Carpet fiber is the single largest factor determining the look, feel, durability, and stain performance of a carpet. The fiber type, combined with the construction method and density of tufts, dictates how a carpet will perform over a 10- to 20-year lifespan.
Nylon 6 and Nylon 6,6
Nylon is the most widely used synthetic carpet fiber, accounting for roughly 60 percent of the US residential carpet market. It is available in two molecular forms. Nylon 6, produced by polymerizing caprolactam, has a slightly more open molecular structure and can be recycled through a depolymerization process back into caprolactam monomer. Shaw's EverTouch and Mohawk's Wear-Dated are common nylon 6 brands. Nylon 6,6, made from hexamethylene diamine and adipic acid, has a tighter crystalline structure that gives it marginally better resilience and crush resistance. It is produced primarily by Invista under the Stainmaster and Antron brands. Both nylons accept acid-dye stain blockers that bond to dye sites in the fiber, providing permanent stain resistance that does not wash off.
Polyester (PET)
Polyester carpet fiber, made from polyethylene terephthalate, is produced largely from recycled plastic bottles. It is inherently stain-resistant without chemical treatments because it lacks the amine dye sites that absorb stains in nylon. PET has a softer hand than nylon and is less expensive to produce. Its weakness is resilience: polyester fibers are more likely to mat and crush in high-traffic paths. For this reason, PET carpet is best suited to bedrooms and low-traffic areas. Mohawk's EverStrand and Shaw's ClearTouch are major PET brands.
Triexta (PTT)
Triexta, or polytrimethylene terephthalate, is the newest major carpet fiber, commercialized by DuPont in 2009 under the Sorona brand and now produced by Mohawk as SmartStrand. Triexta is made from 37 percent bio-based corn glucose. It combines the inherent stain resistance of polyester with resilience that rivals nylon 6,6. Independent wear testing has positioned SmartStrand as one of the highest-performing residential carpet fibers available.
Wool
Wool is the traditional premium carpet fiber. It is naturally flame-resistant due to its high nitrogen and moisture content, and its microscopic scales give it a unique ability to hide soil. Wool carpets are sold by face weight, typically ranging from 30 oz to 60 oz per square yard in residential products. The downside is cost, with wool commanding 3 to 5 times the price of a comparable nylon carpet.
Key Measurements
Face weight, expressed in ounces per square yard, is the weight of fiber above the backing. Residential cut-pile carpets typically fall between 25 oz and 50 oz. More important than face weight alone is density: the number of tufts per square inch. A high-density carpet with moderate face weight will outperform a low-density carpet with high face weight. Twist count, measured in turns per inch of yarn, affects how well a cut-pile carpet retains its texture. A twist of 4.5 to 6.0 turns per inch is standard for residential Saxony and frieze styles.
Pile Styles
Berber carpet, named after the hand-knotted wool carpets of North Africa, is a loop-pile construction using thicker yarn with visible flecks of color. Cut-pile styles include Saxony, with a smooth, even surface and a formal appearance; textured plush, where yarns are heat-set with alternating twist directions to hide footprints; and frieze, a high-twist shag with a curled, casual texture. Multi-level loop carpets combine loops of different heights to create sculpted patterns.