Effect of Log Heat Treatment on Release of Growth Stresses in Eucalyptus Nitens

Abstract

The use of Eucalyptus nitens has diversified the Chilean lumber industry in unprecedented ways. However, growth-induced strains cause splitting and warping. The objective of this investigation was to determine the effect of the heat treatment applied to logs of Eucalyptus nitens on the reduction of growth stresses and improvement of quality in sawn wood. Logs were extracted at different heights of the tree for 15-yr and 20yr-old tress. The sawmill process was allowed to obtain radial, mixed, and tangential plane pieces, at two thicknesses (25 and 50 mm). The evaluation of MC and warping was according to Chilean National Standards. The results obtained in this research suggest that by applying the heat treatment to Eucalyptus nitens logs, a significant reduction in growth strains can be achieved. Heat treatment also increased the quality of the pieces in terms of bow, crooking, and twisting. Therefore, there are substantial benefits of using heat treatments to reduce defects caused by growth strains and thus increase the quality of the wood and reduce its warp.

Investigating Storage Time to Minimize End-Splitting in Eucalyptus Nitens Logs

“…This becomes relevant for Eucalyptus nitens, as it is prone to a large amount of end-splitting after harvest (Washusen et al 2009). In this context, Vega et al (2016) and Rozas et al (2021aRozas et al ( , 2021b; observed significant differences in Eucalyptus nitens and significant end-splitting at different time intervals. Similar behavior was observed by other researchers, Franc ¸a ( 2014) reported severe end-splitting from 7 d, Hillis and Brown (1978) reported it on 6 d, and Bariska (1990) on 5 d. However, Lima et al (2002) reported that end-splitting reached its maximum between harvest and 3 d.…”

“…The interest in using fast-growing species in the wood industry has allowed foresters to position the different species of Eucalyptus, as alternative raw materials for the primary conversion industry, mainly due to their high capacity to adapt to different forest sites (Cardoso et al 2005;Lima 2005;Gonc ¸alves et al 2006;Franc ¸a 2014;Rozas et al 2021aRozas et al , 2021b. The main use of fast-grown Eucalyptus species is for pulp and paper production (Balasso et al 2022).…”

“…However, the genus Eucalyptus has high growth stresses, which limits the potential for obtaining production of higher value-added products (Gonc ¸alves et al 2006;Souza 2006;Trugilho et al 2006;Lima et al 2007;Trugilho et al 2007;Biechele et al 2008;Monteiro et al 2010;Valencia et al 2011;Trevisan et al 2013;Cunha et al 2015;Rozas 2015;Vega et al 2016;Rozas et al 2021aRozas et al , 2021b. Growth stresses take the form of end-splitting after harvest and warping during mechanical processing, drying, and use when construction, reducing the yield and quality of wood products (Matos et al 2003;Rozas 2015;Vega et al 2016;Schmidt et al 2019).…”

Distribution of Growth Stresses in Eucalyptus nitens Maiden Logs Immersed in Water

“…Several methods to reduce growth stresses have been used; however, none of them have been considered entirely satisfactory [11]. Among the methods used to release growth stresses are the use of metal or plastic straps [12], gang nail-type metal connectors and S-or C-shaped hooks [13], chainsaw banding, and the drying technique applied to the standing tree [9,14], the application of temperature (water or steam) to logs [14][15][16][17][18], and different cutting directions such as the radial and tangential cuts of two symmetrical sides [19][20][21][22].…”