Influence of Duration of the Conditioning Process on the Reduction of Case-Hardening Level in Kiln-Dried Beech and Oak Lumber

Abstract

The research results from an analysis of the influence of conditioning time on case-hardening reduction are presented. The levels of case-hardening and moisture content differences across the thickness on beech and oak lumber were measured before, during, and after conditioning. A relationship between gap, as the measure of case-hardening in wood (ENV 14464), and conditioning time was found; a highly linear relationship also exists between gap and moisture content differences across the lumber thickness. Time analysis showed that much shorter conditioning times were adequate to reach acceptable drying quality than the times currently used. It is shown that the conditioning regimes that use equilibrium moisture content lower than the final moisture content are inadequate to obtain a dried product quality that meets modern European standards.