Kosha Base Layers : Thermals Reinvented

From thermals to sweaters and from beanies to socks, Kosha offers all winter wear layers. It wasn’t until one of our customers asked for a Base Layer, particularly for a Marathon in New York. We knew that the traditional wool thermal would not serve the purpose. A category that hadn’t seen a change in decades challenged us to think it over. 

Redefining the base layer:

We started our quest to find out various features that people seek in thermals via an easy tick box format feedback form, distributed through our store.

— We needed something that doesn’t itch, is soft, sweat-free, and odor-free.
— Our bodies can heat up even at -4 degrees so it was necessary to make something that would feel warm and also be able to regulate temperature across various outdoor activities.

We began research to find the most suitable fabrics. Locking in Merino wool, one of the most expensive and finest quality of wool. We wanted to steer away from polyester and found Bamboo suitable because it’s soft and durable. And this is how we arrived at a Merino Bamboo fabric blend. We then tried various compositions of the two to achieve the right thickness.

The redefined quintessential base layer 

We received the first set of samples made of 47.5% Merino Wool, 47.5% Bamboo, and 5% Elastane in April, when it was winter in the Southern Hemisphere. So we sent some samples to adventure and travel enthusiasts in Australia to test the warmth, comfort, and feel of the fabric. It also helped us to know what range of temperatures the thermals were suitable for and also about the wash care problems. Another set of samples was made in bamboo fabric to test styling, the overall look and sizing aspects of the garments.

Features of the future:

Kosha’s Merino Wool Bamoo blend Base Layer ensures that your travel or athletic experience does not freeze you but frees you. 

They were made lightweight for ease in wearing and for reducing baggage weight. Approximately 22% lighter which may not seem like a major figure while reading but it does matter when in use.
— Flat-seam stitching was used to have lesser friction during use.
— Minimal branding by printing the name on the fabric helped avoid irritation. 

A cool warmer:

Once you land at Kosha, you’ll find your size and a color palette that has departed from the usual dull grey to shades of Blue, Dark Green, Beige, Burgundy, Black and Gunmetal. We offer them in regular and plus sizes for Men and Women. We also offer them for toddlers to teens. 

Now you can skip your mid-layer or take off your jacket for a photograph in the snow. Run, trek or mountain climb without a worry. The innovative all-weather Merino Bamboo thermals will keep you warm and dry at -30 degrees and sweat-free and odor-free in warmer temperatures.

Tested across the world: By skiers in Australia and leisure travelers in Canada, ranging from 15°C to -10°C. Kosha’s founder Yuktie has practically lived in these thermals for two weeks of her Mountaineering course that summited Mt.Renok, Sikkim while Sukrit roamed around Himachal, Rajasthan, and Manali at -5 degrees.

Kosha ThermalsNeha and Arindam of @Breaktaking.postcards, wearing the Kosha base layer.

Rebecca wore them from Ladakh to California to the highlands of Kenya.

Abishai beat the chills of 5°C to -10°C  in New York.


We continue to develop and build upon our base layer journey to offer the most useful, durable, sustainable and comfortable travel wear.



Our history goes all the way back to early 50s. Prrem and Aloo Vazirani – an accomplished couple who chased after their wanderlust bug. She was a doctor, he was a businessman, and both were filled with a desire to explore the world.