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Reviews > Clothing > Base Layers and Undies > tasc Performance Bamboo Merino SS Shirt > Test Report by Ray Estrella

tasc Performance Bamboo+Merino Base System, short-sleeve cre
Test Series by Raymond Estrella

INITIAL REPORT - June 23, 2012
LONG TERM REPORT - October 28, 2012


NAME: Raymond Estrella
EMAIL: rayestrellaAThotmailDOTcom
AGE: 52
LOCATION: North Western Minnesota, USA
HEIGHT: 6' 3" (1.91 m)
WEIGHT: 225 lb (102.00 kg)

I've been backpacking for over 30 years, all over California, Minnesota, and many western states. I hike year-round in all weather, and average 500+ miles (800+ km) per year. I make a point of using lightweight gear, and smaller volume packs. Doubting I can ever be truly ultralight, I try to be as light as I can yet still be comfortable. I start early and hike hard so as to enjoy the afternoons exploring/chilling. I usually take a freestanding tent and enjoy hot evening meals. If not hiking solo I am usually with my brother-in-law Dave or my twin children.


The Product

Manufacturer: Thrive NP
Web site:
Product: Bamboo+Merino Base System, short-sleeve t-shirt
Size tested: XLarge
Year manufactured: 2012
MSRP: $28.00 (US)
Weight listed: N/A
Weight measured 5.8 oz (165 g)
Color tested: Black

There's a shirt on my floor...

Quick & Dirty Nitty Gritty

The tsac Bamboo+Merino shirt may be the stretchiest shirt I have ever owned. It has great range-of-motion and does not bind, bunch or ride up while in motion. But it is easily the warmest wool blend shirt I have ever worn too. The athletic cut (read "tight"), materials, and color conspire to make this shirt unbearably hot for summer in my part of the world, or really anywhere that the sun is shining. I can't wait to use it in winter though. Please read on for the details.

Product Description

The tasc Performance Bamboo+Merino Base System, short-sleeve crew t-shirt (hereafter called the tasc or crew) is a short-sleeved, crew-neck t-shirt made by Thrive NP. Thrive's web site has no information about the shirt and the box it came in only has a little. Coming in at the company's Level A insulation rating, it is meant for use in "All Weather, All Conditions, and Intense Activity". I plan to use it for backpacking and day-hiking.

The most interesting thing about the tasc shirt is what it is made of. According to the screen-printed label inside the collar it is made from 30% merino wool, a staple of my backpacking shirts as I like its properties. 5% is listed as elastane, which is a generic name for Spandex-like fabrics, known for its stretching ability. But the interesting number is what they say is "65% viscose from bamboo". As viscose is a liquid this more accurately should be stated as being "65% rayon, made from bamboo derived viscose".

The fact that bamboo is used, instead of the common wood-pulp, is what gives this shirt something extra to crow about. Bamboo is naturally anti-fungal and anti-bacterial, plus is reported to resist harboring odors in the first place, so this fabric should work well with the wool, another material known for its odor fighting abilities. Bamboo fabric wicks better and is more breathable than wool also.

The blend that tasc is using feels noticeably smoother than my 100% wool shirts and similar to my wool/synthetic blends. It has much more stretch (and recovery) than any of them.

The tasc shirt is very well designed for active life-styles. It uses raglan sleeves which keeps the shirt from having a seam on the top of the shoulder, a common pressure point when carrying a backpack. The underarms are gusseted, allowing greater range-of-motion and freedom of movement, with less bunching of the fabric. All of the seams are serged so as to lay flat.

As I mentioned earlier it has a tag-less design with the info normally hanging out the top of my collar screen-printed inside. Here in tiny symbols are the only laundering instructions. (The same symbols are printed on the end of the box it came in too, but nothing in English, something the company may think about providing.) They decipher as Machine Wash warm, No Machine Dry, No Dry Clean and Cool Iron only.

About the only thing I can complain about is the color and it is more of a seasonal thing. Mosquitoes, which we are known for in Minnesota, are attracted to dark colors plus they are just hotter to wear while hiking in the summer sun, so a black shirt is not my normal choice this time of year. But I will suck it up and go for it. Tomorrow in fact! But for now this is it for my Initial Report.


Field Conditions

Sweating at Goose lake

I have used the tasc shirt on four backpacking trips, and one day-hike in Minnesota (MN). The dayhike was a bushwhacking trip through the woods that border the Red River of the North on private property outside Halstad, MN looking for a black bear that had torn up an old farm house. The temperature was around 85 F (29 C) and it was quite humid.

Next were two buggy, wet overnighters in Chippewa National Forest using the North Country Trail (NCT), Woodtick Trail and the Goose Lake hunter trail system. It was very hot and humid from all the standing water. Temps up to 85 F (29 C). The picture above was taken at Goose Lake.

Next was a three-day trip to Lake Bronson and Old Mill State Parks spending a night at each. The first day was very hot; hitting 88 F (31 C), the next was a little cooler. The picture below is of the World's Largest Jack Pine in Lake Bronson State Park.

You don't know Jack Pine...

Then I did a deer fly infested overnighter at Smoky Hills State Park. 93% humidity and a high of 83 F (28 C) made for a pretty sticky hike.

