Carpet And Rug Construction
Understanding carpet construction
The look and performance of a particular carpet is determined by its construction, which may be loop, cut or combinations of the two. In corridors, lobbies, offices, classrooms, hotel rooms, patient care facilities and other public areas, loop piles of low, dense construction tend to retain their appearance and resiliency and, generally, provide a better surface for the rolling traffic of wheel chairs or food carts. Cut pile or cut and loop pile carpet are very good choices for administration areas, libraries, individual offices and boardrooms.
Various types of high performance backing systems have additional advantages, including higher tuft binds, added stability, imperviousness to moisture and resistance to edge raveling. Consideration should be given to the functional needs of a particular area.
Understanding carpet construction assists in specifying elements that will provide the best performance in a particular location. Commercial carpet is primarily manufactured by tufting or weaving. Each process will produce quality floor coverings, but tufted carpet accounts for 95 percent of all carpet construction. Both tufting and woven manufacturing are efficient and employ advanced technologically to provide capability for a myriad of patterns and floor covering.
Tufted: Tufting is the process of creating textiles, especially carpet, on specialized multi-needle sewing machines. Several hundred needles stitch hundreds of rows of pile yarn tufts through a backing fabric called the primary backing. The needles push yarn through a primary backing fabric, where a loop holds the yarn in place to form a tuft as the needle is removed. The yarn is caught by loopers and held in place for loop-pile carpet or cut by blades for cut-pile carpet. Next, secondary backings of various types are applied to render a variety of performance properties.
Here are some key steps in the tufting process:
Woven: Woven carpet is created on looms by simultaneously interlacing face yarns and backing yarns into a complete product, thereby eliminating the need for a secondary backing. A small amount of latex-back coating is usually applied for bulk. Principal variations of woven carpet include velvet, Wilton and Axminster.
Facts on fiber
For commercial applications, approximately 80 to 82 percent will be nylon, 8 to 10 percent will be olefin and 8 percent will be wool.
Nylon: Nylon is by far the most prevalent fiber used in commercial carpets. Nylon is excellent in wearability, abrasion resistance and resilience. It is easily cleaned and can be stain resistant. Nylon fibers withstand the weight and movement of furniture and are generally good for all traffic areas.
Olefin: Olefin (polypropylene) is used where resistance to sunlight fading and chemicals is more important than durability to traffic. Olefin is only available as a solution dyed BCF fiber, is colorfast, resists fading, generates low levels of static electricity and is resistant to acid-based stains.
Wool: Wool is a natural staple fiber, is durable, resilient and self-extinguishing when burned. It is noted for its luxury and performance because it is soft, has high bulk and is available in many colors and patterns. Because of its higher cost, wool is usually used as a decorative accent and in lower traffic areas.
Yarns can be either bulked continuous filament (BCF) or staple. Polymer is forced through forced through a spinneret (extrusion) in uninterrupted filaments, which are then formed into a bulked continuous filament yarn. These fibers may be chopped into short fibers and then spun into staple yarn, twisted, and set with heat to hold the twist. A tighter twist is more important in cut pile because it resists the ends of the yarn from untwisting and matting together during wear and cleanings.
Facts on Backings
All carpet has some type of backing system or chemistry that helps keep the tufts in place. Backing systems are made from a variety of materials and may also come with various kinds of protective treatments (such as anti-microbial or anti-stain) or beneficial properties (such as anti-static).
The methods and chemicals used depend upon the performance requirements of the backing and the carpet. These decisions will be based upon the specifier’s performance considerations and the manufacturer’s recommendations. Performance considerations are especially important for demanding environments. It’s important that the specifier identify the highest priority needs for how the carpet will perform, whether that is wear and tear, moisture-resistance, or heavy foot traffic. The manufacturers’ end use recommendations help determine which product will meet the established performance expectations.
Carpet backing systems contain the following elements: a primary backing, a chemical adhesive, and often a secondary backing. In the most common system, the yarn is secured into the primary backing by synthetic latex, and a secondary backing (or cushion) is attached with a bonding agent or adhesive to provide further pile-yarn stability and to add dimensional stability to the carpet structure.
Whether a carpet has a secondary backing depends upon the end use of the carpet and the location of the installation. Carpet for high performance end use generally has a primary backing and a secondary backing. Carpet for low traffic areas may have only a coating of latex, a secondary backing or a cushion attached to the primary polypropylene backing.