Your base layer is shedding plastic. Here's how to shed less.
Have you tried wearing a merino layer for more than 10 days without washing it?
If not, try — and save the laundry water 
Base layers and t-shirts sit against the skin, so they get washed more than anything else we own — in Singapore's heat, usually after every single wear. That is where a large amount of plastic enters the water.
Washing synthetic clothing releases plastic microfibres
Researchers at the University of Plymouth washed 6 kg loads of synthetic fabric and counted the fibres released. A single wash produced roughly:
- 728,000 fibres from acrylic
- 496,000 fibres from polyester
- 138,000 fibres from a polyester-cotton blend
Napper & Thompson, Marine Pollution Bulletin, 2016.
Most performance base layers are polyester. They are washed more often than almost anything else in the wardrobe, and the fibres they release are too fine for most wastewater treatment to catch.
Where the fibres end up
A survey of shoreline sediments across six continents found that polyester and acrylic made up around 79% of the microplastic fibres recovered, with the highest concentrations near wastewater outfalls.
Browne et al., Environmental Science & Technology, 2011.
Merino needs less washing
Merino is known for resisting odour even after long periods of wear. The fibre naturally slows the bacteria that cause smell, so a merino layer can be worn for days before it needs a wash.
Fewer washes means less water, less detergent, less energy, and fewer fibres leaving the machine.
Merino is a natural fibre, so what it sheds is not plastic. A high purity merino base layer sheds less plastic than a polyester one, and needs washing far less often in the first place.
The t-shirt is the way in. The base layer is the system.
A merino tee is how most people meet the fibre. It is the same wool in the lightest weight, cut as an everyday shirt — and for Singapore that is often all you need.
The range runs from there:
- Short-sleeve — daily wear, tropical hiking, travel days
- Long-sleeve crew — sun cover, air-conditioned offices and flights
- Long-sleeve half-zip — a true base layer under a fleece or down jacket, with a zip to dump heat on the climb
- Leggings and tights — the layer most people forget until the first cold morning
Same fibre, same odour resistance, different weights and cuts for different jobs. That is why the base layer, not the t-shirt, is the piece worth getting right.
We carry icebreaker merino base layers in men's, women's and kids' sizing, alongside Montbell ZEO-LINE. Smartwool covers merino socks and Active Ultralite tees.
How merino handles heat and cooling down
Researchers at North Carolina State University compared 100% merino with polyester, cotton and viscose over four years, using lab testing, sweating manikins and human trials in a climate-controlled chamber.
While participants were working hard, all four fabrics performed much the same. The difference showed up after they stopped: wool kept them comfortable through the cool-down, with less of the clammy chill you get stepping into air-con after a hike.
Abedin & DenHartog, Fibers 11(5):47, 2023 (doi:10.3390/fib11050047) and Textile Research Journal 95(17–18), 2025 (doi:10.1177/00405175241291213). Funded by Australian Wool Innovation.
One lightweight layer, from Singapore to the mountains
Lightweight merino packs down small and weighs almost nothing, which is why it is the fibre people travel with. One tee and one long-sleeve cover a Japanese ridgeline, a teahouse in Nepal and the flight home — no suitcase full of spares, and nothing to wash along the way.
The same pieces work at home. In lightweight weaves merino is cool and breathable enough for daily wear in Singapore, then layers under a fleece or a down jacket when the temperature drops. Wear it for days. Wash it less.
Choosing your base layer
Check the label. Some styles are close to pure merino; others blend in nylon or elastane for durability and stretch. More merino means better odour resistance. More synthetic means a tougher, faster-drying garment that will shed some plastic.
Then choose by weight. Lighter fabrics suit the tropics and high-output days. Heavier fabrics hold more warmth for cold-weather travel and for sitting still at altitude. If you are buying one piece, buy the weight that matches where you are going, not where you live.
Watch: merino next to the skin in Singapore weather
The first of two videos with Thomas Ong 王沺裁 on icebreaker merino suited to Singapore weather. In Mandarin.
与隔壁老王合作的两个视频。这是第一部，介绍了适用于新加坡天气的 icebreaker T恤。
Start here
- Men's base layers — lightweight to expedition weight
- Women's base layers — same range, women's fit
- All icebreaker — base layers, tees, underwear and mid-layers
- All Smartwool — merino socks and Active Ultralite tees
- Visit us in store — try the weights on before you buy
Common questions
Do I need a base layer in Singapore?
For daily wear a lightweight merino tee is usually enough. A long-sleeve base layer earns its place for sun cover, for air-conditioned travel, and for any trip somewhere cold.
How many days can you wear a merino base layer?
Three to five days of normal wear in Singapore is common, and longer in cool, dry conditions. Airing it overnight helps.
Does merino shed microfibres?
All fabrics shed. Wool fibres are protein-based and biodegradable rather than plastic, and merino needs washing far less often.
How should I wash merino?
Cold or warm gentle cycle, mild detergent, no fabric softener, dry flat.