Accelerated Mold Test on Dried Pine Sapwood Boards: Impact of Contact Heat Treatment

We test the hypothesis that the combination of kiln drying of double-stacked boards and contact heat treatment will reduce the susceptibility of treated boards to colonization by mold fungi. Winter-felled Scots pine (Pinus sylvestris L.) sapwood boards were double-stacked in an industrial kiln in sapwood out'' and sapwood in'' positions. Dried samples were then contact heat-treated using a hot press at three different temperatures (140 degrees C, 170 degrees C, and 200 degrees C) for three different periods (1, 3, and 10min). An accelerated mold test was performed in a climate chamber where naturally mold-infected samples were used as a source of mold inocula. Contact heat treatment degraded the saccharides that accumulated at dried surfaces, and reduced the mold growth. The threshold temperature and time for inhibiting mold growth were 170 degrees C for 10min. However, for industrial application, the most feasible combination of temperature and time would be 200 degrees C for 3min. We concluded that double stacking/contact heat treatment used is an environmentally friendly alternative to chemicals for reducing mold on Scots pine sapwood boards.