Last summer use was on a 15-day road trip to the Outdoor Retailer Show in Salt Lake City with five days of hiking before it and two days after it. First I took it to Lake Sakakawea State Park in North Dakota, the western terminus of the North Country Trail. I hiked a section of the NCT, and two trails in the State Park and camped by Lake Sakakawea. It was hot and muggy, 81 F for a high and only 67 F for a low (27 - 19 C) with 76% humidity. The next three days (two nights) were spent hiking on the Maah Daah Hey Trail in Sully Creek State Park, Theodore Roosevelt National Park South Unit, and the Little Missouri National Grasslands. It too was very hot with temps from 92 down to 55 F (33 - 13 C) and humidity of 68%. Two days of day-hiking in Montana saw the shirt used on the first day. Finally on my way back home I hiked more in Theodore Roosevelt National Park (TRNP) and just outside of it on more of the Maah Daah Hey Trail. Here is a picture crossing the Little Missouri River on the Maah Daah Hey.

Crossing the Little Mo

I put the shirt away to wait for fall. At the end of September I took it on a long California trip that saw a 2-day backpacking trip in the southern Sierra Nevada, and 5-day backpacking trip in the northern Sierra Nevada, and a day-hike and 2-day trip in the Angeles National Forest. There was a total of 136.5 miles (220 km) with 23575 ft (7186 m) of gain, in temps that ran from 31 to a ridiculously warm for that time of year 90 F (-1 to 32 C). Almost all of it was on the Pacific Crest Trail (PCT).


The tasc Bamboo+Merino shirt has been an interesting one to test. Unfortunately the time of year really conspires against it as this blend of rayon and wool is easily the warmest short-sleeved shirt I own.

The shirt is pretty tight. It is cut like some of my old rock climbing shirts. (In fact with the stretch and the under-arm gussets this shirt would be great for that use.) There is no drape to the cut and it fits pretty tight around my arms, chest and shoulders. The stretch of the fabric saves it from being uncomfortable though as I have no binding from it. One bad thing about it being tight is that it allows biting flies to bite right through the shirt.(The big species like deer fly, stable fly, and horse fly, the first two of which I have dealt with a lot during this test.) I am writing this the evening that I came back from my last trip and trying not to scratch the three deer fly bites on my shoulders and upper bicep that were given me while hiking the first day. (I hiked back to the car the next day in a different shirt.) Here is a shot at Elbow Lake on that trip.

Hot and bitten at Elbow Lake

The tasc Bamboo+Merino is warm. When I take off on a backpacking trip I dress in my hiking clothes as soon as I get up, and then pack my backpack, have some coffee and maybe eat something. I start sweating in my house within minutes of donning the tasc shirt. While this happens with other shirts I own, it is only the winter-weight ones that do so, never the summer-weight shirts. As I have summer shirts that are 100% wool and wool synthetic blends I can only attribute this to the cut and the bamboo-derived rayon in the fabric blend. I even weighed my normal summer shirts to find that the 100% wool ones are heavier than the tasc, so it is not that there is more (thicker) material.

Then there is the color. In winter I love black for all my clothing and probably 90% of my winter baselayers and shirts are that color. But I do not own a single black summer-weight shirt, long or short-sleeved. I would rather reflect the sun at that time of year, not attract it. Well, the only color this shirt is made in is black at this time, so I test what I get. (I found this out by trying to purchase another shirt myself in a different color, no go.)

It has been very hot and sweaty hiking in the tasc shirt. The worst was the trip to Lake Bronson State Park as the trails are exposed, unlike the tree-covered trails in most of my other locations. That trip ended up with twice the distance covered that I planned on because I could not get to the river for water on the trail and had to go all the way back to the trailhead on the lake. (Twice as I had my Water Tank fall and pop open losing 6 L of precious water.) This is from the Hiking Log I keep of each trip which I write as soon as I get home while things are fresh in my mind.

"It was killer hot in the black t-shirt, plus the wool/rayon blend is hotter anyway. I tried getting it wet when I got water to see if it would be cooler to hike back in. No way. It turned into a portable steam-room. I had to take it off and hike shirtless."

On the bright side the material blend does a great job of wicking all the sweat I produce in it. I often notice the surface is quite wet. In a less humid area this may evaporate faster, but here much of it sticks around. I carry a long-sleeved light-weight shirt to change into at camp each afternoon to keep the mosquitoes away. (It is treated with permethrin.) I make a point of rinsing the tasc shirt out each day after changing. It seems to rinse clean pretty well, and it dries fairly fast. It is almost always ready to go in the morning. Here is a picture of me rinsing it out in Gut Lake and of it drying at my camp on the South Branch of the Two Rivers.

Laundry time

It is holding up well to the use so far. I snagged it a few times bushwhacking but nothing happened to it. All the rinsing and wringing out have not made it misshapen or started any seams unraveling. It still looks great with at least 27 days of hard hiking in it.

After letting the shirt sit for a month I pulled it back out for my annual fall backpacking trip(s) with my brother-in-law Dave. As it has snowed on all but one of the past nine years I figured the tasc Bamboo+Merino shirt would be great on it. Well Mother Nature gave us a warm surprise. While the temps did get low at night they warmed up considerably in the days and we never saw any precipitation. The shirt was great starting out in the morning when it was an average of 34 F (1 C) but as soon as the sun came up I was back to broiling in the tasc. I had to rinse the sweat salt out of the shirt each night when I could. (Two of the nights were at waterless locations.) Here is a shot of it worn on the PCT in Sequoia National Forest.

Sweating in southern Sierra

We just got our first snow of the year here in Minnesota. Winter is here and I plan to use the tasc Bamboo+Merino as my regular baselayer as long as the temps stay below freezing. But I will never use it for 3-season use again. It is just much too warm. I highly suggest that tasc change the All Climate, All Weather description. This concludes the Long Term Report of the tasc Bamboo+Merino shirt. My thanks to thrive NP and for allowing me to try it out. I leave with a shot of it worn crossing Middle River in northern MN.

Middle River

This report was created with the Report Writer Version 1.5 Copyright 2012. All rights reserved.
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