Fleece is a durable and versatile man-made fabric – an important part of the contemporary clothing industry.
A fleece top can be used during cool days as an outer layer because it’s warm and comfortable but breathable at the same time. Fleece jackets are often windproof and water-resistant or water-repellent, which is not typical for most regular fleece tops. On cold days, a fleece can be used as a mid layer under a waterproof breathable insulation jacket, for example. Mid layers are used to trap still air next to the skin and provide insulation and fleeces do exactly that. They provide warmth and thermal insulation and keep you comfortable in cold and wet conditions given that you have a good rain jacket to keep you dry from the outside.
Regardless of its use, fleece has huge benefits over other fabrics and the rest of this text is intended for showing some of them. But let’s start from the beginning.
All about fleece
Fleece (sometimes called pile) was first used in clothing by the Norwegian company Helly Hansen. In 1961, Helly Hansen together with Norwegian Fiber Pile Inc. created the first fleece called Fiberpile. The Swedish lumberjacks were among the first people who found out that it offered great thermal insulation in wet and cold conditions.
In the United States, Malden Mills (nowadays called Polartec) made a smoother version called Polar fleece in 1979. Actually, Polartec accepts 1981 as the birth year of the polar synthetic fleece made by engineering polyester fibers into a new knit construction. Then Patagonia developed a pile called Synchilla (comes from synthetic chinchilla) with Malden Mills. It was softer, double-faced fabric that did not pill. This, with the developments of Pontetorto’s Tecnopile (or Technopile) in Italy – they began producing pile fleece fabrics in 1985 – represented the emergence of the polyester fleece technology prevalent today.
Fleece fabric is a synthetic fabric often made of a plastic such as polyester, polyolefin or polypropylene. Anyway, in most cases, it is manufactured from polyester. Some of the most important properties (for manufacturing hiking clothing) of polyester fibers include the following:
- Polyester fibers are hydrophobic making them water-repellent, moisture-wicking, and quick-drying.
- They are very durable and resistant to stretching.
- Polyester fibers do not shrink.
- Wrinkle and abrasion-resistance.
- Resistant to chemicals and easy to care for.
- These fibers are lightweight and cheap to produce.
In addition, the polyester fabrics can be given hydrophilic coating making them moisture-wicking – crucial for easy transportation of moisture from the skin to the outer surface and from there to the environment.
Because of all these properties, polyester has been used in various sportswear applications since the 70s. Generally, synthetic fibers have been widely preferred for activewear due to the multitude of performance enhancements they offer compared to natural fibers. Textile fibers contribute toward moisture control, thermal regula?tion and breathability, cooling effects, softness, stretch, and UV protection.
Fleece fabric is manufactured from polyester, which is spun into yarn. This yarn is then knitted into a fabric with tons of tiny loops. The loops are then sheared, or napped causing the fabric to puff up and become thicker forming a soft-handle pile. Finally, the pile is shaved down to an even length. The resulting fabric is lightweight, breathable, durable, quick-drying, and easy to care for (typical properties of the polyester). Additionally, fleece remains warm when wet (typical for sheep’s wool, in general) and does not absorb moisture. Moreover, it is so good at insulation that it has an insulation capacity similar to that of wool, however, at roughly half the weight. The fabric may also be treated with a durable water repellent (DWR) thus making the fleece rainproof. However, you can’t rely on it to replace a regular waterproof rain jacket in a heavy and/or continuous rain.
Sustainable alternatives include fleece garments made from recycled polyester and PET plastic bottles. For example, Unifi Manufacturing Inc. produces REPREVE recycled polyester fiber from plastic bottles. Patagonia was the first outdoor clothing manufacturer to use recycled fleece, back in 1993.
Fabric weight or grade
Pile is manufactured in a variety of weights and finishes, offering different amounts of loft and insulation and numerous layering possibilities. For instance, Polartec grades its classic Polartec fleece fabrics as 100, 200, and 300 weight. The higher the number, the heavier and warmer the pile, as Polartec 100 is equivalent to 9.5 oz per linear yard, Polartec 200 is equivalent to 12.5 oz per linear yard, and Polartec 300 is equivalent to 16 oz per linear yard. Other manufacturers label their fleece tops “lightweight”, “midweight”, “heavyweight” or by the fabric weight in grams per square meter (usually 100g/m2, 200g/m2, 300g/m2).
