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Evaluating Smoldering Behavior of Fire-Blocking Barrier Fabrics



Shonali Nazare, William M. Pitts, Szabolcs Matko, Rick D. Davis


This study reports on the smoldering propensity of commercially available barrier fabrics (BFs) in a small-scale upholstered seating mock-up configuration. Most commercially available BFs are smolder resistant when tested alone over a standard flexible polyurethane foam (FPUF). However, when covered with a smolder-prone cover fabric (CF), most BFs fail the smoldering ignition test described in CPSC’s proposed standard 16 CFR 1634. Results of this study suggest that the smolder-prone CFs when placed on top of a number of BFs are capable of releasing sufficient heat to initiate the char-oxidation smoldering process of some of the BFs and subsequently transmit the heat to the underlying FPUF. A smoldering index for BFs has been derived from char volume fraction (CVF) of the FPUF by varying the BF component in the FPUF/BF/CF mock-up systems while holding the other two components constant. Out of the 20 BFs tested in this study, mock-ups with five BFs self-extinguished and passed the smoldering ignition test criterion as described in the proposed 16 CFR 1634. The smoldering index for these BFs was zero. BFs with smoldering index of 1 or more resulted in sustained smoldering in the FPUF. The smoldering propensity of BFs and the amount of heat transmitted to the FPUF varies depending on the BF structure, fiber content, air permeability, and bulk density. Flame retardant treatments and use of char forming fibers have shown a greater tendency for BF smolder in the presence of the smolder-prone CF. BFs with char-forming fiber bends have greater smoldering propensity as compared to BFs with low charring fiber blends. The lower the smoldering propensity of the BF, the less likely is the development of sustained smoldering in the FPUF.
Technical Note (NIST TN) -


Barrier fabrics, furniture flammability, smoldering, flexible polyurethane foam


Nazare, S. , Pitts, W. , Matko, S. and Davis, R. (2015), Evaluating Smoldering Behavior of Fire-Blocking Barrier Fabrics, Technical Note (NIST TN), National Institute of Standards and Technology, Gaithersburg, MD, [online], (Accessed May 30, 2024)


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Created January 29, 2015, Updated November 10, 2018