What Is Felt? How to make Wool Felt? And Felt Bags?

Wool felt is the oldest known textile. It was most likely discovered many times, in many different places, in many cultures, when early humans in the prehistory discovered that wool, shed from wild sheep, used to soften sleeping areas, formed a cohesive fabric when laying on it for a while – or that the wool on skins such as mammoths and bisons used for clothing became over time matted.

Clothing made of felt has an insulating, warming, quality; imagine how great this material must have been during the ice age to keep the head, body and feet protected from the harsh environment. But due to the biodegradable quality not much remained from the earliest time of felt making.

The traditional way of making felt is still carried out to this day by nomadic people in Central Asia, like the Mongols, Iranian shepherds, Caucausus, and Turkic of the Altai – for clothes, tents (yurt), rugs, and horse blankets.

Left: Saddle cover, 4th century BC, with mouflon (wild sheep) and swan, excavated in barrows, the burial mounds in the Altai Mountains, Southern Siberia.

Right: Felt cap, 4th century BC, Phanagoria Necropolis, Hermitage Museum, Russia.

The term "felt" was originally used only for matted natural animal wool fibres. Today "felt" refers to a technique and is used for a variety of different textiles, including felted woven wools, felted synthetics and industrial felts.

Usually, when manufacturers make a textile from wool, they first turn it into yarn and spin it into a woven textile, but this is not the case with making felt.

Felt is a non-woven textile material composed of loose fibres that is produced by matting, condensing, and pressing the fibres together. This is done using techniques that involve humidity, pressure, and heat.

The most common wool from animal fibre is the sheep. But there are differences in the quality per breed of sheep. The colour of the fleece is depending on their breed and genetic history, and there are many different colours like white, black, red, cream, grey, silver, and brown.

Corriedale, Blue Faced Leicester, Rambouillet and Merino are among the best-known wool sheep. Merino wool originated in China is considered the best quality. China has the world's biggest sheep flock estimated at about 140 million head and producing about 363,000 tonnes of wool.

Other animals that deliver wool fibres:
• Cashmere, angora goats (combed)
• Camels, llamas, alpacas, vicunas, guanacos (shearing)
• Angora rabbits (shearing)
• Musk oxen (shed each spring)
• Bisons (shed each spring)
• Beavers (killed, so not a good practice!)

Sheep grow wool to keep themselves warm during cold winters. This wool tends to tangle on fences or low-tree branches and is gradually shed off, meaning that sheep need to shed wool in their natural habitat to prevent overheating in the summer. Therefore, sheep must be sheared once a year.

Sheep are nowadays often sheared with advanced electric shears or shearing machines for reasons of efficiency and speed to prevent stress on the sheep. Some still do it with scissors or hand blades – in this case, some wool remains on the body, and is strangely enough, it is better for all year-round cold climates.

Shearing is an experienced skill of removing the fleece in one piece. It is obvious that sheep farmers do not want to damage or cause suffering to their livestock, and therefore they select well-trained shearers. On average, a sheep can produce 2-3 kgs of wool per year.

On the contrary, for many modern sheep, it is cruel not to shear them. Domestic sheep do not totally shed their winter coats. If one year’s wool is not removed its resulting in sheep that overheat in summer.

They get greatly decreased mobility and are in much greater danger from flystrike, all of which causes suffering and possible death. Shearing is nowhere near as cruel as the fur industry, for instance, which obviously requires the animals in question to die!

“Mulesing”, a practice mainly carried out in Australia, consists in the removal of strips of wool-bearing skin from around the breech (buttocks) – often including the tail – of a sheep, to prevent parasitic infection flystrike (myiasis). It is a crude attempt to create smoother skin that won’t collect moisture.

The exposed, bloody, and painful wounds often become infected and many sheep who have been mutilated still suffer slow, agonizing deaths from flystrike. But research has shown that it is possible to successfully manage non-mulesed sheep with little extra time or cost.

New Zealand, however, is one of the kindest environments for sheep to live in, with a pristine climate, clean water, fresh air, grass, and growers who look after their animals and land with utmost care.

