Rating: 5 / 5
Second Update: I have changed the rating back to a 5 because I have been using, and even abusing this baselayer and it not only holds up, but the loose sleeve cuffs pop back into shape on washing. It does not smell, even after a two week test in which I wore it constantly as a baselayer for daily activities and sleeping wear. The torso fit stays constant and it feels great.
Update: After wearing the Patagonia Men's Wool 2 crew long sleeve merino wool top for two weeks it has the precise kinds of problems identified by Kevin who commented below in this review thread. The cuffs get baggy and stretch, they do not stay tight -- or as tight as the capilene top. Therefore, they do not feel all comfy and warm and they allow cold air to circulate up the sleeve when worn without an additional layer. While this may be unavoidable it is critical to the feel and warmth of this base layer and its functionality, so I have reduced its rating to a 4.
This is my first merino wool baselayer. Weighs 6 oz. on my scale, the Patagonia site says it is 3.5 oz.
Specs are at:
All the things being said about wool base layers in the BPL articles sure seem to be true, so far.
1. Light weight puts it in competition weighwise with my Patagonia capilene top, of similar fabric density or weight.
2. Comfort is incredible. Soft, doesn't itch.
3. Construction is superior to my capilene top IMO. It has extra cuffs that fold back and can be extended to cover my hands all the way to my knuckles. The seams cannot be felt; the Patagonia site says the arm pit seams are designed to prevent chaffing as are the shoulders to prevent chaffing from back pack straps.
4. Tested outside at 40 F, low humidity, 4500 ft. elev. it works by itself in light wind without exercising. With a vest, like the Flash vest, or wind shirt I believe it will be warm enough down to 32 or less w/ low humidity and no serious wind when exercising. (Update: Wore it in 22 F air, low humidity, no precip or wind, this morning, with the Flash vest and it worked w/o exercise, bit cool in the arms, but it worked.) There is an article that convinced me to try the wool top here at BPL and a second, edited edition of the article available as a book:
Clothing and Sleep Systems for Mountain Hiking, 1st Edition (August 2002),
by Ryan Jordan, Jim Nelson, and Alan Dixon; at:
Comfort and Moisture Transport in Lightweight Wool and Synthetic Base Layers, by Don Wilson, Alan Dixon, and Will Rietveld; at:
The reddish color is great for me because psychologically its a lot warmer than blue and it means it can be seen easily for safety and avoiding losing it.
This piece is warm indoors and stays comfortable going out into the colder night air with a light wind.
So its rating is a 5 when considering functionality, performance, and weight.