Y. Ito et al., COMPRESSIVE-MOLDING OF WOOD BY HIGH-PRESSURE STEAM-TREATMENT - PART 1- DEVELOPMENT OF COMPRESSIVELY MOLDED SQUARES FROM THINNINGS, Holzforschung, 52(2), 1998, pp. 211-216
We attempted to compressive-mold logs of sugi (Cryptomeria japonica D.
Don) to squares, and to permanently fix the transformed shape. The tra
nsformation and fixation were successively conducted under high-temper
ature saturated steam atmosphere by a newly designed apparatus which w
as a combined pressure vessel and a press machine. The results are sum
marized as follows: (1) The logs were successively softened by steamin
g at 150 degrees C, compressively molded to square, and fixed the tran
sformed shape by steaming at 200 degrees C in this apparatus. (2) The
shape of square fixed by high-pressure steam-treatment did not recover
to original log shape by water-soaking and boiling. The result shows
that the high-pressure steaming is effective for permanent fixation of
the transformed shape. (3) The condition for sufficient fixation of t
he compressive transformation was steaming at 200 degrees C for 3 min
when a 15 cm of diameter and 10 cm of length sugi-thinning was used as
a specimen. (4) Inner stress within a compressed wood was gradually r
educed during steaming and, finally, the stress was removed completely
.