Fire retardant chemicals composed of trimethylol melamine (TM) -boric
acid (B) or -phosphoric (P) and/or -dicyandiamide (D) were applied to
the surfaces of plywood followed by hot pressing. The effectiveness of
these various treatments were evaluated based on the incombustibility
, leachability, and termite resistance of the treated plywoods. All tr
eated specimens had better fire-retardant properties than the untreate
d ones, and similar improvement were observed even after a deteriorati
ve pretreatment of dipping in 50 degrees C warm water for 30 minutes p
rior to testing. The specimens treated with TMP combinations had bette
r improvements in the incombustible properties, in terms of ignition t
ime, after-flaming time, glowing time, weight loss, and char length. U
nleached specimens treated with boric acid had the best termite resist
ance, followed by TMB and TMDB combinations. In all cases, trimethylol
melamine appeared to have a profound effect in keeping the damage to
lower levels after leaching. Observation by ion chromatography reveale
d that trimethylol melamine was effective in slowing down boron and ph
osphorus leaching even after several cycles of a severe leaching proce
dure.