Thermoplastic polyester fibers are used extensively in nonwoven automotive interior, construction and industrial applications; upholstery and housewares; among the many other end-uses. The need for consistent and reproducible flame-retardant polyesters has never been more urgent. However, over the past 15 years, the nature of flame retardants used by the industry has changed dramatically. Many of those used adversely affected the short-term and long-term mechanical properties. Others created major smoking problems during spinning operations, while still others broke down during processing. The random performance of many of those additives created opportunities for various vendors to introduce reactive additives to be added during the polymerization of thermoplastic polyesters. In all cases, the level of the flame retardant added to achieve the required performance ranged from 5-7% in relation to the total weight of the fabric. Because most systems were provided in masterbatch form, the fiber producer could not confirm the actual final levels throughout the needlepunched nonwoven, which therefore exhibited random performance. Over time, cost and performance changed, and the requirements for tougher and cheaper performing additives dominated the market globally. Pressures on cost and the passage of more stringent flame-retardant specifications created additional demands by the market. Today, a flame-retardant additive for nonwovens must meet the following requirements: • The product must not adversely affect the natural color or coloration of the fiber • It must be non-smoking during fiber production • It must have no adverse effects on short- and long-term fiber properties • It must have no adverse effect on ultraviolet (UV) durability • It must pass the newest standards in a global market Two test methods prevail: the National Fire Protection Association's NFPA-701 vertical burn test; and the more difficult Federal Aviation Administration's (FAA's) standard vertical flammability test in accordance with Federal Aviation Regulation (FAR) 25.853 (a) for compartment interiors. Both tests call for self-extinguishing flame out in less than two seconds, and no drip and no smoking during testing. Burn length, burn time and dripping time in the FAA standard are less than 8 inches, 15 seconds and 5 seconds, respectively. In addition, the flame retardant must not affect the physical properties of the nonwoven or adversely affect yellowing on UV exposure. After many years of research and development and extensive analytical testing of the active additives and masterbatches produced, the polyester fiber manufacturer's final product, and the nonwoven end-product, researchers at Charlotte-based Stabilization Technologies LLC have finally determined those factors that affect performance, as well as those parameters that allow lower levels of active additive in the nonwoven to achieve the required performance and a cost-benefit performance for the industry that makes the product competitive in the global market today. Today, a flame-retardant system finally exists that can be used at less than 3% in relation to total weight in the polyester fiber and that passes both FAA and NFPA-701 vertical burn tests, including instantaneous flame out, no smoke and no drip criteria. The product has no adverse effects on short- or long-term physical properties, or on UV durability; causes no discoloration or antagonism with colorants used in polyesters; and has no restrictions on use for the majority of applications for a flame-retardant polyester today in a global market. The price and economics and cost-benefit performance is higher and more consistent than any flame retardant system in use today. The product is offered by Phoenix Plastics LP under the trade name Cel-Span® 789. (Author: Joe Webster is president of Stabilization Technologies LLC)