Flame-retardant impregnants for woods based on alkaline silicates

The aim of this paper was to determine the fire performance of wood panels (Araucaria angustifolia) impregnated in a pressure vessel with post-cured alkaline silicates (water glasses). Several commercial silicates based on sodium ions and potassium ions with 3.0/1.0 and 3.5/1.0 silica/alkali molar ratios were selected. Various treatments for curing were applied for polymerization, creating metal silicate polymers of high water insolubility.Experimental panels were tested in a limiting oxygen chamber (limiting oxygen index) and in a two-foot tunnel (flame-spread index and panel consumption). Test results displayed a high fire-retardant efficiency of some post-cured alkaline silicates.