Proceedings e report - Firenze University Press

METHODS OF NON-DESTRUCTIVE WOOD TESTING
Peter Niemz*
ETH Zurich, Institute for Building Materials (Wood Physics)
CH 8093 Zürich, Schafmattstrasse 6, HIF E25.2
Abstract
Methods of non-destructive wood testing are getting more and more important. Online tools, for example to
control the production, are effectually in use for years. Based on a measuring systematic (physically active
principle and important influencing factors), a summary of methods to assess cultural goods is given in the
following. To adopt the methods based on physical effects, essential knowledge of wood physics is inevitable
(knowledge of interdependencies, in particular).
1. Introduction
Methods of non-destructive wood testing are getting more and more important. Online tools, for
example to control the production, have been in use for years. These tools can detect cracks in boards
and their size (measured via ultrasound), density perpendicular to the board plane and surface
irregularities. Chromatometers, gauges for thickness measurement, ultrasonic tests (including
computed tomography), X-ray equipment, equipment to analyse chemical structures as well as NIR
spectroscopy equipment are available. Optical systems can be used to detect strain concentrations that
occur due to humidity changes. Based on a systematic of physically active principles and important
influencing factors, a summary of methods to assess cultural goods is given in the following. To adopt
methods based on the consideration of physical effects, an essential knowledge of the underlying
wood physics is required, in particular knowledge of interdependencies.
2. Short overview of commonly appplied methods
Table 1 (at the end of the paper) gives an overview of available methods for non-destructive wood
testing.
2.1. X-ray tomography (detection of internal defects):
Fig.1 and 2 show an X-ray tomography from spruce with knots at different distance from the surface.
* E-mail: niemzp@ethz.ch
Fig. 1. X-ray tomography of spruce with knots
Joseph Gril (edited by), Wood Science for Conservation of Cultural Heritage –Braga 2008: Proceedings of the International
Conference held by COST Action IE0601 (Braga - Portugal, 5-7 November 2008, ISBN 978-88-6453-157-1 (print)
ISBN 978-88-6453-165-6 (online) © 2010 Firenze University Press