In this report, a comprehensive literature review on wood hardening has been conducted. In addition, a Japanese wood densification method that uses compression and RF heating has been applied to densify Aspen lumber from Alberta. The main conclusions are:
1. Wood can be densified through compression under heat as evidenced by the Japanese compression method.
2. The densified Aspen lumber can be as hard and strong as known hardwoods such as Oak and Beech. Problems, however, exist: arcing associated with RF heating, property variation associated with arcing and micro fracturing, also dimensional fixation.
3. Wood can also be densified and hardened by resin impregnation. This approach has been extensively covered by a literature review including a number of recent patents.
4. The Induriteä process can also be considered as an impregnation process, which has been commercialized in New Zealand and claimed to be environmentally sound.
5. Very little work has been done on the densification and hardening of Aspen, an important wood species in the province of Alberta.
Based on the results of this study, an approach of combining the advantages of both wood densification using conventional heating and resin impregnation is recommended to be explored for the hardening of Alberta wood species, particularly Aspen. Reasons for the recommendation are given in this report.