The best insulating base layers from RRL, Relwen, the Real McCoy’s, and more.
Like the humble T-shirt, the thermal shirt began as underwear. Typically knit from cotton in a waffle-pattern that more effectively trapped heat and wicked away moisture, it was issued to U.S. Army soldiers fighting in winter conditions during World War II and worn below their standard kit as an insulating base layer.
The thermal shirt can play much the same role today, as its cotton fabric is breathable and soft enough to be worn directly against the skin, and is typically designed to fit below shirts, sweaters and jackets. But much like the cotton tee, it’s also managed to break out of the underwear category to be worn as a first-and-only layer on its own.
Merz b. Schwanen Diamond-Patterned Cotton Thermal Longsleeve
There’s a vintage sensibility to much of what Merz b. Schwanen, which was originally founded in 1911 to make workmen’s shirts and underwear, produces today. That includes its long-sleeved cotton thermal, which has a unique diamond-patterned structure and was modeled after an antique find.
- Eric Twardzik / Robb Report