REDUCTION OF EFFECT OF GROWTH STRESS PRESENCE USING ENDLESS SCREW DURING KILN DRYING AND STEAMING AND HEATING TREATMENT IN LOG BEFORE SAWING

The relaxation of growth stress in trees growing in fast-growth conditions, as plantation in tropical areas, affects lumber quality during of sawing or drying process. It was evaluated two pretreatments (heating and steaming application) before sawing process and endless screw use to maintain the boards pressed during drying of Dipteryx panamensis and Hieronyma alchorneoides wood with objective to reduce the effects of relaxation of growth stress. The results showed endless screw is used to maintain the boards pressed, the moisture content (MC) or drying rate did not vary. The use of endless screws with daily adjustment during drying produced a reduction of cup, check and split defects in lumber and this treatment is accompanied with a pre-treatment before sawing (heating or steaming treatment) decreased the incidence of drying defects. Then the use of both treatments is an opportunity to reduce the effects of relaxation of growth stress on the quality of the wood of D. panamensis and H. alchorneoides from fast-growth plantation conditions.