What Is Octa Fleece?
The latest advancement in fleece technology was inspired by the octopus. Octa fleece is a yarn composed of polyester or recycled polyester that features a central hollow core from which an eight-sided fiber fins out, like little fuzzy tentacles. The octagonal fleece sections are connected by a mesh fleece backing, so the overall garment has a mesh exterior with a brushed fleece interior dotted with Octa fibers. It was actually invented in 2011, but didn’t start to appear in outdoor apparel from brands we all know till over a decade later.
The fabric's ingenuity is a construction where less is more. The old-school means of boosting heat retention would be to add more fabric; if you’re cold, another layer or a thicker garment should do the trick. Of course, for those looking to shed weight on ultralight adventures, or anyone involved in high output activities in which warmth is as important as breathability, heavy clothing isn't the best solution, and neither is constantly pulling layers on and off.
This became apparent to the Mountain Hardwear team when they first began testing Octa by wearing it around the office. “Users quickly fell in love with the fabric and we realized that because it actively adapts to your body’s changing temperature it keeps you comfortable across a wide range of activity levels,” said Senior Product Line Manager Brittany Beratlis. “Since it breathes with you as you move while also offloading heat as you warm up you really don’t need to layer up or shed down on a temperate day.”
Air pockets created by the thread structure effectively trap heat and help keep the wearer warm with less bulk. Since there are eight fins protruding off of each core, that leaves a lot more space in the design, requiring a lot less fabric. It plays out on the scale—Octa garments weigh in at 50% less than those made of yarns of a similar thickness.
With its abrasion-resistant mesh backing, Octa fleece is also durable. Yoji Kaneda, Danner’s director of lifestyle apparel and footwear, explained, “We wanted a mid-layer that could handle all-season use in the mountains—light and packable, yet warm and breathable for long hikes. After testing several fabrics, we found most lightweight fleeces too delicate for rugged environments.”
Photo courtesy The North Face
Octa in Action
You can’t quite outfit yourself in Octa from head to toe just yet, only because nobody's used it to make socks (though you can pick up Alpha Direct socks). But it has appeared in just about every other piece of kit from the ankle up. The ultralight backpacking brand Zpacks has even used it in accessories like gloves, hats, and gaiters, as well as midlayers.
A few brands have employed Octa as a baselayer. Beringia, the Bozeman-based apparel upstart with a Japanese design lab, put Octa on the inside of nylon shorts to create a cold-weather short “built to float” by sitting off the skin and providing warmth along with airflow. The North Face utilizes it in its Summit Series pants, which are remarkably comfortable on the skin along with having an impressive warmth-to-weight ratio. And the Paris running brand Satisfy worked with Teijin to work Octa into their FuzzFleece collection, which features delightfully soft short sleeve and long sleeve tees.
But don’t let the softness fool you. Those baselayers have serious performance chops. Kotaro Shiomi, Satisfy’s chief design officer, explained that a major appeal of the fabric was its quick-drying ability and weight compared to traditional fleece. Said Shiomi, “What makes FuzzFleece stand out is the sensation, warmth, lightness, and running comfort without distraction, allowing you to stay fully immersed in your run.”
Satisfy's FuzzFleece line is made up of standalone pieces, but where Octa really excels is as a midlayer or outer layer. Danner’s Ultralight Octa Pullover and Mountain Hardwear’s AirMesh layers are great examples of lightweight thermal efficiency that can work in a wide variety of temperature ranges. For increased weather protection, Octa can line a shell, as in Beringia’s Anorak, which has a nylon stretch exterior, or Norrona’s Octa Zip Hood with its woven nylon shell. In these cases the exterior shell offers protection against wind and light precipitation while the interior creates pockets of heat and moisture management in a lightweight package.
Ultimately, no fabric can be the solution for all situations, and Octa is no exception. It's a highly permeable fabric that fails to safely insulate in extremes. However, as Satisfy's Shiomi said, it shines as part of a system of dress and comfort, “built to sustain flow before, during, and after a run,” or any other outing in which you might sweat in cool conditions.
Frequently Asked Questions
How is Octa fleece different from other fleeces?
Like most fleeces, Octa fleece is composed of polyester or recycled polyester. However, the structure of Octa sets it apart. The hollow core from which eight fins protrude creates spaces, or “voids,” in the fabric. These octagonal sections are connected by a mesh backing, so that one side of the fabric features the smooth mesh, while the other features the loftier fleece components.
What are the main advantages of Octa fleece?
Because of the spaces within the fabric Octa fleece is lightweight, breathable, and able to trap heat. It is also quick-drying, both because fleece is a hydrophobic fiber that doesn’t tend to absorb water, and because the voids in the structure mean there is less fabric to soak up water in the first place. For the above reasons Octa fleece is an excellent choice for ultralight and high-output activities.
Are there situations when Octa fleece isn’t a great choice?
In high winds, heavy precipitation, or expeditions through rough terrain, Octa fleece would be a poor choice as an outer layer. The breathability allows wind and water to permeate, and though the mesh backing adds to the abrasion resistance of the fabric, it could still snag or tear on branches and rocks. In these situations it's best to wear Octa fleece as a midlayer with a protective shell over top.
Also, when you're in extreme cold and not moving around as much, Octa won't insulate well as there won't be enough body heat generated to trap in the fabric voids. A thicker midlayer or traditional fleece would be a better option.
How does Octa compare to Alpha Direct?
When it comes to moisture management, warmth-to-weight, and breathability, Octa fleece is comparable with Polartec's Alpha Direct fabric. Octa is more durable due to the abrasion resistant mesh backing. However, Alpha Direct is stretchier and more breathable, making it a better choice for warmer conditions where mobility is a priority.
For warm weather adventures, check out our guide to the lightest, airiest mesh shirts.
