Learn all about polyester threads Imagine a product so versatile that it is in water bottles, clothing, carpets, curtains, sheets, wall coverings, upholstery, hoses, power belts, ropes, threads, tire cord, sails, floppy disk liners, filling for pillows and furniture, and it is also used to replace or reinforce damaged body tissue. Such is the convenience of polyester. Polyester can be in the form of plastics and fibers. Polyester materials are the polymers that make the shatterproof plastic bottles that hold bottled water and soft drinks. And you know those fancy balloons with the cute messages imprinted on them? They are also made of polyester, more specifically, a sandwich composed of Mylar and aluminum foil. Our Glitter thread is made with a similar mylar/polyester blend. The most common type of polyester for fiber purposes is poly ethylene terephthalate, or simply PET. (This is also the same substance used for many soft drink bottles.) Polyester fibers are created by extrusion, a process of forcing a thick, sticky liquid (about the consistency of cold honey) through the tiny holes of a spinneret, a device that looks like a shower head, to form continuous filaments of semi-solid polymer. Depending on the number of holes, monofilaments (one hole) or multifilaments (several holes) are produced. These fibers can be extruded in different cross-sectional shapes (round, trilobal, pentagonal, octagonal, and others), resulting in different types of threads. Each shape results in a different sheen or texture.   Main types of polyester thread Corespun polyester threads are a combination of a filament polyester core thread wrapped in spun polyester. It is also known as 'Poly-core spun-poly', "P/P", and "PC/SP" thread. The benefit of using a core spun polyester thread like OMNI or OMNI-V, is the added strength that the filament core adds. OMNI and OMNI-V are favorites for quilting with their matte finish and strong tensile strength. Filament polyester is a continuous fiber thread. Some hear the word filament and incorrectly assume it is monofilament. Monofilament, which looks like fishing line, is just one type of filament thread. It is a single (mono) strand thread. MonoPoly is an example of a monofilament thread. Other filament threads are multiple filaments, which consist of two or three strands twisted together. This is the largest category of filament polyester. Multi-filament strands are smooth and lint free but are not transparent. The advantage of a lint-free thread is a cleaner machine and less maintenance. The Bottom Line and So Fine! are examples of this filament polyester thread. Trilobal polyester is a multiple filament, twisted, high-sheen continuous fiber thread. It has the bright appearance of rayon or silk, but the advantages of a polyester fiber. Triangular shaped fibers reflect more light and give an attractive sparkle to textiles. Our Magnifico and Fantastico thread lines are both trilobal polyester threads. Spun polyester threads are made by spinning or twisting together shorter lengths of polyester fibers. This is similar to the way cotton threads are made. These short fibers are then twisted together to produce a thread of the desired size. Spun polyester threads give the look of a cotton thread, but have more elasticity. Spun polyester is economical to produce and is usually a low-cost thread. We don't recommend spun polyester for quilting, as it is not as strong as corespun, filament, or trilobal polyester threads. Bonded Polyester is a strong polyester thread used for upholstery applications. Since polyester has fantastic UV resistance, bonded polyester is commonly used for outdoor furnishings and automotive upholstery. A special resin coating adds strength and helps reduce friction when stitched at high speeds. Polyester fibers recover quickly after extension (the term elongation describes the stretch and recovery) and absorb very little moisture. Polyester is heat resistant (dryer and iron safe), with a melting temperature of about 480º F (in comparison, nylon starts to yellow at 350º F and melts at about 415º F). Polyester fibers are colorfast, resistant to chemicals, and can be washed or dry-cleaned with most common cleaning solvents.