Beech (Fagus sylvaticaL.) – Technological properties, adhesion behaviour and colour stability with and without coatings of the red heartwood

Abstract

-European beech (Fagus sylvatica L.) is a popular and major tree species in Europe. The economic value of its timber is greatly decreased by the red heart phenomenon. The cause of red heart formation is well understood. However, scientific investigations about the technological and mechanical behaviour of red heartwood are scarce. Our study aims to provide a sound scientific basis for the characterization of technological properties, adhesion-as well as colour-behaviour of red-hearted beech. The mechanical and technological properties of redhearted beech give no evidence of different behaviour in comparison with the normal beech wood. The adhesion behaviour shows equal results. In terms of colour stability, the difference between freshly processed normal and red beech wood diminishes after certain time of exposure. red heart / adhesion behaviour / colour stability / mechanical technological property / Fagus sylvatica Résumé -Le bois de hêtre (Fagus sylvatica L.) -Propriétés technologiques, comportement au collage et stabilité de la teinte du bois de coeur rouge. Le hêtre (Fagus sylvatica L.) est une espèce d'arbre populaire important en Europe. La présence du coeur rouge provoque une réduction notable de la valeur économique des grumes qui en sont atteintes. Les causes de l'apparition du coeur rouge sont bien connues mais les études scientifiques sur le comportement technologique et mécanique du hêtre à coeur rouge sont cependant rares. La présente étude a pour but d'établir des bases solides pour la caractérisation des propriétés technologiques du hêtre à coeur rouge que sont le comportement au collage et la stabilité de teinte. Il n'existe aucun indice selon lequel les propriétés technologiques et mécaniques du hêtre à coeur rouge diffèrent de celle du hêtre normal. Pour ce qui est du comportement au collage, les résultats sont identiques alors que pour la stabilité de la teinte la différence à l'état frais de sciage entre le hêtre normal et le hêtre à coeur rouge diminue après un certain temps d'exposition. coeur rouge / comportement au collage / stabilité de teinte / propriété technologique et mécanique / Fagus sylvatica

Content of Total Phenols in Red Heart and Wound-Associated Wood in Beech (Fagus sylvatica L.)

“…The economic importance of beech has increased in recent years because of the continuous demand for bright and evenly colored grades of logs and sawn timber (Pöhler et al, 2006). However, the occurrence of red heart amongst older trees and the consequences of mechanical wounding to the lower parts of stems, which occurs during forestry operations in unevenly managed forests, decrease wood quality and even increase timber loss.…”

“…However, the occurrence of red heart amongst older trees and the consequences of mechanical wounding to the lower parts of stems, which occurs during forestry operations in unevenly managed forests, decrease wood quality and even increase timber loss. Discolored beech wood has a lower value on the market today than unaffected wood, due to its unfavorable technological properties, including hard impregnation, problems in drying processes and veneer production and, fi nally, its esthetic defi ciency (Koch et al, 2000;Pöhler et al, 2006).…”

Quantitative HPLC Analysis of Catechin in Wound- Associated Wood and Knots of Beech

“…One of the main deficiencies of this tree species is its tendency to develop discolored wood in the central part of the tree, often called red heart, red heartwood, facultatively colored heartwood, false heartwood or red core (Bosshard, 1974;Torelli, 1984;Shigo, 1986;Sachsse, 1991;Wernsdörfer et al, 2005). As opposed to normal wood, discolored beech wood is characterized by its unfavorable technological properties, including hard impregnation, problems in drying processes and veneer production and esthetic insufficiency (Koch et al, 2000;Pöhler et al, 2006). In addition, wood of trees from unevenly managed forests is regularly subjected to mechanical wounding, which results in a relatively predictable response of the tree.…”

Influence of wood properties and bonding parameters on bond durability of European Beech (Fagus sylvatica L.) glulams

“…Studies on the short-term strength of defect-free, standardised specimens have revealed a variety of suitable adhesive types. These tests have shown that the short-term strength of test specimens, unaged prior to testing, was not affected sufficiently by adhesive type, amount of red heartwood (a species-inherent discoloration) or steaming level of the lamellae (Frühwald et al, 2003;Ohnesorge et al, 2006;Pöhler et al, 2006). Indeed, the longitudinal tensile shear strength tests carried out on structural adhesives before their approval and classification (EN 301:2006) must be conducted using beech timber.…”

“…al., 2006Ohnesorge et. al., , 2008Pöhler et al, 2006). The investigations conducted by Glos and Lederer (2000) and Blaß et al (2005), which form the basis of the impending gen-* Corresponding author: institut@fobawi.uni-freiburg.de eral building approval guidelines by the German Institute of Civil Engineering in Berlin (Z-9.1-679, Deutsches Institut für Bautechnik, 2009), in particular, have recommended beech glulam beams as a reliable, versatile construction product for use in moderate climates specified as service class I according to EN 1995EN -1-1:2004 One major challenge is to ensure that beech glulam bond integrity, especially bond durability, is adequate.…”