EFFECT OF PRESTREAMING ON DRYING STRESSES OF RED OAK USING A COATING AND BENDING METHOD

This study was initiated to investigate the effect of presteaming on d rying stresses of red oak (Quercus sp.) using the coating and bending method. Besides the presteaming effect, a directional effect on drying stresses was also tested. Four blocks were randomly selected. Each bl ock was divided into two pairs (four samples). One pair was randomly a ssigned to steaming while the other was assigned to control. A statist ical split-plot model was used to anlayze the results. Presteaming inc reased drying stress by up to 36% and decreased drying time by 23% whe n red oak was dried at 75% relative humidity and 44 C from average moi sture content of 80 to 16%. The maximum drying stress of the steamed s amples occurred before that of the unsteamed samples due to faster moi sture loss from the sample. This study indicated that the coating and bending method could be used to study drying stresses of red oak. The statistical model revealed the differences between steaming and contro l and between inner and outer directions. Drying stresses were differe nt in two opposite directions (outward and inward), regardless of whet her the wood was steamed or not.