Yarn Construction

A carpet yarn may be a single yarn (ply) or several yarns twisted together, forming a multiple-plied yarn (two-ply yarn, four-ply yarn). Carpet yarns are more durable if they are heat-set. Yarn size and weight are referred to as denier. Denier is the weight in grams of a piece of yarn 9,000 meters long (about .6 mile). The higher the denier numbers the larger the diameter of the yarn.

The amount of fibre (often referred to as face fibre) used per square yard of carpeting is the weight referred to in the manufacturer's specifications. This is sometimes given on the carpet sample. This weight is directly related to the durability of the carpeting. A 20- to 24-ounce nylon usually "wears" from eight to 10 years. Commercial-grade carpeting ranges in weight from 22 to 46 ounces or more usually given as per square yard.

HUD (Housing and Urban Development), a division of the Federal Housing Administration, uses the following formula to determine carpet density:

Pile yarn weight (oz/yd.) x 36 = carpet pile densityaverage pile height.

The higher the resultant numbers the higher the carpet pile density. The denser the carpet, the more durable it will be. Select a density level suitable for the traffic level where the carpet will be used.

Yarns may be made of filament or staple fibres. Filaments are long fibre strands measured in miles. They often are referred to as continuous filament fibres. Silk is the only natural filament fiber. A monofilament yarn is made of a single fibre filament. A multi-filament yarn is made of multiple fiber filaments. These may or may not be twisted together. When twisted and heat-set, they usually are more durable for floor coverings.

Staple fibres are short fibres measured in inches or fractions thereof. Staple fibres may be natural or manufactured and are spun together to make longer yarns. Because of the short lengths of fibres, staple yarns may be slightly more prone to fussing and pilling than filament yarns. A process called parallel spinning produces seven-inch or longer staple yarns that has increased the performance of short staple in carpet construction.