Nylon continues to be the most popular choice, though its share of the market keeps slipping, mostly to olefin. Nylon has good resilience, soil resistance, abrasion retention, durability, and color retention. However, it is readily stained by acid dyes and fades in prolonged sunlight. Nylon is severely damaged by strong acids such as battery acid and strong toilet bowl cleaners. Its stain resistance properties can be improved through use of stainblockers at the mill and by application by the cleaner of fluorochemical topicals such as Scotchgard™ Brand Carpet and Upholstery Protector or DuPont Teflon^® Advanced Carpet Protector. Solution dyed nylon is an excellent choice where durability and stain resistance are both important factors, such as in nursing homes, hospitals, schools, auto showrooms, kitchens and restaurants.

There are five generations in nylon fiber:

Olefin continues to grow in popularity due to its lower cost and its consequent common use in berber. Olefin has excellent stain resistance, durability, chemical resistance, and fade resistance. However, it has virtually no resilience at all (it severely mats), and it very strongly attracts oily soil, which sometimes requires more aggressive cleaning. Its lower melting point can be a problem where furniture is dragged across it resulting in damaged fibers and is easily damaged by heel marks. Low profile level-loop olefin is a good choice where stain resistance is critical, such as in nursing homes, apartment buildings, grocery stores, etc. Olefin berber should never be installed on stairs or in high-traffic situations or where there is a lot of oily soil.

Olefin is used in most Berber carpets or for use where a less expensive product is required and life expectancy and long-term appearance are unimportant. Olefin is the fiber of choice to use outdoors. Olefin should NEVER be used where the primary soil is oil; for example, olefin should never be used in a car showroom.

 The reasons for checking for olefin are usually due to a complaint on matting or rapid resoiling (especially in oily environments), or the presence of a very stubborn stain that could be treated with chlorine bleach.

 Wool is too expensive to be practical in most installations plus it has poor stain resistance, especially to proteins such as urine and blood. The dyes in wool are more readily damaged and browning can occur if not properly cleaned. Since wool holds about 30% of its weight in water, it dries more slowly than nylon and is more difficult to extract in a water-damage job. Also, since wool is a protein, enzyme-based deodorizers and spotters should be used cautiously on it. Removal of stains is more difficult because the dyes and the fiber itself are so easily compromised. Since it is a natural fiber, mold, mildew, and insects can be a problem. However, it has excellent soil-hiding quality, is extremely durable and has a very soft luxurious "hand."

Polyester (PET) had been gaining market share, but is no longer. It had been gaining because it was easily recycled from 2-liter soda pop bottles (a good “talking point” to environmentally conscious consumers) and because it too is inherently stain resistant. Polyester carpets are soft to the touch. Like olefin, it has very poor resilience, which obviates its use in high traffic areas and it readily attracts oily soils.

Natural fibers made from organic sources that have not been chemically altered include wool, cotton, silk, sea grass, jute, and hemp. Natural fibers require more drying time because they are very absorbent, are more easily damaged by chemicals, shrink, stain easily, water spot, fade, and are readily attacked by mold and insects.

Silk is the only natural filament fiber. The fibers usually are about 1000 feet long. It is a protein fiber obtained by unreeling the cocoons of various silkworms. Characterized by a very high sheen, silk is very sensitive to alkali, sunlight, etc., and tends to yellow when exposed to alkaline detergents. Dye loss, yellowing, and ringing are common problems when cleaning silk. Silk is normally dry-cleaned. Wet cleaning is very risky because of the possibility of water spotting and watermarks. If silk is wet cleaned, only use a neutral detergent. The absorption of water breaks the bonds in the silk fiber and causes silk to lose approximately 20% of its strength. “Washable silk” results from a modification in the dye or a resin treatment to prevent fiber degradation. See the glossary for more detailed information.