This project investigated the suitability of superheated steam/vacuum (SS/V) drying for tamarack (Larix laricina) with emphasis on colour change and rot-resistance. SS/V drying was used on 5/4-inch and 7/4-inch lumber and the results were compared to three conventional drying schedules: high temperature (115oC), elevated temperature (90oC), and standard temperature (82oC).
All the drying processes tested did not affect the rot-resistance of tamarack, however, they had varying effects on colour. High-temperature drying resulted in the greatest post-drying colour change. The SS/V process resulted in almost no colour change. Compared to current industry practices, drying by SS/V is approximately 2.6 to 3.1 times faster and there was better warping control for the 7/4” test. Superheated steam/vacuum drying appears to offer good potential for drying value-added wood products.