Fleece, a synthetic polyester fabric with many of the properties of wool, first became popular in the 1990s. Its light weight and warmth made it ideal for outdoor use. Since then it has become a fashion material even though it is often made from recycled plastic bottles. Manufacturing fleece begins by crushing recycled polythene terephthalate (PET) bottles or containers into small chips, and then melting them down. The resulting liquid is then forced through small holes to produce threads that are used to make the fabric.
Collect used PET soda bottles or other containers. Sort the bottles by colour, separating green ones from clear ones.
Place the bottles in a sterilising bath. Dry the clean containers and crush them into small chips.
Wash the chips again, then bleach the clear chips. The green chips will remain green, and used for yarn that will be dyed a dark colour.
Heat the thoroughly dry chips in a vat, and force the material through very fine holes in a metal disk called a spinneret. As the liquid sprays out of the spinneret, it hardens into fibres, which are wound onto a heated spool. At this point, the fibres resemble a thick rope, and are called tow.
Pull the tow from the spool through heated rollers in a drawing machine until it is three or four times its original length. This step increases the strength of the fibre.
Pass the tow through a crimping machine, which gives it a crinkled texture. Dry it and cut it to lengths of several inches. The baled fibre at this point resembles wool.
Place the cut tow in a carding machine to align the fibres into rope-like strands, which are then coiled in containers. A spinning machine next twists the fibres into strands having much smaller diameters.
Immerse the yarn in a heated dye vat. After dyeing, the yarn is dried.
Knit the yarn into cloth.
Run the cloth through a napper, which raises the surface of the material. Following that, a shearing machine cuts the raised fibres to an even length.
Add waterproofing or any other desired chemical finishes, then cut the fabric into lengths.