What is Alpha Direct Fabric?

What is Polartec Alpha Direct?


In the ever-evolving world of outdoor apparel, advancements in fabric technology continually push the boundaries of performance and comfort. One such innovation that has captivated outdoor enthusiasts is Polartec Alpha Direct fabric

Alpha Direct was originally created for the military to keep troops warm without overheating while marching with heavy gear in cold weather. It is considered an "active insulation" that provides outstanding performance when the wearer is exerting themselves. 

From its inception to its current, rather unexpected applications let's delve into the intricacies of Polartec Alpha Direct.

What is the Difference between Alpha and Alpha Direct?

Polartec Alpha

In 2012, Polartec partnered with U.S. Special Forces to create an insulation that would be highly breathable as well as warm fast-drying, and ultralight. It was intended to be sandwiched between a breathable outer shell, and a lining.

However, all good things developed for the military trickle down to the gear junkies who want to use the technology for their own use, especially those who appreciate highly functional garments. Alpha was being used by many to make stand-alone garments. But, it lacked durability without a lining.

Alpha Direct

About 5 years after Polartec Alpha was developed, Polartec introduced Alpha Direct. 

The primary goal was to develop a fabric that could provide insulation directly to the wearer, eliminating the need for additional lining fabrics. Hence the name Alpha "Direct".  This streamlined approach not only reduced weight but also enhanced breathability, allowing moisture vapor to escape more efficiently. Through extensive research and testing, Polartec succeeded in creating Alpha Direct, a breakthrough in insulation technology.

While its main market was still insulation, brands such as Rab starting marketing a stand-alone jacket that showcased the ultralite features of Alpha Direct. Some of their designs, suchas the Rab Alpha Freak utilized both Alpha Direct and Polartec Power Grid. (A personal favorite mix, because the Power Grid adds the stretch that Alpha Direct lacks, for more fitted designs).

Enter the MYOG (Make Your Own Gear) and sewing world! While the fabric was not easy to source, several cottage brands as well as DIY'ers started making hoodies, hats, jackets and camp pants from Alpha Direct. And a Star was Born!

Picture shown is Hunter with his mom Jackie. Both work at Discovery Fabrics. Hunter sewed both his own hoodie, as well as the jacket Jackie is wearing. Note that the jacket combines both Alpha Direct and Polartec Power Grid, for added ease of movement.  

Properties and Performance of Alpha Direct Fabric.

At the heart of Polartec Alpha Direct lies its unique construction. Unlike traditional insulating materials, Alpha Direct features a lofted knit structure that traps warmth while maintaining exceptional breathability. 

This innovative design allows air to circulate freely, regulating body temperature and preventing overheating during intense activities.

Despite its lightweight composition, Alpha Direct boasts impressive warmth-to-weight ratio, making it ideal for a wide range of outdoor pursuits. Whether hiking, skiing, climbing, or simply walking the dog, garments crafted from Alpha Direct offer unparalleled comfort and versatility.

Moreover, Alpha Direct fabric dries quickly, ensuring that users stay warm and dry even in damp conditions. This moisture management capability is especially valuable for high-intensity activities where sweat can accumulate rapidly.

The open knit of Alpha Direct does not repel the wind in any way! Often it is worn alone but for any wind or rain protection, it must be partnered with a technical shell such as Polartec Neoshell

How much does Alpha Direct Fabric Weigh?

 As this blog is being written, there are literally dozens of styles of both Alpha and Alpha Direct Polartec produces. We will never be able to keep it current as they sell out often as quickly as they arrive. For your convenience, we list all the weights and specs of fabrics on our website, for styles that are in stock. So if you need to know GSM (grams per square meter) you can check the pages Polartec Alpha and Polartec Alpha Direct.

Some of the Alpha Styles we have seen or have in stock:

Style 4404 125 GSM

Style 4408  100 GSM

Style 4409   61 GSM

Style 9717 (quilted style with water repellent face)  139 GSM

The quilted style was a military run, we have never seen it anywhere else. Even though it is not Alpha Direct, we've made some pretty cool vests with it that are holding up well. 

The most common weights of Alpha Direct are 

  • Style 4028 60 GSM
  • Style 4004 90 GSM
  • Style 4008 120 GSM
  • Style 4024 190 GSM
  • Style 4048 with Wool 150 GSM

NOTE: Alpha  and Alpha Direct styles are an approximation that Polartec provides, and are not 100% accurate for every roll. We do find slight variances within these styles. 

