Light is right. A lightweight, quick-drying fleece top and bottom are the core of a versatile cold weather clothing system.

This is the third post in a series on outdoor clothing systems.
An overview of the system can be found here.
The first post on base layers can be found here.

What the Fleece?
As with everything Outdoor, there are a bewildering array of choices in the world of polyester fleece clothing. If you take a look at the Polartec website you’ll find a half dozen different products that could be roughly lumped into the category of lightweight fleece. Some of these are actively wicking fabrics that can double as base layers in cold weather. Others are conventional polyester fleece in lighter, thinner lofts. Given all these choices, what does “lightweight” even mean when it comes to fleece?

The best way to think about this category is by thinking about what we want this second layer in our clothing system to do. We need a little bit of insulation to keep us warm, but not so much that we overheat when we’re active. Whatever we wear as this second layer should dry quickly. In fact, it would be great if our lightweight fleece insulation would actively wick moisture toward the outside of our clothing system just like our base layer does. Given this wishlist we need to be looking at the thinnest conventional fleece available or, better yet, some of the more technical fleece options in a similar thickness.

Good, Better, Best
“Good, Better, Best” is a marketing tactic designed to help people make choices between complex consumer options. For the retailer and manufacturer it is a helpful way to position products at various price points and tell a story about why someone would want to pay more for something that works better. For the shopper it can be a heuristic that helps you match your needs to your budget. Practically speaking it tends to drive people up the the price distribution in search of better value and may cause people to spend a little more money on a product than they had intended to.

That’s not what I’m talking about here.

I’m going to position the three main options in light weight fleece on a Good, Better, Best spectrum in an effort to explain the advantages of each material strictly from a performance standpoint, not in an effort to convince people to buy more expensive clothing. In the case of light weight fleece, Good, Better, Best doesn’t necessarily align with a specific price structure. You can find some very affordable options in the Best category if you don’t mind shopping on eBay or wearing coyote brown. And with that caveat, away we go…

Good
Good ol’ Polartec Classic 100 weight fleece is an outstanding light insulating layer for top and bottom. You’ll find this fleece called a variety of things including micro-fleece. It’s about an eighth of an inch thick and made of polyester fibers. Polyester is a hydrophobic (water hating) material–it doesn’t absorb water so it will dry quickly in use. Jump into the water wearing a Polartec fleece top and bottom and when you climb out you’ll feel the water drain rapidly out of the fleece. For years this material was my first choice for a light insulating layer, especially for paddlesports use where I might be going for a swim.

Polartec was the first, but there are scores of knock-off fabrics in similar thicknesses available from a wide range of conventional retailers. You can find fleece similar to this at Walmart or Old Navy or, for that matter, at the Goodwill. If you are on a budget and trying to put together a solid system of clothing conventional lightweight polyester fleece is an excellent choice.

Better
I would classify Power Stretch fleece as a better choice than conventional fleece for one reason: wicking. Power Stretch is a snug fitting polyester fleece with a smooth outer face fabric. The inner fleece layer of Power Stretch is made of polyester. The outer face fabric is 4-way stretch nylon. Since nylon is a hydrophyllic (water absorbing) material and polyester is hydrophobic, Power Stretch actively wicks moisture from the inside of the fabric to the outside. The nylon draws moisture away from the polyester and moves it toward the outside of your clothing system where it can evaporate into the environment.

The hard face fabric of Power Stretch makes it a bit more durable than conventional fleece and helps it to slide smoothly under other layers. The snug fit and 4-way stretch makes Power Stretch a good choice for highly active pursuits like running, especially if you are going to wear it alone without an outer shell. Power Stretch tights look like conventional running or cross country ski tights and many people wear them as a stand alone bottom for high intensity sports.

Power Stretch does have some downsides. Since it contains a high percentage of nylon it is slower to dry than conventional fleece. The snug fit can also be a hassle when trying to wear Power Stretch over a light weight base layer as it can cause the base layer to bunch up.

These shortcomings aside, Power Stretch is a step up from conventional lightweight fleece because of it’s active wicking properties. Power Stretch will do a better job of moving moisture from near your skin toward the outside of your clothing system than regular fleece will. Worn next-to-skin, Power Stretch can function like a heavy base layer. Worn over a base layer it works as light insulation. This is what we’re looking for from the second layer in our clothing system.

Best
Back in 1999 Patagonia introduced a series of new, high performance fleece products that they called Regulator. These fabrics were co-developed with Malden Mills (Polartec) and included a light weight wicking grid fleece and a heavier, high volume fleece that looked like a shaggy dog. The lightweight fleece was called R1 and the midweight fleece was called R2. These two fabrics were tested by the US Army research lab at Natick Soldier Systems and incorporated into the Protective Combat Uniform (PCU) which later became the Extended Cold Weather Clothing System (ECWCS), Gen III.

