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

Abstract

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 ofDipteryx panamensisand Hieronyma alchorneoideswood with objective to reduce the effects of relaxation of growth stress. Theresults 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 theincidence of drying defects. Then the use of both treatments is an opportunity to reduce theeffects of relaxation of growth stress on the quality of the wood of D. panamensisand H.alchorneoidesfrom fast-growth plantation conditions.