Over the years, brand name fiber manufactures and carpet mills that make their own in-house fibers have developed various shapes to achieve different performance characteristics for the different types of carpet.

This is a review of the evolution of the various fiber shapes. Fiber shapes have been re-engineered and improved; today we have four basic shapes that have survived the test of time. There are several different types of synthetic carpet fibers made, mainly olefin, polypropylene, polyester and its cousins, nylon 6 and nylon 6.6. You can learn more about the types of fibers in our article on fiber types. This paper focuses more on the actual shape of the fiber and how the shape affects performance.

A key principal in fiber performance is called light refraction. Carpet fibers are engineered to magnify color as light rays pass through the fiber. There is not as much color in the fiber as appears because as light passes through the fiber it magnifies the color making the fiber look more bright and brilliant.

Some fibers are softer, scratch easier, are distorted and damaged easier than other fibers. If the fiber is damaged it does not magnify the light as well causing the carpet to look worn, dirty and “uglied out.” “Uglied out” is a condition when the carpet looks matted, soiled, and dingy and you want to replace it because it does not look good. Often a carpet is replaced not because the carpet is worn out but because it is uglied out.

This can happen for a couple of reasons, one being the carpet is a low quality low performing carpet and just wears out quickly. Another reason would be that the carpet is not properly maintained and the fibers are damaged to a point that they do not properly magnify light properly.

Round Fibers:

Fiber Shapes

The first synthetic carpet fibers were round in shape, we quickly learned the round shape magnified scratches and soil. Carpet made with round shaped fibers looked much dirtier and more worn than they really were. This shape was quickly replaced with other shapes that had improved performance characteristics.

Trilobal Fibers:

Fiber Shapes

The trilobal fiber was invented to help defuse the magnification of soil and scratches that occurs with the round fiber.

Trilobal fibers are mainly used in residential carpet where the customer wants full and fluffy carpets compared to shorter harder commercial carpet. The industry says one of the better characteristics of a trilobal fiber is to add bulk and luster. You can get a more luxurious feel and look by using a trilobal fiber. Because the lobes of the fiber create bulk, you do not need to use as much raw material in the manufacturing process and carpets made with trilobal fibers tend to be less expensive than carpets made with other fiber shapes. This is because the other shapes require more material to create the same look and feel.

The biggest problem with trilobal fibers is the lobes or legs of the fibers can fold, bend and break causing the carpet to look gray and dingy. The light rays are blocked causing a dulling effect that makes the carpet look dirty and worn when it may not be. This wear is called “traffic lane gray” or “uglied out” and cleaning may temporarily improve the look of the carpet but will quickly flatten out looking worn and dirty again.

Delta and Modified Delta Shape:

Fiber Shapes

The delta fiber shape was engineered to have the strength and resilience of the round fiber shape and help hide soil like the trilobal shape. The delta shape gives you some bulk and luster like the trilobal but the lobes can still fold over, break off and trap soil. For this reason, the delta fiber was re-engineered and called a modified delta.

Fiber Shapes

The modified delta shape is mainly used in commercial carpet because it does not create the bulk and luster achieved with the trilobal shape. It takes more fiber to create the same look. Most commercial carpets are manufactured with lower and tighter loops so they do not need to create the illusion of bulk and luster.

Carpets manufactured with the delta or modified delta shape usually perform better than carpets made with the trilobal shape. Quality commercial carpets tend to cost more because more material is required to manufacture quality carpet. The more material the more expensive the product costs and in most cases with proper maintenance will outperform other carpets.

You want the fiber to keep its shape and not trap soil. Commercial carpets get 100’s and 1,000’s of foot traffics per day where a residential carpet may be walked on 30, 50 or 100 times a day. Using a residential type fiber in a commercial application tends to show early signs of wear and tear.

Four -Hole Hallow Filament Fibers:

Fiber Shapes

Most commercial carpet mills agree that the four hole hallow filament fiber is the best performing fiber in the industry. It is a four-sided fiber, with rounded corners and has four holes running through the center.

It performed well because it does not have the peaks and valleys that fold over and trap soil. The square shape is easier to clean because there are not crevasses’ for the dirt and soil to get stuck in. Independent laboratory tests show this fiber shape releases soils easier when vacuumed or cleaned.

Carpet made with this fiber may cost a bit more upfront than carpet made with other fibers but in most cases it will last longer and is easier to clean. This means your cost per year will be reduced and carpets with this fiber shape should in the end save you money over time.