wardrobe, but rather an ultra-light powerhouse that should live at the bottom of your ski layering system.

Performance Comparison

Warmth

With an incredible warmth-to-weight-to-thickness ratio, the Silk Crew impressed us well-beyond our initial judgment. At first glance, it is hard to believe that the exceptionally thin, chiffon-like material could possibly be of any use as a technical base layer.

But silk is notorious for its heat-retention — just one of the many reasons this natural fiber has long been considered to make some of the finest fabrics in the world. Worn exclusively underneath a lightweight shell, the combo is perfect for spring ski touring when you want to be warm on that first morning climb, but don't want to have to load up on extra layers.

The Silk Crew is certainly designed to be worn as a part of a layering system, rather than as a single-layer. When the wind picked up on ridgeline trail runs, it easily cut right through this sheer shirt, leaving us wishing we had brought along a lightweight windbreaker shell as backup.

Breathability

Silk, as a natural fiber, has similar absorptive qualities to merino wool — both are naturally hydrophobic, absorbing only about 30% of their own material weight in water. Unfortunately, that's where the comparisons end when it comes to overall breathability.

The thin, single-layer build of the Silk Crew provides no loft to support effective evaporation. On mountain bike rides, runs, and in our home workout, this was the only lightweight layer that was visibly sweat-marked at the end of our testing period. While this layer is designed with some airiness — particularly in places that often pool heat, like the elbows — this extra room is not enough to promote quality airflow.

While it does a nice job on long, slow walks, as soon as we broke a sweat it was hard to dump any of that moisture without stripping off outer layers. This was fine when it happened on a long, spring trail run, but not nearly as reasonable when it came to snowier activities, particularly through the colder winter months.

Comfort and Fit

We're split on the Silk Crew when it comes to comfort and fit. On the comfort-side, this top is luxurious, as to be expected with 100% silk. On the fit-side, the cumbersome and overly simplistic design leaves much to be desired.

As a layer, this top feels like an ultra-soft, second layer of skin. Silk — being so sheer — can be difficult to stitch, so this top is not supported by flat-lock seams or any additional articulation. The material is naturally stretchy, providing solid mobility, and the ultra-thin build means that you won't have to worry about bulkiness or any constrictions when layered.

But for all of its positives in terms of comfort, the Silk Crew has the appearance of a pair of sheer tights turned into a top: uncomfortably shiny, and virtually see-through. The torso has a nice, even fit through the chest, but then becomes floppy around the middle, almost entirely losing its athletic cut. The arms are awkwardly baggy; when standing they sag into the cuffs, and when running they billow behind you. But all of these issues with look and fit practically disappear when covered up — rather than taking it out on the town, our head tester opted to leave this top at the base of his layering kit.

Drying Speed

This is a metric where this layer excels. While other natural fibers, like cotton and wool, tend to retain moisture for a long time when soaked-through, the sheer nature of silk allows it to dry off incredibly quickly.

In our laboratory soak n' dry test, the Silk Crew flat-dried in the sun faster than any other base layer top in our review, beating out its closest competitor by nearly five minutes. This means that on a backpacking trip, you could wash this top at sun-up, and it would be completely dry before breakfast.

Unfortunately, the Silk Crew is a special case where drying speed and breathability actually do not go hand-in-hand. While it dries off well when exposed to airflow and/or sunlight, this top does not perform particularly well in terms of drying off on the body, especially when confined under layers.

Durability

All ups have their downs, and while the Silk Crew is at the top of the charts when it comes to drying speed, it is at the bottom of the barrel in terms of durability. This is not a huge surprise, considering that it is built with such sheer material — this top even looks fragile.

This was one of the very few tops that bore a full hole after our laboratory abrasion test. As a result, we wouldn't plan to wear this out on any rock climbs. However, if treated well — i.e., worn strictly as a base layer, washed on a gentle cycle, and air-dried — we believe this top could hold up for much, much longer than a single season of use and abuse.

Layering Ability

This top is designed to be worn at the bottom of your layering setup, and as such fits remarkably well underneath practically any other article of clothing. It is actually thin enough to comfortably wear underneath a heavier-weighted base layer.

In this sense the Silk Crew has the capacity to act as a sleeping bag liner, adding a boost of warmth without much bulk or additional weight. Natural fibers, including silk, have a tendency to cling to fleece, so this top is designed with rib-knit cuffs that help hold the sleeves in place underneath a mid-layer.

Value

As a fine fabric, you can expect to pay a luxury tax for the Silk Crew. Especially considering the material weight of this top, you may wonder how it could possibly cost as much as it does. But we believe that ounce-for-ounce, this crew is worth every dollar in shaving weight for the ultralight backpacker, or adding warmth for those who tend to run extra cold in the winter.

Conclusion