In fact, New Zealand lawmakers have made history by officially passing a ban against sheep mulesing practices, following increased pressure from animal welfare groups and major clothing companies.

Real wool is easy to recycle and it biodegrades, releasing valuable nutrients into the soil. In fact some of the Dutch wool is now directly turned into soil fertilizers, an environmentally friendly peat.

Wool in essence is a circular material, and forms a part of the natural carbon cycle. However, wool is considered of negative value. It costs more to get it off the sheep, than it is paid for it by manufacturers. In such context, many sheep are only bred for meat, and their fleece is wasted.

An animal bred for just one of its outputs, such as meat, seems wasteful when its milk or wool could also be of value. Holistic thinking from start to end and the carbon cycle in wool is a promising direction for more sustainable practices.

Natural felt made from animals' fibres (fleece):
• 100% real wool from sheep, alpacas, vicunas, guanacos, goat (mouton) and camels. It is non-flammable and dirt repellent.
• Fur felt, like beaver or rabbit skin – not a preferred choice, as animals are killed for it.

Natural felt made from plant fibres:
• Cotton felt.
• Xotic felt – bamboo/rayon blend of made from 50% bamboo and 50% rayon fibres. Bamboo is considered a sustainable fibre as it is a fast-growing crop that does not need chemical fertilizers, but rayon does however need chemicals for its production. This felt is incredibly soft. It retains its shape with washing and does not shrink.

Synthetic felt (man-made fibres):
• Rayon felt – a semi synthetic fibre made from cellulose pulp (plant based mostly from trees).
• Polyester – a petroleum based, cured hard felt that has two different sides – one side is scratchy. Good for projects that need a rigid shape. Polyester is a versatile material popular in many types of garments, while acrylic is used for warm-weather clothing.
• Acrylic felt – a petroleum based. Acrylic felts wash very nicely and won't shrink but is highly flammable. The main difference between polyester and acrylic is that polyester is more breathable, and acrylic is a better insulator.
• Craft felt – mainly acrylic, polyester, rayon, or a rayon/viscose blend.
• Eco-fi – like craft felt but made of polyester fibre from 100% recycled (PET) plastic bottles. It is even more rigid than polyester felt.

Blended wool felt:
• Blended wool felt – made using the same process as for real wool felt, but made of Nylon, polyester, polypropylene, or cotton mixed with wool. Blended felt is pricier than craft felt, but it is less expensive than real wool felt.
• SAE (Society of Automotive Engineers industrial felt) – for high-pressure applications in industries, is a combination of raw wool fibres and polyester or cotton, rayon/viscose, synthetic, or plant fibres.

Left images – Felt examples:
1 – wool felt
2 – polyester felt
3 – craft felt
4 – SAE industrial felt

Long story short, animal or plant fibres are natural, easy to recycle, biodegradable, and fire resistant (creates scorched ashes). While in comparison, man-made synthetic fibres are petroleum-based, polluting (landfill pollution, microplastic pollution), non-biodegradable, and highly flammable (melting).

A – Wet felting (pressed felt)
Wet felting is the most traditional technique, and can be only done with real animal wool, wool blends, and fur fibres. Warm, soapy water is applied to layers of wool positioned at 90-degree angles to one another, causing them to hook together into a single piece of cloth. This process uses the inherent nature of animal hairs because the fibres have scales on them which are directional, and the hairs have kinks in them. It is the combination of these properties that reacts to the stimulation of friction and causes the phenomenon known as felting.
• Higher price point
• Smoother finish with better shape memory
• Uses sulphuric acid that needs to be neutralised with sodium chloride, but this process is improving.
• Heavier result than dry felting

B – Dry felting (needle punch felting)
With needle felting, any fibre works, man-made fibre and animal fibre; all artificial felts are needle-punched felts. A needle felted fabric is a non-woven fabric made from webs or batts of fibres in which special barbed felting needles on an industrial felting machine are used. The barbs catch the scales on the fibre and push them through the layers of web, tangling them and binding them together. This needling action interlocks the fibres and holds the structure together; it is popular for two- and three-dimensional felted work.
• Cost saving
• Less shape retention
• Clean product line without chemicals
• Less soft and flexible

C – Woven felt
With woven felted wool, there is thread and weaving involved. It is produced by applying heat, water, and pressure to pre-woven fabrics. The result is a matted fabric that can be much thinner than pressed felt.

