台灣古蹟福州杉使用百年後之物理性質

Physical Properties over 100-year-old China Fir Wood of Historic Monuments in Taiwan

本研究乃評估台灣傳統建築之老舊福州杉木材使用百年後之物理特性，提供日後木質文物保存之參考。經室外暴露試驗一個月後，老舊福州杉楹材之顏色安定性較健全材為佳。以掃描式電子顯微鏡（SEM）觀察風化表面，結果發現管胞及木質線薄壁細胞已嚴重破壞而喪失其形貌，其中木質線薄壁細胞為弦向組織破壞之起始點；而老舊表面之管胞壁則產生不規則裂縫居多。風化材及老舊材之吸水率（25 ℃ 蒸餾水浸漬24 小時）和徑向厚度膨潤率（40 ℃、90 % 相對濕度下調濕72 小時）均較健全材為高，顯示木材風化及老化作用將影響其尺寸安定性。當木材受腐朽或表面存有老舊彩繪塗料時，尺寸不安定性更甚於風化材及老舊材。 The purpose of this study was to estimate the physical properties of an over 100-year-old China fir wood from aged construction in Taiwanese traditional buildings as a guide for the conservation of wood-based cultural relics. Obviously, the color stability of old china fir purlin wood was better than that of sound one after one-month outdoor exposure. The tracheid and ray parenchyma for weathered woods were severely damaged by SEM observation, it led to a cell appearance loss to some extents, and these checks occurred in the ray parenchyma tissue as their starting points on the tangential surface. On the old purlin woods surface, the irregular slit on tracheid wall was found. The water absorption(%) (specimens dipped into distilled water at 25℃ for 24 hours) and thickness swelling in radial(%) (specimens exposing under 40℃ and 90% R. H. for 72 hours) of weathered wood and old wood were higher than sound wood, and the highest dimensional unstability was obtained when wood specimens decay or containing the polychromes above wood surface.

The purpose of this study was to estimate the physical properties of an over 100-year-old China fir wood from aged construction in Taiwanese traditional buildings as a guide for the conservation of wood-based cultural relics. Obviously, the color stability of old china fir purlin wood was better than that of sound one after one-month outdoor exposure. The tracheid and ray parenchyma for weathered woods were severely damaged by SEM observation, it led to a cell appearance loss to some extents, and these checks occurred in the ray parenchyma tissue as their starting points on the tangential surface. On the old purlin woods surface, the irregular slit on tracheid wall was found. The water absorption(%) (specimens dipped into distilled water at 25℃ for 24 hours) and thickness swelling in radial(%) (specimens exposing under 40℃ and 90% R. H. for 72 hours) of weathered wood and old wood were higher than sound wood, and the highest dimensional unstability was obtained when wood specimens decay or containing the polychromes above wood surface.