Abstract
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.
