Cupping in Seasoned Boards from Plantation Softwood Thinnings

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Balodis, V.



12 p.

Cupping in air seasoned commercial boards at a given distance from the pith is more severe for species which exhibit large difference between tangential and radial shrinkage. In this survey, the largest cupping values were observed in back-sawn boards cut from Pinus elliottii and P. taeda and the least for Araucaria cunninghamii. Within stems, cupping decreases with increasing distance from board to the pith. For practical purposes even for the Pinus species cupping becomes neghgible for backsawn boards if the perpendicular distance from the face of the board to the pith exceeds 6 cm. The effect of moisture content, and the effect of transverse shrinkages on cupping, were investigated in short P. elliottii experimental boards dried without external restraint. For moisture content below 20%, cupping was linearly related to moisture content. Two mathematical models for the prediction of cupping were formulated and the estimated values of cupping compared with the observed values. The more successful of the two models was that based on the assumption that elements within a cross-section of a board are free to move relative to each other.



CSIRO. Division of Forest Products; Division of Forest Products Technological Paper; Forestry and Forest Products; Thinning (Trees); Timber; Timber seasoning

This report has been placed on the CSIRO repository and may be made available to persons outside of CSIRO for non commercial purposes, in its entirety and without deletion of disclaimers and copyright information.

Published Version (pdf) (18.41MB)

Division of Forest Products Technological Paper

no. 63



Balodis, V. Cupping in Seasoned Boards from Plantation Softwood Thinnings. Melbourne: CSIRO; 1972.

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