Different fibers have different strengths
Introduction
Our company carries a wide variety of carpet in a number of fibers: Nylon, Smartstrand, Polyester, and Wool. Manmade fibers are, more often than not, less expensive and have incredible stain-resistance for today's homes and offices. Wool is a natural fiber, of course, and has a number of benefits as well. Let's look close at each fiber to see what will be the better choice for your project.
Nylon
Nylon is a manmade fiber with a number of benefits. It has taken center stage in the industry due to its durability, longevity, and stain-resistance. It's not impossible to stain (in comparison to the top stain-resistance of Polyester), but it has very good stain-resistance, and therefore is a popular choice for new homeowners or homeowners wanting to upgrade their existing flooring. Nylon comes in a large number of cut-pile solid and fleck (multi-color), loops, and patterns. The above photo of a Tuftex fleck cut pile Nylon carpet was our best selling carpet in 2022 (still available!). Nylon is normally a soft and comfortable carpet to the touch, and the area of distinction with Nylon is its strength of durability. Three things dictate the ability of a carpet to look as good up to a decade from now as it does today, and those are: composition of the fiber (which Nylon has), fiber twist, and fiber density. As a general rule, a carpet with a tighter fiber density will look better over time than one which does not have as much density.
Smartstrand (Mohawk)
Smartstrand is a proprietary fiber available on select Mohawk carpets. This fiber is made with DuPont's Sorona Polymer and changed the game from adding a stain resistant treatment onto a fiber, to manufacturing the stain-resistant qualities into the fiber itself. This makes Smartstrand an extremely durable fiber, though it's not Nylon, it has a number of the same benefits as Nylon. It also, as mentioned, has great stain-resistance, and depending on the Smartstrand category, can be soft or very soft to the touch (seen in the new Smartstrand Silk and Smartstrand Silk Reserve carpets). The Silk line was also a leap forward in technology, with Mohawk offering a carpet made from 100's of tiny Smartstrand fibers combined into each strand of yarn. Smartstrand and Nylon are the top two contenders of industry fibers when it comes to durability, longevity, and comfortability.
Polyester
Introduced in the mid 1960's, Polyester came about two decades after the introduction of Nylon. Both man-made fibers, this meant Nylon and Polyester could be produced in a whole different manner than wool or cotton, which had scarcity depending on the economy and could have significant cost fluctuations. Man-made fibers were also more consistent in dyeing color and in consistency for many aspects. As Nylon and Polyester advanced, Nylon and Polyester divided in a few respects. Nylon was a longer lasting, or more durable fiber, whereas Polyester was more durable in stain resistance (some say it's impossible to stain) and cost less to manufacture. Wool continued to be available in the industry, but because of the above reasons, Polyester and Nylon soared in the American market through the 70's, 80's, and into present day. Polyester is a great choice if you want to carpet in a high-traffic residential area for a short period (getting ready to sell a home or flipping a rental unit). Polyester has a minimal price tag, has superior stain resistance (some say, proof), and will look good for a while. It won't look good as long as Nylon or Smartstrand, but it isn't intended to do so. For customers looking for a Polyester carpet, it delivers.
Wool
That's right. It's natural. And that is the biggest benefit of wool. This is a natural fiber, from the wool of sheep. It is renewable, sustainable, biodegradable, and, because it's a natural fiber, this is a great choice for those who know they have sensitivity to other fibers (rare, but occurs in some people). Wool is soft, durable, and has natural qualities to resist soiling. It may be more susceptible to stains, so ideally it should be in an area not prone to spills. Wool may be more expensive than Nylon or Smarstrand, depending on the model of carpet - some are and some are not. Wool may require a little more maintenance and should be cleaned by a professional who is experienced with cleaning wool carpet. It is possible to see loose wool fiber from time to time, as it is manufactured differently than man-made fibers. Wool can absorb moisture (when humidity levels are high) and release some moisture (when the air is dry), which can be beneficial in many applications, however, because you would never want it to be too humid in the area or too dry, it's proper to maintain a normal humidity level in the residence or commercial space with your carpet.
Summary
All of the above fibers have their benefits. In addition to 100% Nylon, 100% Smartstrand, 100% Polyester, and 100% Wool, you will also commonly see across the industry carpets which are a blend of two or more types of fibers. A blend is not necessarily a negative, and can actually be a positive, because it mixes the benefits of two or more fibers into a single carpet model, fortifying the benefits to the customer. Ask your flooring professional about the type of carpet you are most interested in, and they will be able to add even more specific guidance depending on your specific location and your specific project.