Impact of continuous drying method on drying quality of southern pine sawn timber

Abstract

The continuous drying of timber is attracting increasing international interest for softwood drying because of several reported advantages, e.g., improved energy efficiency and improved grade recovery. This study aimed to investigate the impact of continuous drying kiln technology on the quality of dried Queensland plantation-grown southern pine timber, compared to the current ultra-high temperature batch drying process adopted by many softwood processors. End matched boards were dried using continuous and high-temperature drying schedules. The moisture content and moisture gradient of each board was assessed in accordance with AS/NZS standard 1080.1 (2012), AS/NZS standard 2796.3 (1999), respectively, while the drying stress was assessed in accordance with AS/NZS standard 4787 (2001). The boards dried with continuous drying schedules resulted in slightly lower bow and spring values and similar cup and twist values compared to the high temperature dried boards. The moisture gradient and drying stress were significantly lower in boards using continuous drying kiln technology compared to the high temperature dried boards. This study will allow the Australian softwood industry to better understand the dried timber quality obtained using new continuous drying technology to make informed investment decisions.