- Warm – fleece is warm because of its structure. Air is trapped between the fibers in the pile, creating excellent thermal insulation even in wet and cold conditions.
- Remains warm even when wet – worn over a wicking inner layer and under a waterproof breathable jacket, it can keep you warm in just about any weather while you are on the move and is particularly effective in wet, cold weather. Fleece moves moisture quickly and warms you fast enough even in very cold conditions.
- Highly breathable – and what’s more – fleece can be inherently water-repellent (when it’s made of a hydrophobic material such as polyester) so it continues to be breathable even when wet making it an ideal material for wet and cold conditions.
- Moisture-wicking and quick-drying – it’s hydrophobic meaning that it repels and does not retain/absorb water. Additionally, fleece fabric allows hydrophilic treatment done to modify its surface and to increase the fleece’s surface energy. This is what enhances the surface’s wettability and adhesion meaning that the fabric can distribute moisture evenly on its surface for faster and more efficient transportation.
- Durable – fleece is a very sturdy fiber because it’s made of polyester, which is made from a recycled PET. And we all have seen how durable plastic bottles are.
- Cheap – one of the most important competitive advantages of polyester in comparison with the natural fibers is its low cost. This is one of the reasons for the ever-growing use of polyester and why nowadays it is the most used fabric in the clothing industry. Since pile is made of polyester, it’s also much cheaper than wool, for example. Additionally, it’s environment-friendly – there aren’t many other widely-used materials made out of recycled PET bottles.
- Light – fleece is a lightweight material, which makes it a good alternative to wool for outdoor activities such as hiking, backpacking or mountaineering.
- Provides soft, non-itch feel – fleece was meant to imitate wool but without some of wool’s cons such as its difficulty in washing or itchy feeling. Thus wearing fleece on the trail shouldn’t cause any skin problems.
- Easy to work with – despite the fact that it’s thick, fleece is actually easier to use than many other fabrics.
- Doesn’t shrink – quality pile made from 100% polyester is not supposed to shrink unless you wash and/or dry it at a very high temperature.
- Not windproof – it has poor wind resistance – you can easily blow through it meaning that you need an additional wind-resistant layer over it even in a cool breeze. There is windproof fleece clothing, but it’s heavier, bulkier, and less breathable than ordinary fleece.
- Doesn’t compress well – hiking clothing made of/with fleece takes up more room in the pack.
- Repels cleaning products (because of its water-repellency) which can lead to a buildup of bacteria and odors.
- Pollutes the environment – microplastics from fabrics such as fleece are released into wastewater systems during fabric finishing and normal laundering processes. They are dispersed over long distances by wind and ocean currents, where they accumulate in the environment and work their way into the food chain.
Fleece as part of a hiking clothing layering
A fleece top can serve two purposes in a layered clothing system:
- An outer layer for cool conditions – fleece jacket, fleece hoodie, and others; and
- A mid layer, worn between a base layer top and an insulation jacket, to increase warmth and buffer moisture in cold-and-wet conditions. This is the primary role of a fleece in a layered clothing system.
Polyester fleece is used as an outer layer in crisp temperatures. Fleece outerwears are usually windproof and water-repellent and though these characteristics make them warmer and suitable for an outer layer in cool weather, they reduce breathability, slow dry times, and are not as fast at wicking moisture in comparison to standard fleece. They are very warm but not very versatile since you can’t separate the layers. Hoods can be useful in cold weather but they aren’t typical for most fleece tops.
From left to right: Fleece, Fleece Hoodie, Fleece Jacket
To make pile windproof you have to add a windproof layer – usually thin nylon, polyester shell, lining or a membrane. Any of these makes fleece garments bulkier and heavier than standard pile. It’s far warmer than regular fleece and will also keep out showers, though not heavy rain. “Heavyweight” fleece is useful for such applications, though you may feel it too warm while hiking. Anyway, fleece outerwears are soft and comfortable, and many people wear them in camp or as everyday use. The lighter types can also be used as a convenient outer layer, especially during summer hiking trips.
In wet and cold conditions, fleece is a perfect mid layer, worn between a base layer top and an insulation jacket (or light rain shell) meant to protect you from the elements. In such a case, pile is used primarily because of its thermal insulation ability.
A fleece intended to be used as a mid layer should be simple. Avoid features that add weight, absorb water, reduce breathability, slow dry times, and add cost. Stick to “lightweight” and “midweight” fleece tops for this application. Generally, which one you should choose depends mainly on your preferences.
