RAL Merino Coolmax L/S Tee

2025/3/24 木村まさし

Tomo-yang, Mechanic, Heather, 168cm tall, Size M

I’ve been searching for the perfect weight merino wool fabric that works just as well as an inner layer or worn on its own, and I’m happy to say we were able to make this T-shirt using what I believe is the best fabric currently available.

If I really wanted to find the "ideal" fabric, the only way would be to have it custom-made, but as is the fate of mass-produced items, that would require a massive lot size—something unrealistic for us right now. Because of that, I’ve looked at just about every merino wool cut-and-sew fabric currently circulating in Japan, and I made the best choice possible.

Materials / Fabric Features

It’s a 50% merino wool and 50% polyester blend, and I was quite meticulous about choosing this specific ratio.

Monjya, SimWorker, Green, 182cm tall, Size L

As you know, merino wool comes from merino sheep and is one of the highest-quality materials among all wools. Merino wool is excellent for its moisture absorption, heat retention, and antibacterial/odor-resistant properties.

High moisture absorption draws moisture away from the skin and releases it into the air, keeping you feeling cool.
The fibers are fine and supple, providing a soft and gentle feel.
High heat retention protects you from cold outside air.
The surface of the fibers repels water, making it difficult to feel chilled by sweat.
Its properties prevent bacteria from settling, which helps keep odors at bay.
It has a strong capacity to absorb and neutralize foul odors.
It resists stains and dirt, allowing you to wear it for days without needing to wash it.
Excellent insulation keeps you cool in summer and warm in winter.

While you can expect all these benefits, it inherently struggles with durability. A 100% merino wool T-shirt is fantastic, but the drawback is that it tears easily.

That’s where a polyester blend comes in—it provides the strength and shape retention necessary for tough, everyday use. Plus, blending in polyester adds quick-drying capabilities.

Uno-chang, Logistics, Olive, 176.5cm tall, Size L

Furthermore, we used COOLMAX® for the polyester. COOLMAX® is a 100% polyester moisture-wicking fiber developed by DuPont in 1986. This fiber absorbs sweat and wicks it away quickly, keeping you cool and dry.

COOLMAX® uses capillary action to pull moisture up and disperse it. It’s not that the material itself is cool to the touch, but by instantly absorbing and evaporating sweat from your body, it keeps you feeling cool and comfortable.

Textile / Textile Features

The fabric is designed with polyester on the surface and merino wool on the inside, which makes for an incredibly comfortable feel against the skin. It feels great.

Details / Product Details

The fabric is dense enough that the silhouette looks great even when worn on its own.

We've completely overhauled the material from the merino T-shirt we sold last year, and it’s even better now.

And it’s not just the fabric we updated.

We also refined the details.

First, the cuffs. We redesigned them with a bit more tension so that they stay in place better when you roll your sleeves up.

We also tightened the neckline slightly to prevent it from stretching out.

Also, our biggest regret from the last version was the hem length! We pushed it a bit too far and it was a little short, so we added 3cm to correct it. I think this really hit the sweet spot.