Tuesday - Friday | August 25-28, 2020

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IWF Education: Drying/Manufacturing Defects

23. April 2020 09:47

By: Denny Hickman, Allegheny Mountain Hardwood Flooring President

How lumber is dried is one of the most important aspects of how a wood floor performs.  The process used depends on the thickness, species, and cut of the material.

Wood changes dimensions below the fiber saturation point when it gains or loses moisture.  It also shrinks and swells differently in each direction.  Wood shrinks and swells the most circumferentially around the growth rings (tangentially), about half as much across the rings (radially), and only in miniscule amounts along the grain (longitudinally).  For this reason, the different cuts of wood – plainsawn, riftsawn, quartersawn, and livesawn – each require different drying methods.

If plainsawn boards and rift and quartered boards are all dried in a kiln together, the boards will not be dried equally or correctly.  The result is that they will end up with different moisture content levels, which will impact performance and cause wood to become distorted.

Understanding how different cuts of lumber should be dried, and how moisture will affect each type of cut, will help you understand how the floor will look and perform in the long run.  It also will help you to identify different drying or manufacturing defects, determine their causes, and implement their cures.

Learn more on this subject and other wood floor related topics during the "Wood Flooring Symposium" presented by the NWFA - National Wood Flooring Association at IWF 2020.