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insulating feltHow felt is made

Most fabrics are woven, meaning they are constructed on a loom and have interlocking warp (the thread or fiber that is strung lengthwise on the loom) and weft (the thread that cuts across the warp fiber and interlocks with it) fibers that create a flat piece of fabric. Felt is a dense, non-woven fabric and without any warp or weft. Instead, felted fabric is made from matted and compressed fibers or fur with no apparent system of threads. Felt is produced as these fibers and/or fur are pressed together using heat, moisture, and pressure. Felt is generally composed of wool that is mixed with a synthetic in order to create sturdy, insulating felt for craft or industrial use. However, some felt is made wholly from synthetic fibers.

Felt may vary in width, length, color, or thickness depending on its intended application. This matted material is particularly useful for padding and lining as it is dense and can be very thick. Furthermore, since the fabric is not woven the edges may be cut without fear of threads becoming loose and the fiber unraveling. Felted fibers generally take dye well and craft felt is available in a multitude of colors while industrial-grade felt is generally left in its natural state. In fact, felt is used in a wide variety of applications both within the residential and industrial contexts. Felt is used in air fresheners, children’s bulletin boards, craft kits, holiday costumes and decorations, stamp pads, within appliances, gaskets, as a clothing stiffener or liner, and it can be used as a cushion, to provide pads for polishing apparatus, or as a sealant in industrial machinery.

Felt may be the oldest fabric known to man, and there are many references to felt in ancient writings. Since felt is not woven and does not require a loom for its production, ancient man made it rather easily. Some of the earliest felt remains were found in the frozen tombs of nomadic horsemen in the Siberian Tlai mountains and date to around 700 B.C. These tribes made clothing, saddles, and tents from felt because it was strong and resistant to wet and snowy weather. Legend has it that during the Middle Ages St. Clement, who was to become the fourth bishop of Rome, was a wandering monk who happened upon the process of making felt by accident. It is said he stuffed his sandals with tow (short flax or linen fibers) in order to make them more comfortable. St. Clement discovered that the combination of moisture from perspiration and ground dampness coupled with pressure from his feet matted these tow fibers together and produced a cloth. After becoming bishop he set up groups of workers to develop felting operations. St. Clement became the patron saint for hatmakers, who extensively utilize felt to this day.

Today, hats are associated with felt, but it is generally presumed that all felt is made of wool. Originally, early shockproof felt was produced using animal fur (generally beaver fur). The fur was matted with other fibers—including wool—using heat, pressure, and moisture. The finest hats were of beaver, and men’s fine hats were often referred to as beavers. Beaver felt hats were made in the late Middle Ages and were much coveted. However, by the end of the fourteenth century many hatmakers produced them in the Low Countries thus driving down the price.

The North American continent was home to many of the beaver skins used in European hatmakers’ creations in the eighteenth and nineteenth centuries. North American Indians’ second-hand skins, replete with perspiration, felted most successfully and were in extraordinary demand for hatmaking in both the New and Old Worlds. The beaver hat was surpassed in popularity in the second half of the nineteenth century by the black silk hat, sometimes finished to resemble beaver and referred to as beaver-finished silk.

The steps included in making felt have changed little over time. Felted fabric is produced using heat, moisture, and pressure to mat and interlock the fibers. In the Middle Ages the hatmaker separated the fur from the hide by hand and applied pressure and warm water to the fabric to shrink it manually. While machinery is used today to accomplish many of these tasks, the processing requirements remain unchanged. One exception is that until the late nineteenth century mercury was used in the processing of felt for hatmaking. Mercury was discovered to have debilitating effects on the hatter causing a type of poisoning that led to tremors, hallucinations, and other psychotic symptoms. The term mad hatter is associated with the hatmaker because of the psychosis that stemmed from the mercury poisoning. Hats of wool felt remain quite popular and are primarily worn in the winter months.

The use of felt has enlarged over the past century. Crafts enthusiasts use it for all types of projects. Many teachers find it to be an easy fabric for children to handle because once it is cut the edges do not unravel as do woven fabrics. Industrial applications for felt have burgeoned, and felt is found in cars as well as production machinery.