Some of the cottage-industry manufacturers advertise their finished Alpha Direct jackets and hoodies at about 5-6 ounces, or 140-170 grams. But I'm guessing this is a 90 GSM style. I personally have made a 60 GSM hoodie in a Men's medium size that weights about 110 GSM. 

Bottom line: it's subjective, as it would depend on the pattern used, the size of the garment, and the style of Alpha Direct chosen. 

We believe there is a "sweet spot" of warmth to weight ratio, with the 60 GSM being our top choice. It is ridiculously light, and I love it for an extra layer when I'm packing for a trip because it compresses so well, but is just what is needed on a cool day.  I also find that making a double layer (or reversible) hoodie from 60 is almost a magical formula. It gives even more warmth than one layer of 120 GSM, while weighing roughly the same. 

Which Side is the right side?

To be honest, it can be difficult to tell. 

On some styles, particularly the lightest ones, both sides seem pretty similar.  On other heavier styles of Alpha Direct there is a side that just looks nicer.  

First you need to understand that Alpha Direct was created to be a lining for a breathable shell such as Neoshell or Power Shield Pro. Imagine a typical printed lining for a suit…let’s say it has a design with stripes on just one side. When looking at the fabric, the striped side would be the “right” side…but when sewn into the jacket the stripes would face the body. 

So, when looking at Alpha the nicest looking side (often the side with most fluffiness) is typically the right side.  If you are lining a coat, that nicer side would face the body  

But, if you are making a stand alone garment such as a hat, hoodie or ultralight jacket you might want the nicer side to face out…just because it looks better. 

It does not appear to make much difference in warmth or function so do what pleases you the most!  

When you order from Discovery Fabrics we typically ship with the Alpha fabric folded with the right side facing in. 

Can you Dye Alpha Direct?

Yes, you can. Alpha and Alpha Direct are made with Polyester. So, you just need to use a dye for synthetic fabrics. It is recommended to use a fixative to keep the dye from fading. We personally have just tried dyeing samples, but members of our Facebook discussion group have shown examples of garments they have dyed quite successfully.  There is a Youtube video where we discuss dyeing Alpha. 

What can I make using Polartec Alpha Direct?


A hoodie is a good idea for beginner sewist.  There are many good patterns. We recommend the Alpha Raglan Hoodie by Learn MYOG. We also like the Marie Claude by Jalie Patterns. There are lots more, we recommend asking in our Facebook Group, which just happens to be the best one ever. But I digress...


Sewing Alpha is not difficult, and despite it looking thin it is easy to add a zipper. For the lightest weights, make sure you use a coil zipper no larger (width) than 4.5mm. Lucky for you, we have those! 

Several well know outerwear brands have sold zipper Alpha Direct jackets for upwards of $200.  The effort to make your own can really pay off, especially if you don't fit into standard sizes, or have a long torso or arms. 


Pants are mainly for lounging, or wearing in a sleeping bag when camping. There can be fairly see-through and I wouldn't go shopping in them. You might...and I won't judge.  But still.  

Once again, Learn MYOG has a pretty cool pattern for Camp Pants made with Alpha Direct. We did a video showing this pattern on our Youtube channel. We do a lot of videos, so hope you will subscribe! 


Once of my favorite hats to wear under a cycling helmet is made with Alpha Direct.

Discovery Fabrics developed a pattern for a beanie hat that is intended to use with stretch fabrics such as Polartec Power Stretch or Polartec Power Grid.  I sized up 2 sizes and added 1" of length to the hem to accomodate for the lack of stretch in Alpha Direct, and was pretty happy with the fit.  


I don't see a lot of companies making Alpha Direct vests but you are missing out on an amazing way to keep your core warm without overheating by wearing a vest.  I like simple designs, and have used Fold Over Elastic (also know as FOE) instead of hemming the bottom and cuffs, for a very easy make! 


Ask for Advice!


Where can you get help choosing a fabric?  

We love to help, which is why we have a Facebook Group. We have made many garments with this fabulous fabric. If you ask in our group, be specific about where you are going (climate), what you will be using it for.  We will try to make suggestions that will fit your need. We are always happy to chat in the group, where others can learn from the questions you ask!  Our Facebook group is Sew Inspired by Discovery Fabrics. Please join us! 

Boys wearing Polartec Alpha Direct Hoodies