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Effect of high-temperature drying and restraint on twist of Norway spruce

Frühwald, Eva LU (2007) In Drying Technology 25(1-3). p.489-496
Abstract
During drying, timber distortion is a major defect mainly due to shrinkage anisotropy, differences in longitudinal shrinkage, and spiral grain. The distortion can be reduced by external restraint and use of appropriate kiln schedules. The research presented here is part of a project on the improvement of shape stability of Norway spruce by high-temperature drying. The effects of drying temperatures between 80 and 170 degrees C and restraint on the extent of twist in Norway spruce were investigated on 30 cm lengths. Results show that significant twist reduction could be achieved in restrained specimens sawn from core wood. This effect was permanent even after exposure to subsequent moisture cycling. In addition to high-temperature drying,... (More)
During drying, timber distortion is a major defect mainly due to shrinkage anisotropy, differences in longitudinal shrinkage, and spiral grain. The distortion can be reduced by external restraint and use of appropriate kiln schedules. The research presented here is part of a project on the improvement of shape stability of Norway spruce by high-temperature drying. The effects of drying temperatures between 80 and 170 degrees C and restraint on the extent of twist in Norway spruce were investigated on 30 cm lengths. Results show that significant twist reduction could be achieved in restrained specimens sawn from core wood. This effect was permanent even after exposure to subsequent moisture cycling. In addition to high-temperature drying, heat-treated material (Thermowood (R)) was also investigated. As for the high-temperature dried material, twist amplitude in moisture cycling was highest for pith-in specimens. Increased heat-treatment temperature reduced the twist amplitude, thus improving the shape stability. However, for the material dried in this study, shape stability was not influenced by the drying temperature. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Norway spruce, high-temperature drying, thermowood, shape stability, twist, restraint, KSTRWood
in
Drying Technology
volume
25
issue
1-3
pages
489 - 496
publisher
TAPPI
external identifiers
  • wos:000245315200068
  • scopus:33847796477
ISSN
1532-2300
DOI
10.1080/07373930601184056
language
English
LU publication?
yes
id
5cdefb18-21fe-45c7-af3f-95a52188acfd (old id 668550)
date added to LUP
2007-12-11 14:31:50
date last changed
2017-01-01 04:48:57
@article{5cdefb18-21fe-45c7-af3f-95a52188acfd,
  abstract     = {During drying, timber distortion is a major defect mainly due to shrinkage anisotropy, differences in longitudinal shrinkage, and spiral grain. The distortion can be reduced by external restraint and use of appropriate kiln schedules. The research presented here is part of a project on the improvement of shape stability of Norway spruce by high-temperature drying. The effects of drying temperatures between 80 and 170 degrees C and restraint on the extent of twist in Norway spruce were investigated on 30 cm lengths. Results show that significant twist reduction could be achieved in restrained specimens sawn from core wood. This effect was permanent even after exposure to subsequent moisture cycling. In addition to high-temperature drying, heat-treated material (Thermowood (R)) was also investigated. As for the high-temperature dried material, twist amplitude in moisture cycling was highest for pith-in specimens. Increased heat-treatment temperature reduced the twist amplitude, thus improving the shape stability. However, for the material dried in this study, shape stability was not influenced by the drying temperature.},
  author       = {Frühwald, Eva},
  issn         = {1532-2300},
  keyword      = {Norway spruce,high-temperature drying,thermowood,shape stability,twist,restraint,KSTRWood},
  language     = {eng},
  number       = {1-3},
  pages        = {489--496},
  publisher    = {TAPPI},
  series       = {Drying Technology},
  title        = {Effect of high-temperature drying and restraint on twist of Norway spruce},
  url          = {http://dx.doi.org/10.1080/07373930601184056},
  volume       = {25},
  year         = {2007},
}