EFFECT OF HEAT TREATMENT UPON DIMENSIONAL STABILITY AND MASS LOSS OF BLACK PINE AND SPRUCE WOOD ORIGINATING FROM MATURE TREES VS. THINNINGS

The paper presents the results of anexperimental study performed with black pine (Pinusnigra L.) and spruce (Picea abies L.) wood, originatingfrom mature trees and thinnings cut from the sameparcel from the Stroesti-Arges region in Romania.After air drying and conditioning, the defect-freeboards were cut into standard samples 30x20x20mm.These were first dried to oven-dry state, then heattreatedat high temperatures (180 and 200oC) for 1, 2,3 and 4 hours. Weightings before and after heattreatmentallowed establishing the mass loss. Thetotal linear and volumic swelling coefficients were alsodetermined both for the heat-treated and untreatedsamples, in order to establish the effect of the heattreatmentupon the dimensional stability. The resultswere comparatively analyzed for the two species (pineand spruce), for the two grades (mature and thinwood), in order to establish for each the optimumtreating conditions, namely the ones which allow forthe maximum improvement of the dimensionalstability, without affecting significantly the wood mass(and implicitely the mechanical strengths). The resultsof the present research are to be valorized at themanufacturing of solid wood panels made from heattreatedlamellas