Increased dimensional stability of Chinese fir through steam-heat treatment

Chinese Fir is one of the most commonly planted tree species in China. As a fast-growing species, the main drawback is dimensional instability, which limits its applications. Steam-heat treatment is one of the effective methods to improve the dimensional stability of wood. Heartwood and sapwood of Chinese fir were treated using thermal modification with steam that was used as a heating medium and a shielding gas at temperatures ranging from 170 to 230A degrees C and length of time from 1 to 5 hours in an airtight chamber with an atmosphere comprising less than 2 per cent of oxygen. The effect of steam-heat treatment on anti-shrink efficiency and anti-swelling efficiency were examined. The results indicated that the dimensional stability of the wood was increased by 73% for heartwood and 71% for sapwood at 230A degrees C for 5 hours, respectively.