The lightweight fleece (sometimes called also microfleece) is lighter, thinner, more breathable, functional and versatile than the other two types of fleece tops. This is actually the original mid layer used between a moisture-wicking base layer top and a waterproof breathable insulation jacket. During cold weather hiking, you can wear two of these instead of a heavier fleece. In milder weather, one will be enough to provide you enough warmth. This type of fleece is meant to be light, so don’t expect to find additional features like a hood or multiple pockets. Most manufacturers of fleece tops have thin microfleece garments in their range, and there are plenty of choices.
The midweight fleece is used as a mid layer for cold weather hiking. It’s also pretty convenient for camp use, especially in wet and cold conditions. Midweight tops offer better thermal insulation than lightweight fleeces and can be used as an everyday outer layer in cool weather. However, this type of pile offers less flexibility. There are many midweight tops on the market so you have plenty of choices.
Fleece tops should be fairly close-fitting to trap warm air efficiently. They are prone to the bellows effect* so the hem should be elasticized, have an inner elastic cord and cord locks, or be designed to tuck into your pants. Elasticated cuffs offer a customized fit and protection from the cold. A high collar with chin guard helps keep your neck warm and stops warm air from escaping. Full or half zip helps for better temperature regulation as you can easily let in fresh air to ventilate your body if needed or even take off the garment is it becomes too hot.
Fleece jacket design
Fleece jackets usually have a stand-up collar with full-zipped entry and set in, or raglan sleeves. A basic model often includes two hand pockets; however, design details on more expensive fleece jackets include chest or sleeve pockets and offset seams for comfort. Folded elastic binding is often used on the cuff, hem, and hood edges. Seams are constructed using stretch stitches such as four-thread overlock (mock safety stitch) and top and bottom cover seam, or flatlock where a low profile is required. An example of a typical fleece jacket design is shown in the figure below.
The fabric is lightweight and densely woven for better wind resistance. The fleece outerwear is often treated with a DWR for better water resistance. Detailing is minimal, usually comprising side-entry pockets and a hood. At lower price points the cuffs, hem, and hood are bound with folded elastic; however, increasingly complex adjustment systems allowing one-handed operation are introduced as garments become more expensive. Application of discontinuous baffles may provide comparatively more flexibility. Abrasion-reinforcement of certain parts supports thermoregulation in specific body areas such as shoulders, chest, and forearms.
Typical Jacket Design
Pile’s warmth (and low price) has increased its popularity for indoor use – it
has become the base fabric for a variety of blankets. It’s also used for pants (especially as a lining material), sweatshirts, hoodies, vests, headgear, mittens, scarves, pajamas, baby diapers, and in many other applications.
Fleece is a synthetic material manufactured primarily from polyester, though some fleeces are made from other man-made fabrics and even merino wool. For many years now pile is the standard fabric for warm garments. This material offers very good thermal insulation even when wet, moves moisture quickly, and is light, sturdy, almost nonabsorbent, quick-drying, and relatively cheap. These properties make fleece fabric ideal material for the outdoor clothing industry.
There are basically three types of fleece tops depending on the thickness of the fabric, as manufacturers label their fleeces “lightweight”, “midweight”, “heavyweight” or by the fabric weight in grams per square meter. For example, Polartec, one of the pioneers in pile manufacturing, label them Polartec 100, 200, and 300 (from lightest and thinnest to heaviest and thickest respectively).
Fleece can be used either as a mid layer between a base layer top and an insulation jacket or as an outer layer. Lightweight and midweight garments are more appropriate as a second layer. Simple, streamlined models are best for such applications because they’re lighter, more functional and versatile. Heavyweight fleeces are used mainly as outer layers. As such, fleece jackets are usually windproof and are often treated with a DWR for additional water resistance. There’s a wide range of fleece jackets on the market. The higher the price, the more additional features they usually have, which doesn’t always correspond to increased functionality.
* Bellows effect – Body movements result in a bellows effect that pumps the microenvironment air around and through clothing layers. Increased external air movement also increases air exchange, even if clothing is constructed from relatively air-impermeable fabric. This exchange can decrease clothing thermal insulation and water vapor resistance, which influences the heat balance of the wearer.
** In J. McLoughlin, & T. Sabir (Eds.), High-Performance Apparel: Materials, Development, and Applications, 2018, Elsevier Ltd., p.436