IMPORTANT NOTE

This web page is part of a web site that is no longer actively maintained by anybody at ANU SRES. It has been left on the web due to its apparent popularity (every time we've removed it, people have complained within 24 hours), but is presented AS IS - attempting to contact any individual named on the page is likely to fail, and the SRES webmaster doesn't want to hear about such failures or entertain any communication about updating of the page's contents. You have been warned.

ANU Logo

Warpage of Timber

Warpage is the distortion of boards causing a departure from its original plane developed as a result of uneven shrinkage (Rosen 1987). General kinds of warp are defined as follows;

  • Cup - The distortion of a board in which there is deviation flatwise from the straight line across the width of the board.

    Twist,Spring & Bow

    Board Distortion (Pratt 1974)

  • Bow - The distortion in a board that deviates from flatness lengthwise but not across its face.

  • Crook - A distortion of a board in which there is deviation edgewise from a straight line from end to end of a board.

  • Twist - A distortion caused by a turning or winding of the edges of a board so that the four corners of any face are no longer in the same plane.

  • Kink - Usually an edgewise deviation caused by a knot or severe localised grain distortion to develop two straight portions in the piece at a large obtuse angle.

Characteristic shrinkage as effected by growth rings

Characteristic shrinkage and distortion of flats, squares and rounds as effected by the direction of annual growth rings. (Mills 1991).


Back to Drying