So, you have recently heard about flame retardancy (perhaps from a fire marshal who asked you if you have a flame certificate showing that your digital backdrop is flame retardant, or you were told that the new custom stage curtains that you plan to purchase need to be flame retardant), but you don’t have a clue what that means.  No need to worry – this blog post contains the information you need to become familiar with this complex subject.

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Fabric Flammability

Fabric flammability is an important issue to consider, especially for drapery that will be used in a public space such as a school, theatre or special event venue, since government regulations require that drapery fabrics used in such spaces be certified as fire retardant. Although all fabric will burn, some are naturally more resistant to fire than others. Those that are more flammable can have their fire resistance drastically improved by treatment with flame retardant chemicals.

Certain synthetic fibers are extremely flame resistant, including glass fibers and modacrylic. Other synthetics, including certain polyesters, are slow to ignite and may even self-extinguish. However, once synthetic fabrics ignite, they will melt rather than flame. The resulting substance can lead to severe burns if it comes into contact with the skin.

Natural fibers typically do not melt. Wool and silk burn slowly, are difficult to ignite, and may self-extinguish. With other untreated natural fabrics, such as cotton and linen, the fabric can ignite quickly, resulting in a fast moving flame spread. Fabrics that include a combination of natural and synthetic fibers, such as polyester-cotton blends, can be particularly troublesome, as they combine the fast ignition and flame spread of the natural fiber with the melting aspect of the synthetic fiber.

The ignition and burn factors of fabric are also affected by the weight and weave of the fabric. Lightweight, loose weave fabrics will burn more quickly than heavier fabrics with a tight weave. In addition, fabric flammability can also be affected by the fabric’s surface texture, with napped fabrics (such as velvets and velours) igniting more easily than fabrics with a smooth surface.

Fire Retardancy of Fabrics

The good news is that the flammability of fabric can often be drastically reduced through the use of fire retardants. Many natural fibers, including cotton, can be topically treated with a chemical that reduces the fabric’s flammability to the extent that it becomes nearly non-combustible. During a fire, the chemical reacts with the gases and tars generated naturally by the fabric, converting the gases and tars to carbon char, thus drastically slowing the fabric’s burning rate.

Some polyester fabrics are considered permanently flame retardant. This is because the fabrics are manufactured utilizing fibers for which the flame retardant properties are built directly into the molecular structure of the fibers. Fabrics manufactured utilizing Trevira™ and Avora™ polyester fibers are considered inherently or permanently fire retardant. Other synthetic fabrics may be considered durably fire retardant, fire retardant, or non-fire retardant. “Durably fire retardant” refers to a process in which polyesters are chemically treated during the manufacturing process with a non-water soluble chemical. In other cases, synthetic fabrics may be topically treated with chemicals after the manufacturing process (in the same manner as natural fibers such as cotton), or may be untreated (or untreatable) and therefore considered non-flame retardant.

When a fabric is designated as “inherently flame retardant,” “permanently flame retardant,” or “durably flame retardant,” the flame retardancy will typically last for the life of the fabric, as long as the fabric is properly maintained. The drapery can be laundered or dry-cleaned as recommended by the drapery manufacturer. In the case of fabrics that are designated as “flame retardant,” that have been topically treated with chemicals, the flame retardancy of the fabric will dissipate over time, particularly with repeated cleaning. These fabrics must be dry-cleaned with a non-liquid cleaning agent. Typically, the flame retardancy of topically treated fabric is certified for one year, though the actual length of time in which the treatment remains effective will vary based on the number of times the drapery is dry-cleaned and the environmental conditions of the location in which the drapery is used. It is recommended that drapery be re-tested for flame retardancy on an annual basis, and topically treated by a qualified professional as needed. 

Flame Retardancy Regulations

In the United States, there is no federal law regarding fabric flammability.  Instead, most states have instituted laws requiring that fabric used as hanging drapery in public spaces must meet NFPA 701 and/or NFPA 705 standards, created by an industry group, the National Fire Protection Association.  To meet these standards, fabrics are laboratory tested (NFPA 701) or field tested (NFPA 705). There are a number of factors involved in these tests, but essentially samples of the fabrics are set on fire and must self-extinguish within a certain amount of time.

Although most states and cities require that drapery (and other hanging fabrics) are certified to meet NFPA 701 / NFPA 705, there are a few exceptions. California law requires that fabrics meet a different standard, Title 19, with a similar (though not identical) testing method, and that fabrics, flame retardancy chemicals, and flame retardancy applicators / testers be registered with the Office of the State Fire Marshal. Though New York City regulations are based on NFPA 701 standards, that city has its own specific requirements, as does Boston.

Internationally, flame retardancy regulations vary widely.  In Europe alone, there are different regulations in the UK, Germany, and France, just to name a few. Australia has its own regulations as well.  There is no international standard for fabric flame retardancy.

Certification of Flame Retardancy

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When purchasing custom stage curtains or flame retardant fabric, always request a Certificate of Flame Retardancy from the drapery or fabric supplier.  This certificate (commonly referred to as a Flame Certificate) certifies that the fabric (as a sewn drape or as raw fabric) meets specific flame retardancy standards.  In the United States, this usually means that the fabric meets NFPA 701 standards.  Some (but not all) suppliers can also certify for California standards and/or New York City requirements. Occasionally, a supplier can certify a fabric for another country (such as the UK or Germany), but this is the exception rather than the norm.

A Certificate of Flame Retardancy is typically valid for one year, after which it is recommended that the fabric or curtains be re-tested for flame retardancy.  This is because a variety of conditions can affect the flame retardancy of fabric (even fabric that has been certified as inherently flame retardant).  Depending on the fabric and the type of flame retardancy (FR, DFR, PFR, or IFR), a fabric’s flame retardancy can be affected by a number of factors, including laundering, repeated dry cleaning, dust accumulation, use of pyrotechnic chemicals near the drape, and more. Therefore, it is prudent (and some fire marshals require) to have the drapery tested and re-certified periodically by a certified flame retardancy applicator / tester, and to retreat or replace any drapery that does not pass periodic retesting.