FR barrier fabric: technical FAQ

Straight answers to what mattress and upholstered furniture manufacturers actually ask about fire barrier fabric, flammability standards and fiber specifications.

What is a mattress fire barrier and where does it sit?

A fire barrier is a layer of fabric between the mattress ticking and the foam core. Its job is to keep an open flame from reaching the polyurethane foam, which is the actual fuel in a mattress fire. An unbarriered mattress can peak an order of magnitude above the 200 kW limit set by 16 CFR 1633; a working barrier brings the same construction under it.

What is the difference between 16 CFR 1632 and 16 CFR 1633?

1632 is the cigarette or smolder ignition standard, in force since 1973. 1633 is the open-flame standard, effective 2007, which tests a full mattress set against a twin burner and limits peak heat release to 200 kW and total heat release to 15 MJ in the first 10 minutes. A mattress sold in the United States must meet both. They test different ignition sources and a construction can pass one and fail the other.

What is 16 CFR 1640 and does it apply to mattresses?

It is the federal upholstered furniture flammability standard, which adopted California Technical Bulletin 117-2013 nationally. It applies to upholstered furniture and explicitly excludes mattresses and bedding, which stay under 1632 and 1633. If you make both mattresses and upholstered furniture you are working to two different rule sets.

How does a needle-punched FR barrier actually work?

The FR fiber does the work. Under heat, an inherently flame-resistant viscose forms a protective char rather than depolymerising into volatile fuel, and that char blocks oxygen going in and pyrolysis gas coming out. The polyester component melts and binds that char structure together so it holds its shape instead of crumbling away. This is why the fiber ratio matters at least as much as the basis weight: char yield scales with the FR fiber fraction, while the polyester fraction is both binder and fuel.

What is the difference between inherent and topical flame retardancy?

Inherent means the flame resistance is part of the fiber itself, incorporated during fiber production, and it cannot wash out, wear off or vary with coating application. Topical means a chemical treatment applied to finished fabric. Inherent systems are more consistent lot to lot and are generally the ones that survive tightening state chemical restrictions.

Is fiberglass still an option for mattress barriers?

Not in California after 1 January 2027, when AB 1059 bans textile fiberglass in mattresses, juvenile products and upholstered furniture. It also ends the AB 2998 exemption for non-foam components, bringing barrier fabrics under a 1,000 ppm flame retardant chemical limit. NW Fabrics has never used fiberglass in any construction.

What roll widths and weights does NW Fabrics make?

Needle-punched nonwoven roll goods from 0.4 - 1.0 oz/sqft (120 - 300 gsm) across the product line, with mattress FR barrier typically specified from 0.4 - 0.7 oz/sqft (120 - 215 gsm). Roll widths to 95 inches. Fiber system is FR viscose rayon / polyester.

What does oz/sqft mean and how does it convert to gsm?

Ounces per square foot is the customary US way to specify barrier weight; grams per square metre is used almost everywhere else, and by most of the import supply base. One oz/sqft equals about 305 gsm. So 0.5 oz/sqft is roughly 153 gsm and 1.0 oz/sqft is roughly 305 gsm. Quoting both units avoids a whole category of specification error.

What is LOI and why does it appear on a fiber spec?

Limiting oxygen index, measured per ASTM D2863, is the minimum percentage of oxygen in the atmosphere needed to sustain combustion of a material. Air is about 21 percent oxygen, so anything above roughly 21 will not readily sustain burning in air. FR viscose typically runs 28 to 32; ordinary viscose runs about 18 to 19. LOI is a functional measure, which is why it is the most useful single number on an incoming fiber certificate.

Do I have to retest my prototype if I switch barrier suppliers?

Almost always yes. 16 CFR 1633.4(b)(3) permits a component change without requalification only if you can demonstrate on an objectively reasonable basis that it will not cause the set to exceed the test criteria, and CPSC staff guidance recommends completing qualification tests with both suppliers barriers. NW Fabrics pays for 1633 testing for its manufacturing partners specifically to remove that cost.

What should a barrier fabric certificate of analysis actually tell me?

The test method and revision used, the reporting basis for fiber content (oven-dry or conditioned), fiber content with any inorganic flame retardant package identified separately, basis weight and width, lot and production date, and ideally a functional flammability result such as LOI or a vertical flame test. A bare percentage with no method and no basis is not something you can build a compliance file on.

Why does a chemical fiber-content test sometimes disagree with the label?

Because the standard method can be confounded by the flame retardant itself. AATCC 20A determines a viscose and polyester blend by dissolving the cellulose in sulfuric acid and weighing the residue as polyester. Silica-based flame retardant incorporated into FR viscose does not dissolve, so it stays in the residue and is counted as polyester. A perfectly on-spec blend can therefore report as substantially higher polyester than it is. ISO 1833-1 addresses this directly, noting the methods are not applicable where non-fibrous added matter cannot be removed.

Where is NW Fabrics fabric made?

At our plant at 9189 Winkler Drive, Suite E, Houston, TX 77017. The company was founded in 2016 and is family owned and owner operated.