A comparison between cold water and steam for SPF lumber conditioning

Abstract

Conditioning is an effective method to release drying stresses and improve final moisture content (MC) distribution for spruce-pine-subalpine fir (SPF) lumber during drying. There are currently two methods used in the industry to add moisture to lumber during conditioning, namely low-pressure steam spray and cold water spray. Sixteen kiln drying runs were carried out in a laboratory kiln. Two types of conditioning treatment were investigated: cold water spray and steam spray. Temperature profiles, final MC distribution and drying stresses obtained for lumber conditioned by the two methods were evaluated and then compared. Results indicated that there were no significant differences on drying temperature profiles and lumber quality between the two humidification systems. Therefore, both humidification systems can be used for controlling humidity during kiln drying and for conditioning treatments.