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Effect of "Blistering" on the Ignition and Flammability of Painted Gypsum Wallboard.

pdf icon Effect of "Blistering" on the Ignition and Flammability of Painted Gypsum Wallboard. (516 K)
Mowrer, F. W.

NIST GCR 01-804; 15 p. January 2001.

Fire and Materials 2001. 7th International Conference and Exhibition. Proceedings. Interscience Communications Limited. January 22-24, 2001, San Francisco, CA, 197-208 pp, 2001.


National Institute of Standards and Technology, Gaithersburg, MD

Available from:

National Technical Information Service (NTIS), Technology Administration, U.S. Department of Commerce, Springfield, VA 22161.
Telephone: 1-800-553-6847 or 703-605-6000;
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wallboard; gypsum board; cone calorimeters; fire models; flame spread; paints


More than 300 gypsum wallboard samples coated with 0 to 8 layers of paint have been subjected to flammability testing in the Cone Calorimeter. Testing has been conducted with samples coated with either latex-based or oil-based interior paints and subjected to imposed heat fluxes ranging from 25 to 75 kW/m2. During some of the tests, "blistering" of the painted surface has been observed. This blistering phenomenon is most pronounced in samples coated with multiple layers of oil-based paint. As the number of coats of paint increases, blistering is observed at lower imposed heat fluxes. When blistering does occur, the time to ignition decreases significantly, typically by a factor of 3 to 4, when compared with samples that do not blister, while the burning duration remains approximately the same. The potential for upward flame spread on painted gypsum wallboard is addressed in terms of a modified version of the Quintiere flame spread model. The concept of a critical heat flux for upward flame spread is developed as a means to account for the race between ignition and burnout.