What Is Fleece?

How is fleece made?

Fleece is made by knitting a fabric and then finishing its surface so the fibres stand up as a soft, furry pile. Polartec describes its fleece as “a knitted material” turned into pile by surface-finishing techniques, and its company page lists shearing among its production steps.

1. Knitting. Yarn, in synthetic fleece a fibre such as polyester, is knitted into a base fabric. A 2018 study of textile shedding described microfleece as knitted terrycloth that is mechanically napped and/or cut.
2. Napping. The same study defines napping as feeding fabric over revolving cylinders to create a soft, velvety appearance.
3. Finishing. Polartec lists shearing alongside knitting and dyeing in its production steps.

Where synthetic fleece came from

Polartec, which traces its origins to the textile firm Malden Mills, dates “the synthetic fleece” to 1981 in its own company timeline. The same timeline records bright Polarfleece prints on European ski slopes in 1986 and, in 1993, the first fleece made with recycled content, launched in “Soda-Bottle Green”, the colour of the discarded bottles. These dates are the company’s own account.

The older meaning: a sheep’s fleece

Fleece also names the woolly coat of a sheep. Both US and EU labelling law use it in this sense: US rules define wool as fibre “from the fleece of the sheep or lamb” or hair of the Angora or cashmere goat, and the EU defines wool as fibre from sheep’s or lambs’ fleeces.

What are the properties of fleece?

Polyester fleece absorbs very little moisture, resists shrinking and creasing, and builds up static, but it may pill, attracts lint and body oils, and melts if it gets too hot. The table gives properties of the polyester fibre.

How is fleece graded or measured?

No US or EU rule grades fleece: the law regulates how its fibre content is labelled, while weight and warmth are described by each maker. Polartec, for example, sells its fleece in Micro, 100, 200 and 300 series, from “ultra-lightweight” Micro for mild conditions or layering to “heavyweight” 300 for extreme cold.

• Series names are not grams. Polartec’s fleece page describes these series in words and gives no gram weights.
• Shedding has a test method. Polartec reports its shedding results as measured under the AATCC 212-2021 test method.

How does fleece appear on a clothing label?

On a clothing label, fleece fabric appears under its fibre names, such as “polyester”, with percentages by weight, because neither US nor EU law recognises “fleece” as a fibre name. The word “fleece” on a label is a description of the fabric.

Under US rules

• A textile label must give the generic names and percentages by weight of the fibres, the name or registered identification number (RN) of the manufacturer or marketer, and the country where the product was processed or made.
• Polyester is a generic name with its own chemical definition: at least 85 per cent by weight of a particular type of ester.
• Fibres under 5 per cent of total weight are normally grouped as “other fiber”. A fibre with a clear functional purpose may still be named, such as 4 per cent spandex added for stretch.
• Stated percentages may vary by up to 3 per cent of total fibre weight; this tolerance does not apply to a product sold as made wholly of one fibre.

Under EU rules

• Only the fibre names in Annex I of Regulation (EU) No 1007/2011 may be used, and “polyester” is one of them. “Fleece” is not.
• All fibres must be listed with their percentage by weight, in descending order. “100 %”, “pure” or “all” may only be used for a product made of a single fibre.
• “Fleece wool” and “virgin wool” are protected names for wool that has not previously been incorporated in a finished product, has not been spun or felted beyond what manufacture requires, and has not been damaged by treatment or use.

How do you tell good fleece from poor fleece?

You judge fleece by reading the full fibre line and then checking the pile, the knit underneath it, and any signs of heat or wear.

1. Read the fibre line. Look for generic fibre names with percentages. A label that says only “fleece” or a brand name has not told you what the fabric is made of.
2. Rub the surface and check for pills. Polyester may pill and attract lint. Heavy balling on a barely worn piece is a warning sign.
3. Look at the knit under the pile. In the 2018 shedding study, loose textile constructions shed more fibres, and the degree of shedding was related to how tightly the yarn was knitted. The authors concluded that high-twist yarns are preferable for reducing shedding.
4. Smell the collar and cuffs. Polyester absorbs body oils and perspiration odour, so a second-hand fleece that still smells after washing may keep doing so.
5. Look for heat damage. Hardened or melted patches mean the fleece met an iron or other heat too hot for the fibre.
6. Know the burn signature. Polyester is difficult to ignite, burns with a shiny, yellow-orange, sooty flame and a sweet smell, and goes out when the flame is removed. If you try this, use a loose thread from inside a seam allowance, held over a sink, never the garment itself.

Red flags: a fleece sold as wool whose label lists polyester first; “100 %” on a blend sold in the EU; pills and lint on a piece sold as new.

How do you care for fleece?

Wash fleece in cold water with a mild detergent, skip fabric softener, and tumble-dry it on low or hang it to dry, as Polartec advises; always follow the garment’s own care label first.

• Stains: spot-treat oil and grease before laundering, since polyester holds on to oils.
• Heat: keep it low. Polyester melts if too hot; if you must press it, use a low iron setting with steam.
• Detergent: in the 2018 study, washing with detergent significantly increased fibre release for three of the four fabrics tested, so more detergent is not better.

Is fleece sustainable?

Polyester fleece has one well-documented problem: in a 2018 peer-reviewed study, polyester fleece shed the most microfibres of all the textiles tested.

• Shedding. The researchers, who knitted most of their test fabrics at the Swedish School of Textiles, tested acrylic, nylon and polyester. All the textiles shed, but polyester fleece shed the most: an average of 7,360 fibres per square metre per litre in one wash, against 87 for the other polyester fabrics.
• Per garment. Scaling up their per-wash counts, the authors estimated that one fleece garment could release about 110,000 fibres.
• Wear. Worn fabrics shed more than new ones in the same study.
• What could help. The authors suggested better textile construction, prewashing and vacuum exhaustion at production sites, and more efficient filters in household washing machines.
• Recycled fleece. Polartec says it launched the first fleece with recycled content in 1993 and that most of its fleece is made from post-consumer recycled polyester from plastic bottles. That is the company’s own claim.
• Low-shed claims. Polartec says its “Shed Less” fleece reduces fibre fragment shedding by up to 85 per cent on average in home laundering, measured under AATCC 212-2021 against a baseline fabric. This too is the maker’s claim.

For the wider debate on fibre choice, see sustainable fashion.