Shown above:
A – Wet Felting / Pressed Felt: heavier, more dense smoother texture
B – Needle Punch Felting / Wool Roving: lighter, more open, slightly rougher, texture

To answer this question, we need to look at a microscopic level.

Polyester and nylon are normally produced as very smooth fibres that will slide past each other with ease; they cannot be matted into felt with the wet technique.

Real wool has areas of roughness, scales that allow adjacent fibres to naturally catch on one another.

A – Real Wool Felt
B – Polyester Felt

As mentioned earlier, not only are there quality differences by breed of sheep, but also the way a sheep is raised has consequences for the condition of the wool.

Heath sheep or stable sheep
A sheep grazing in the open field naturally picks up more dirt from its surroundings than an enclosed sheep. In fact, a sheep in the open fetches even less money for its fleece than an enclosed sheep for this reason, as it requires more cleaning.

Open or closed fleece
For example, the fleece of a Shetland sheep does not hold together as a unit and tends to have a lower fat content, as opposed to a fine wool breed such as Merino sheep, whose wool surface does not open and is characterized by a high fat content.

The sorting process is important as different sheep produce different quality of wool. The first step is to sort the wool into different categories. Various wool grades are combined to create a homogeneous mixture.

The quality of wool is also depending on the part of the sheep’s body it comes from. The best part grows on the flank side of a sheep, second best is the top and thirdly, legs and neck. Wool on the top and side of the sheep is often long and fine, but on the legs short and thick. Different kinds of wool are used to make different types of products. Longer wool is better suited for clothing, while the shorter wool is used for making rugs.

Criteria to judge the quality are:
• fineness (the finer, the softer)
• length (long fibres are the best quality)
• resilience/elasticity (preventing breaks)
• waviness or curliness (providing volume)
• colour (the whiter the more easily dyed)
• the presence of jar (unwanted thicker hair in the middle)

eKodoKi is based in the Netherlands and we are shocked to see that according to the Dutch Wool Federation, 80% of Dutch wool goes to China, due to cheap labour and easement of environmental and labour laws. The amount of travel miles for wool must be massive and this has an impact on the environment.

At one point in history, up until the 1950’s, most manufacturing of wool was done in The Netherlands, but nowadays, it is China that manufactures most wool and determines prices. China has bought most of Western Europe’s machinery for wool processing.

And shockingly, wool has been rated at negative cents per kilo. In general, The Netherlands rears sheep mainly for meat; wool is secondary. It costs more to get wool off the sheep than what is paid for. Most Dutch sheep wool disappears as fertilizer into the ground.

Some mills are cleaning the wool in an eight bowl system with eight squeeze rollers; the process is called scouring. This involves using hot water and detergents to remove soil, vegetable impurities, grease and contaminants from the fibres. Sheep wool has a lot of lanolin or grease that needs to be removed. Alpaca or llama have not any lanolin in their fibres and only need to be washed to remove the dirt.

Until the 1930s, wool was cleaned with human urine and water; nowadays it is done water and alkali – but scouring with an organic solvent is the preferred method. Important is that the dirty water is discharged a water recycling process, where the grease is separated, and cleaned water is being recycled in a loop.

Next the wool gets dried in huge dryers, fluffed up, and packed.

Since some felts use more than one types of fibre, the cleaned fibres must be mixed and blended first together. This is done either at the end of the scouring (washing) line, or with a replacing method that also removes the impurities in a process called willowing.

After that it tangles the fibres together and merges them into several layers resulting in a fluffy wool sheet where fibres lay in alternating directions, forming a net – called a batt. These batts are then rolled up and ready for the felting process.