Fire Retardancy of Fire-retardant-impregnated Wood after Natural Weathering I.

Effects of chemical types and coatings at up to 60-months of exposure

Abstract

Fire-retardant-treated (FRT) woods were tested for natural weathering for up to 60 months at three places in Japan. Water-soluble and leach- resistant fire-retardants were used for the FRT woods. Half of the FRT woods were coated with high durability paint, using a combination of fluorine resin-based and polybutadiene-based paints. Fire retardancy of uncoated FRT woods decreased after 3 months for the water-soluble fire retardant and after 12 months for the leach-resistant fire retardant. The change in fire-retardant retention of uncoated FRT woods after weathering indicated that the decrease in fire retardancy had been strongly influenced by the resistance of fire retardants to leaching. Coated FRT wood that used both fire retardants maintained fire retardancy for up to 60 months. However, coated FRT wood made with water-soluble fire retardants led to the coat being separated from the FRT wood and a decrease in fire-retardant retention after 36 months.