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IZVLEČEKV raziskavi smo preučevali količinsko-kakovostni izkoristek bukovine od stoječega drevesa do žaganega lesa. Zanimala nas je ocena kakovosti posameznih dreves in njen vpliv na kakovostne razrede proizvodov iz tega lesa. Pri razvrščanju stoječih dreves smo upoštevali aktualno 5-stopenjsko lestvico ocenjevanja kakovosti Zavoda za gozdove Slovenije (ZGS). Pri ocenjevanju gozdnih sortimentov smo uporabljali standard SIST EN 1316-1:2013, pri ocenjevanju žaganega lesa pa pravila Evropskega združenja žagarske industrije (EOS). Na vzorcu ocenjenih in nato posekanih dreves smo ugotavljali povezave med kakovostjo dreves, iz njih izdelanih sortimentov okroglega lesa in kakovostjo končnih žagarskih izdelkov. V vzorec so bila enakovredno zajeta drevesa vseh petih kakovostnih stopenj. Pri izdelavi gozdnih sortimentov smo dobili največ hlodov B-kakovosti (51 %) in največ žaganega lesa EOS-C-kakovosti (52 %). Iz bukovih dreves odlične kakovosti smo dobili 35 % najkakovostnejših sortimentov in iz teh sortimentov 8 % najkakovostnejšega žaganega lesa. Odločilni kriterij razvrščanja po kakovosti so pri sortimentih okroglega lesa slepice in pri žaganem lesu mrtve in trhle grče.Ključne besede: listavci, bukev, kakovost, napake lesa, žagan les ABSTRACTThe research addresses beech wood, from a standing tree to sawn wood. It focuses on the quality evaluation of individual trees and its impact on the later products made of the respective wood. For the needs of observing the quality of standing trees, the current 5-class scale for quality evaluation of the Slovenia Forest Service (SFS) was used. To evaluate the wood assortment, the SIST EN 1316-1:2013 standard was applied, while the evaluation of sawn wood was performed as per the rules of the European Organisation of the Sawmill Industry (EOS). On the basis of the sample of evaluated and eventually harvested trees, the correlations between the quality of trees, roundwood products made of them and the quality of final sawn products were established. The sample equally included trees of all five quality classes. The production of wood assortment provided the most logs of B quality (51%) and the highest quantity of sawn wood of EOS-C quality (52%). Beech trees of excellent quality provided 35% of the wood assortment of highest quality and these provided 8% of the sawn wood of the highest quality. The key criteria for the classification by quality were covered knots for forest products and dead and unsound knots for sawn wood.Key words: broadleaves, beech, standards, quality, defects in wood, sawn wood (Lipoglavšek, 1994, 1996, Rebula, 2002, Kadunc, 2006, Prka, 2003, Stankić in sod., 2014. Tako se obravnave zgolj gozdarske problematike praviloma končajo na kamionski cesti, kjer se proizvodni proces v gozdu zaključuje. Na istem mestu praviloma opravimo tudi izmero količin, ocenimo kakovost in oddamo sortimente v celoti. Po drugi strani pa se raziskave o kakovosti hlodovine ter količinah in kakovosti proizvodov, izdelanih iz teh hlodov, praviloma začnejo na žagarskem obratu (Šoškić in ...

The analysis evaluates the potential and methods of the respective assessment of beech trees, beech logs and sawn timber. The objective of the study was to assess the impact of the quality of the incoming raw material (tree) on the quality and quantity of products – obtained at the sawmill. The study presents a model that indicates the relations between the assessment of the quality of a standing beech tree and the quality of the sawmill products obtained from its wood. In addition, relations between individual quality classes of sawlogs, pulpwood, energy wood and sawn timber are shown. Standing trees were assessed in three sites according to the national 5-grade quality scale, assortments produced from selected trees pursuant to the EN 1316-1 standard, and sawn timber produced from assortments according to the rules of the European Organisation of the Sawmill Industry (EOS). In total, 87.04 m3 of timber was harvested. In higher quality trees (quality 1 and 2), the shares of sawlogs were between 53% and 72% of gross tree volume, but in the poorest quality trees, the shares were only between 23% and 36%. What remained was pulp and energy wood. In trees of excellent quality (quality 1), sawlogs of the highest quality prevailed (A and B quality grade), while sawlogs of C and B quality prevailed in trees of lower quality. Covered knots and heart defects were typically the decisive criteria for classifying sawlogs quality in all three sites. A total of 30,786 m3 of unedged timber was sawn from the sawlogs, which comprised 35% of the total gross quantity of trees on average. Nine percent of the sawn timber was classified into the A–EOS class (top quality), 27% into the B–EOS class and 47% into the C–EOS class. Seventeen percent of the timber was only suitable for post-processing. The crucial criteria for classifying sawn timber were as follows: dead and rotten knots, heart, curvature and cracks. Above-average sawlogs (A and B quality grade) was mainly obtained from trees of better quality. Relations between the quality of trees, sawlogs and sawn timber indicated the suitability of classifying standing trees and sawlogs, since it was possible to produce sawn timber of higher quality from quality trees or logs. The model presents a rare attempt to establish and monitor quality and quantity from standing tree to end product.

The characterization of the curing process allows the determination of the optimal pressing parameters, which is essential for the economical production of wood-based composites. In this study, an automated bonding evaluation system (ABES), dielectric analysis (DEA), and dynamic mechanical analysis (DMA) were used to determine the curing parameters of biobased pine tannin-hexamine adhesive at five temperatures ranging from 75 to 175 °C. This study aimed to compare the three above methods and to find correlations between them. All methods showed the same trend of the curing process, which became faster with increasing temperature. Due to various heating rates among the different methods, the curves representing the degree of cure were shifted to the left for the period in which nearly isothermal conditions were reached. It was determined that these methods could be mutually comparable. The ABES was regarded as the reference method; the DEA was regarded as a method that overestimates the curing process and that describes the beginning of the curing process more precisely; and the DMA method was regarded as a method that underestimates the curing process and that describes the end of the curing process more precisely. Linear trend lines were found between the observed methods.

The performance of the composites is influenced by the service life of input raw wood material and used adhesives. The aim of the study was to assess the durability and mechanical performance of glulam beams treated in a different way (thermally modified and/or treated with copper-based wood preservative) and exposed in an outdoor application. Glulam beams (83 mm × 68 mm × 1100 mm), made of three layers of Norway spruce (Picea abies) with PUR adhesives used have been exposed in use class 3.2 in a horizontal position since 4th November 2016. Part of the specimens was equipped with MC sensors. Every year, the degradation was evaluated visually. The dynamic modulus of elasticity was determined by longitudinal vibration, and the static modulus of elasticity using a 4-point bending test. On the smaller specimens, cut from glulams, compressive strength, delamination, and shear strength of adhesive bonds were determined. After two years of exposure, the results indicate that the performance of glulams is determined by the wood modification and applied wood preservative.