R1 is the heaviest weight of Polartec Power Grid fleece. Power Grid is woven in weights that range from light weight fleece down to midweight long underwear. It is a mechanically wicking fabric like Polartec Power Dry (discussed here). Power Grid is woven to have a polyester fleece grid on the inside and a smooth outside surface. The grid creates additional air space within the insulation to trap heat. It also helps the fabric to dry more quickly and compress better. Like Power Dry, Power Grid has a mechanical wicking action caused by a difference between the amount of surface area on the outside and the inside of the fabric. Moisture is drawn to the outer surface of the fabric and spread out over a larger surface area so that it can dry more quickly.

Power Grid is woven with bit of Lycra for stretch, but not enough to significantly slow drying times. If you run a Power Grid garment through the wash it will come out feeling dry on the inside and slightly damp on the outside. This is a big performance advantage over conventional fleece and Power Stretch fleece. Conventional fleece will come out of the washer feeling damp throughout. Power Stretch fleece will feel dry on the inside but very wet on the outer nylon face fabric. Power Grid holds less water that either of these other fabrics and does a better job of keeping that moisture farther away from your skin or base layer. Power Grid garments feel drier and dry faster than the other fleece options. This makes them the best option currently available for lightweight fleece layers.

The development and fielding of the PCU/ECWCS Gen III has created a surplus market in Power Grid tops and bottoms as well as some commercially available options. Many of these garments use Polartec products, while others use similar fabrics from other manufacturers. Military surplus grid fleece tops and bottoms are very affordable, and the knock-off grid fleece products seem to work as well.

What about Wool
We discussed merino wool in the base layer section of this series (here). Merino offers impressive odor control properties and excellent wicking. Wool fibers are somewhat absorbent, so wool layers will take longer to dry than polyester. This isn’t too much of a problem in a light weight base layer, but it becomes more problematic as fabrics get thicker.

Thicker versions of merino that would function as light insulation layers are heavier and slower to dry than their polyester counterparts. I have a very nice 220 gram Icebreaker top that is almost warm enough to use as a light insulation layer. That said, it is thinner (less warm) and nearly twice as heavy as any of the options listed above. Compared to the fleece options, merino is heavier, more expensive and slower to dry. The same goes for more traditional wool options like shirts, pants and sweaters–all are heavier and slower to dry than polyester.

Yes, wool is warm when wet, but so is polyester fleece, and both are warmer when dry. To my way of thinking, the only real reason to favor wool in a layering system is for odor control, and this is most critical at the base layer. For light insulation layers I prefer polyester.

Don’t get me wrong, I have a closet full of wool clothes including modern merino base layers and more traditional wool shirts and sweaters. I love the stuff for a whole range of specific applications. That’s not the point. This series of articles is focused on a simple and versatile framework for outdoor clothing. Wool comes up short on drying time and warmth for weight so it doesn’t make the cut in the light weight insulation category.

Fit and Features
Your lightweight fleece should fit comfortably over your base layer and under the other layers in this system. My preference is for garments that are close fitting but not tight. This kind of fit allows the layers to slide over one another without bunching. Snug fitting tops and bottoms like those commonly made from Power Stretch can bind on your base layer and twist it around your arms and legs–not very comfortable.

Features to look for in tops include a high collar that can be snugged up against your neck in cold conditions. This saves you the trouble of packing (and losing) a neck gaiter. A deep front zip allows you to open up the top for better ventilation during exertion, and a long hem will let you tuck the top into your pants to keep cold drafts to a minimum. Thumb holes in the sleeves are a nice option that makes it easier to slide additional insulation over the top of your light weight layer.

When looking for bottoms, decide if you want something that will be strictly an under layer, or something that you can get away with wearing in public. Men’s bottoms with a fly definitely fit into the “long johns” category, and while bottoms with a simple elastic waist band are frequently less expensive than those with a more finished waist, a more finished look makes it a little less kooky to wear your fleece pants to the bar. Patagonia currently makes an R1 pant that looks normal enough to wear around town but can still be used within a layering system.

Buy This, Not This
Given the quantity of surplus Polartec Power Grid tops and bottoms on the market, there is really no good reason to spend more than $30 or so for a top or bottom in Power Grid. The Level 2 tops and bottoms from the PCU are available in a huge range of sizes and can be found both used and new. If you don’t mind coyote crown (good bird watching color!) you can’t go wrong.

That said, the PCU isn’t cut in womens’ sizes. So ladies will get a better fit by seeking out commercial options in Power Grid or Power Stretch. My wife has found a couple of very nice Power Stretch tops at local thrift stores, so this option doesn’t need to break the bank.

Conventional polyester fleece is the most economical option. It can often be found at thrift stores in both tops and bottoms. There are plenty of polyester fleece pants sold as loungewear and these will function perfectly well in an economy clothing system. If your budget is tight, look in this direction.

Steer clear of heavier fleece garments and merino wool in this layer. The heavy fleece will be too warm for a versatile layering system, and merino performs better as a base layer than as a light weight insulation layer.

Sources:
Polartec Products Page

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