Field Report: 
Duofold Varitherm Silkweight Base Layers

Product Description
From product packaging: “Duofold Varitherm High Performance Base Layer defines the standard for high activity thermal protection and moisture management. Whether you ski, ride or ice climb, Varitherm base layer will keep you warm and dry. Offered in a variety of weights and fabrics, Varitherm’s performance features are permanent and will last the life of the garment.

Silk Weight garments provide lightweight protection, perfect for layering or by themselves in milder climates. Silver-based anti-microbial yarns help prevent odor by inhibiting the growth of bacteria on garments so they stay fresh.

Varitherm Fabrics wick moisture away from the skin for quick evaporation, keeping you warm, dry and comfortable.”

Test Locations and Conditions
Test Period—Mid-December 2005 to mid-April 2006.

Test Locations—Southwestern US (Colorado, Utah, New Mexico, and Arizona).

Testing Conditions—Testing terrains consisted of: badlands desert, canyon country, forests, and high elevation alpine country. Extreme conditions included: snow storms, strong winds, dust/rain storms, intense sun, low temperatures, and high elevations with strong UV radiation. Temperatures ranged from 15 to 65 F (-9 to18 C), elevations ranged from 4,000 to 12,000 feet (1219 to 3658 m).

How the Base Layers Were Tested—I wore the base layers with different clothing systems, outdoor activities, and activity levels. I wore them by themselves in a sleeping system, and as a base layer with other clothing. When the ambient temperature was warm enough I wore the top by itself as a hiking shirt. However, because of the wintertime test period, most of the time I wore additional layers over the Varitherm Silkweight Base Layers for extra warmth.  

Amount of Use and Activities— The Duofold Silkweight Base Layers were my primary base layers during the test period. During the first two months of testing I wore them on a total of 28 trips totaling 34 days in the activities listed below. In addition, I wore the base layers in camp while winter camping a total of 21 days, and slept in them in a sleeping bag a total of 17 nights. I also wore them to watch a winter parade and to pick up trash along our adopted road section.

Measurements and Data—After each trip I recorded the following data in relation to my comfort in the Duofold Varitherm Silkweight Base Layers: 1) temperature, 2) estimated wind speed, 3) estimated humidity, 4) altitude, 5) precipitation (including what form), 6) clothing system, 7) clothing worn over the base layers, and 8) how well they performed in terms of warmth, utility, and comfort.

Factors Evaluated
Following are the specific factors on which I evaluated the Duofold Varitherm Silkweight Base Layers. In this Field Report, I provide information based on two months of testing.

Closeup of the Duofold Varitherm Silkweight Base Layers, showing the fabric texture and pattern, elastic waistband, and flat seams.

Fabric—100% polyester. The fabric has a lot of horizontal stretch and some vertical stretch. It is tightly woven with a fine vertical pattern (see photo).

Construction and Quality—Excellent. All seams are flat to minimize abrasion.

Sizing and Fit—The base layers are very stretchy, so they have a wide range of fit. The size large top was trim but not tight in the body, but the sleeves barely extended to my wrists. The tail extended below my waist about 6 in (15 cm) when tucked in. For me, a size large-tall top would be a better fit to provide adequate length in the sleeves. The size large bottom fit me very well; it is loose (but not baggy) in the legs and has enough length to cover my ankles. 

Overall, the sizing runs a little small. I recommend that Duofold lengthen the sleeves on the regular top.

Features—The top has a 2 in (5 cm) dropped tail; the bottom has an elastic waistband and a fly.

Measurements—Top (size Large): body length is 27 in (69 cm) in front and 29 in (74 cm) in back, chest is 42 in (107 cm), sleeve length is 32 in (81 cm). Bottom (size Large): length is 41 in (104 cm), inseam is 29 in (74 cm), waist girth relaxed is 30 in (76 cm), and waist girth expanded is 48 in (122 cm). All measurements are relaxed unless stated otherwise.

Articulation—The articulation of the top is good but not excellent. With my arms raised above my head, the sleeves pull back from my wrists about 1 in (2.5 cm); bending over with my arms crossed, the sleeves pull away from my wrists about 2 in (5 cm). The bottom fits looser and does not bind in the crotch area or thighs when I raise one leg.

Usability—The Duofold Varitherm Silkweight Base Layers have a smooth surface, so it is easy to don other clothing over them. For hiking in cool weather I frequently wore another base layer over the Varitherm layer. In camp I wore additional insulation layers over that. I was able to wear the Varitherm top as a single layer while vigorously hiking at temperatures above about 50 F (10 C). The same was not true for the bottom; I could not wear it while hiking unless the temperature was below freezing (32 F/0 C). I mainly wore the bottom for less strenuous activities like ice fishing and in camp. I typically wore both base layers (and other layers as well) while sleeping in a sleeping bag, to keep my bag clean and to extend its warmth.

Comfort—The Varitherm Silkweight Base Layers felt soft and warm against my skin. I wore the top over a broad temperature range (with other layers over it as necessary), ranging from 15 to 65 F (-9 to 18 C), and found it to be quite comfortable. It provides a surprising amount of warmth for its thickness and weight. In warmer temperatures I definitely sweated in it, especially behind my pack, but it always dried out quickly after I stopped.

Performance—For wicking moisture away from my skin, I found the Varitherm base layers to be as effective as other base layers I have tried, like Patagonia Capeline and Ibex Woolies. At low exertion levels and temperatures the base layer remained dry, but at high exertion levels and temperatures they definitely get wet with sweat, especially behind my pack. After I stopped they dried out quickly in about 10-15 minutes. At cold temperatures (below freezing) and high exertion I wore the Varitherm base layer under another base layer and a wool shirt (Ibex Scout Shirt). At cool temperatures (30 to 45 F/-1 to 7 C) and high exertion, I was comfortable and fairly dry wearing the Varitherm under a hiking shirt. With high exertion at temperatures above about 50 F (10 C) I was comfortable wearing only the Varitherm top.

Odor Management—The Varitherm Silkweight Base Layers resist odors very well. On three extended trips I wore the base layers continuously for five days or more. When I got home a sniff test revealed a moderate body odor, but no foul smell reminiscent of polypropylene underwear.

Weight—At about 10 oz (283 g) for the suit, the Varitherm Silkweight Base Layers are quite light. They provide a lot of warmth and utility for their weight, and are suitable for ultralight summer backpacking.

Durability—After 34 days of wear the base layers show no signs of pilling or wear. The bottom has one snag so far.

Versatility—I found the Duofold Varitherm Base Layers appropriate for a variety of outdoor activities in cold weather.

Cleaning—Washing instructions are: “Machine wash cold with like colors, do not bleach, no fabric softener, tumble dry low, do not iron”. I have machine washed the base layers several times so far, with no problems with shrinkage or fabric deterioration.

Acknowledgement
I would like to thank Duofold and the BackpackGearTest Group for selecting me to participate in this test.

Will Rietveld