Yutaka Kataoka

Combustibility of fire-retardant impregnated and surface-coated wood after 5 years of natural weathering

The weatherability and combustibility of fire-retardant-impregnated wood during natural weathering for up to 60 months were evaluated. Fire-retardant chemicals used were modified guanidine phosphate with phenolic additives in order to retain chemicals against leaching. The ability of coating was also examined using four solvent-born coating systems:1 penetrating;semi-transparent(brown), 2 thin-film-forming;semi-transparent(brown), 3 film-forming;opaque(white), 4 film-forming;transparent. The systems 1 and 2 consisted of 2 or 3-coat application of each single coating composition, whereas 3 and 4 employed specific wood-sealers as an undercoat to stabilize the surface of wood prior to the application of topcoat. Phenolic additives were effective to maintain chemical retention for a certain period. After 60-month-natural weathering, coated specimens and uncoated specimen were at a quasi-non-combustible material level and a fire-retardant material level, respectively. Fire performance of specimens coated with 3 and 4 were better than 1 and 2.