Meet Arrowool™

Arrowool™ is the yarn inside every WORN sock. It uses Worn's patented yarn technology (US Patent No. 11,639,564): organic merino and a technical fiber, spun separately and twisted together instead of blended. The result is a sock that's ultra-soft, itch-free, stays dry through a full day and comes back into shape every wash.

We didn't invent merino. We patented a better way to build with it.

Twisted, not blended

Most merino blend yarns mix wool and synthetic fibers into one strand. That packs the fibers tight and lets one material bury the other. Arrowool does it differently. We spin the merino and the technical fiber as two separate yarns, twist them around each other at a controlled angle, and heat-set them so they hold.

Diagram comparing a blended yarn, where merino and technical fibers are mixed in one denser strand with fewer air pockets, with Arrowool, where separately spun organic merino and technical fiber yarns are twisted together with air pockets throughout. — *Most performance yarns blend fibers into one strand. Arrowool™ twists two separately spun yarns together, so both stay on the surface.*

That twist leaves air pockets in the yarn and keeps roughly a 50:50 split of merino and technical fiber on the surface, where it touches your skin. It took almost two years to get right. Apparently, we're particular about socks.

What it does

Stays dry. Manages moisture far better than cotton: dry through a full day and through multiple wears.
Refits itself. Cotton stretches out and stays that way. Arrowool comes back into shape every wash. We call that Wash-Fit™.
Soft, no itch. Ultra-soft and itch-free, not "wool that's supposed to be soft."
Resists odor. Naturally, with no chemical treatment.
Built to last. Made to outlast the cotton pairs you keep replacing, and backed by a 1-year warranty.

Tested, not just claimed

Our patent includes side-by-side tests of the same Arrowool™ socks we sell today against 100% merino and 100% cotton socks.

Test	WORN Arrowool™ socks	100% merino	100% cotton
Shape loss after 50 wash-and-dry cycles	Under 5%	About 15–20%	About 15–20%
Wear test	No holes, light pilling	No holes, heavy pilling	60% of socks had holes, snags or broken threads
Drying time (wet fabric sample)	About 15–18 seconds	About 40 seconds	About 72 seconds

That's roughly 4× faster drying than cotton and about twice as fast as 100% merino.

Results from the comparative testing documented in US Patent No. 11,639,564.

Arrowool vs. cotton vs. a typical merino blend

	Arrowool™	Typical merino blend	Cotton
How the yarn is made	Two yarns spun separately, then twisted (patented)	Fibers mixed into one strand	Single natural fiber
Moisture	Moves it, dry all day	Moves it	Holds it
Shape after washing	Comes back every wash (Wash-Fit™)	Can stretch out over time	Stretches out and stays
Odor	Resists it, no chemicals	Resists it	Holds it
Feel	Ultra-soft, itch-free	Varies	Soft at first

The patent

Patent: US Patent No. 11,639,564, "Twisted Yarns and Methods of Manufacture Thereof"
Granted: May 2, 2023
Inventor: Bryan Marville, WORN's founder
Held by: Wetsox, LLC DBA WORN

For the technical crowd: we spin merino (16–28 micron fibers) and the technical fiber into their own yarns first, each with an S-twist. Then we twist the two together the opposite way, in a Z, at roughly 15 to 55 degrees and 20 to 35 turns per inch, and heat-set the whole thing so it holds. The angle decides how much of each fiber ends up on the surface. Yes, we've thought about sock geometry more than anyone should.

Find your sock

If you need	Series
Socks for work boots and long shifts	Work
Hiking socks	Trail
Running and training socks	Athletic & Run
Ski and snowboard socks	Snow & Ski
Everyday socks that don't lose their shape	Everyday