Fire Safety Science Digital Archive

The flammability and dehydration of painted gypsum wallboard (GWB) exposed to fire heat fluxes are investigated. Painted GWB samples are subjected to constant incident heat fluxes ranging from 25 to 75 kW/m² for periods ranging from 5 to 15 minutes in the Cone Calorimeter. A number of coats of latex interior paint, including 0, 2, 4, 6 and 8 coats, are applied over a single coat of latex primer to the exposed surface of 15.9-mm (518-in.) thick type X GWB. A model is used to evaluate the potential for flame spread based on the Cone Calorimeter results. A two-step dehydration model based on a finite difference formulation is described for GWB. Experimental results indicate a distinct dehydration front can be observed by visual inspection; further analysis is needed to determine the composition of the GWB on each side of this front.