How Wood Shrinks and Swells

The mechanics of shrinkage and swelling and the influence of wood structure are discussed. Structural details of the cell wall are shown, including fibrils, micro-fibrils, and crystallites. One of the prominent things about shrinkage is its variability. Shrinkage not only differs among the three directions of grain–tangential, radial, and longitudinal– but also among species. The shrinkage values of wood based on its dimension when green are given in a table for 43 species of softwoods and 89 species of hardwoods. These values are in percent for radial, tangential, and volumetric and at three levels of moisture content, 20 percent, 6 percent, and 0 percent. The effects of shrinkage and swelling of wood are discussed including warping, casehardening, and strength of wood joints. Methods for minimizing the effects of shrinkage and swelling of wood in service are discussed.

You must be logged in to download any documents. Please login (login accounts are free) or learn how to Become a Member