Felt is produced from wool, which grips and mats easily, and a synthetic fiber that gives the felt some resilience and longevity. Typical fiber combinations for felt include wool and polyester or wool and nylon. Synthetics cannot be turned into felt by themselves but can be felted if they combine with wool.

Other raw materials used in the production of wool include steam, utilized during the stage in which the material is reduced in width and length and made thicker. Also, a weak sulfuric acid mixture is used in the thickening process. Soda ash (sodium chloride) is utilized to neutralize the sulfuric acid.

Quality control begins with the arrival of the materials. Materials are checked for quality and weight. Some companies purchase wool that has been scoured and baled; the purity of the bales is examined upon entry. Other important quality control checks include continuous monitoring of the carded webs, since the web sizes are important first steps in producing the desired length and width of the felt. Once the batts are shrunk in width and length, the company checks the weight, density, width, length, and evenness of the batts. When production is complete, visual checks may reveal that the surface of a batt is slightly uneven and additional pressing may occur to even out the surface. The acid baths are also very carefully monitored. The amount of time the fabric is in the acid bath is precisely calculated by weight and length of yard good, lest the piece is ruined. Finally, the company producing industrial felt has to check its goods against a governmental standard for the product. The government has determined that 16 lb (7.3 kg) density felt must be 1 in (2.5 cm) thick, 36 in (91.4 cm) wide, 36 in (91.4 cm) long, and weigh 16 lb (7.3 kg). If the felt weighs less than this, the fabric is not dense enough and does not meet government expectations for that grade of felt.

I discovered something wonderful over in Germany! Schnitzel! – kidding… No, I found heavy-weight industrial felt in a fabric store and was instantly in love! It is grey wool and 3mm thick, which makes a wonderful media for a variety of ‘making’ such as bags and purses, containers, footwear etc… I immediately put it to the test. Working and making with industrial felt is actually quite easy compared to usual sewing practices.

But first, what is felt? Felt is the short word for a variety of material that is made by the combining of fibres without knitting or weaving. The fibres are matted by some method of twisting or vibrating until they become so entangled with each other that they hold strong. It’s really the same as how one turns their hair to dreadlocks. Original machine parts felt dates back to as much as 6,500 BC. It can be hand made, manufactured or even made by having huge rolls dragged behind horses to matt the fibres.

Depending on the fibres and thickness it can even be used for furnishings. I just love how versatile it can be. See here for some very innovative work by Freya Sewell. There are interesting stories of mongolians pulling rolls of felting behind horses til strong and thick. That thick felt provides the protection on the walls of the yurt. Felt is breathable, warm, strong, but also tends to be light for it’s size.

As you can see, the fibres are very densely matted and have no direction. For that reason, it can be cut and will not unravel or fray. That makes less work of finishing edges! Another designer’s dream! I used a rotary cutter as well as a matt knife with straight edge. It allows for perfect edges. Using a cutting matt keeps it square and easily measured and protects your table.

Another of the major advantages of felt is that even though it is strong AND thick, it can usually still be sewn with a machine. That is one of the frustrating problems of leather; it is tough to sew on a regular sewing machine. My felt was 3mm and I had no problem sewing 2 thicknesses as the needle does not have a problem getting through. My other felt (polyester, I suspect) was thinner but denser and was still easy to sew. Due to it’s density and stiffness it was sewn on the ‘right sides’. That gives it an industrial charm.

Pop rivets come in a variety of lengths and sizes. They are unique as they work by pulling the material together from the right side. The rivet is inserted through the holes in the material thicknesses, a backup washer is inserted on the inside, and then the rivet gun pulls the shaft from the outside (the bulbous end is pulled through the end which anchors it) and the shaft breaks with a ‘pop’ and then comes out.

Hand-made felt is irregular and sometimes looks like thick skin because of its pleats. It does not go under a press so it is not flattened. This feature added to its extraordinary thickness gives felt a primitive aspect. It is a beautiful material that I love but with which I do not work.

It can be found in many different thicknesses from 2mm to 2cm. It is resistant over time and has a minimal aspect. That is why I have chosen to work with it.

Both types of sealing pad felt are nonwoven textiles and can both be clean-cut without fraying. That is why they do not need finishings such as hemming.