Tufted carpet uses multi-needle sewing machines that stitch rows of the top fiber to the primary backing. Tufted carpet appears as cut pile or loops. Woven carpeting weaves or interlaces the top yarns with the bottom yarns on a loom. This carpet doesn’t need a secondary backing, but often has a latex coating applied for bulk. Manufacturers use latex as an adhesive or glue and as a coating for thickness to extend the carpet’s life.
Carpet has a primary backing, a chemical adhesive and a secondary backing. The manufacturing process holds the yarn to the primary backing with synthetic latex. The secondary backing adds bulk and is a cushion attached with an adhesive or bonding agent. Secondary backing is often made of woven polypropylene. Carpeting for low-traffic areas may have a layer of latex with no secondary backing.
Carpet manufacturers apply latex to carpet in two layers. The manufacturing process applies the first layer to the back of the carpet. A blade forces the latex into the carpet back to lock the yarn into the primary backing. The second application of latex holds the secondary backing to the primary backing surface, making the carpet more stable. Manufacturers cure the latex coating in an oven.
Other Carpet Allergens
Carpet contains artificial dyes, chemical stain repellents, antistatic sprays, antimicrobial products, fire retardants, polyvinyl chloride and vinyl, along with the surface construction materials. Older carpets may have absorbed odors and chemicals that release over time. Older carpets also may contain toxic products that government regulators have removed from the market. Both old and new carpets emit odors that can cause an allergic reaction. The new carpet smell is from 4-PC, a byproduct of latex. The U.S. Environmental Protection Agency reports that carpet manufacturers have made progress in chemical emissions in new carpets. The Carpet and Rug Institute Green Label Plus program specifies emissions limits from the carpet, cushion and adhesive used in installation. If you are allergic, select a carpet manufactured by a Green Label Plus carpet maker.