Wood Quality Services
Understanding the extent to which site, the environment and genetic variables impact upon the quality of paper produced is important to optimise the selection of forest resources with desirable fibre characteristics. FFP uses a suite of “rapid screening” techniques to assess the wood properties of the raw material; these tools include light microscopy combined with image analysis (for wood anatomical properties), gamma ray densitometry (for wood density) and near infra-red spectroscopy (for wood chemical properties).
The purpose of rapid wood screening is:
For the evaluation of commercial timber by relating wood properties to the characteristics of the end product (e.g. pulp strength properties)
To support the early prediction of the wood qualities from a non-destructive sample for the tree breeders
How does wood screening operate?
The process followed is:
Measure wood properties at different positions from pith to bark, and at different heights (for different genotypes, sites, ages, etc.) to capture variability
Generate profiles of wood properties within each tree (or compartment) from these measurements
Develop models to predict wood properties of the whole tree from a bark-to-pith core.
Correlate the predicted wood properties with the characteristics of the desired end product.
Use the correlations to predict end product quality from sample bark-to-pith cores of a particular compartment; or to screen a set of compartments to find those with the most appropriate properties.
- Near-Infrared Absorption (NIRA) Spectroscopy
- Image analysis
Image analysis is a screening tool which makes use of a Leitz DM RBE research microscope with fluorescence light, video camera and image analysis software. Images are obtained microscopically from a section of wood and these images are transformed in such a way that they can be automatically analyzed by measuring required features (fibre diameter, fibre wall thickness, vessel frequency).
The benefits of using image analysis are:
- Automation and standardization of the measurement procedure,
- Increased accuracy of the measurement
- Automatic evaluation of results
Gamma Ray Densitometry
Rapid and detailed assessment of wood, to determine density profiles of trees from pith to bark and between different heights of the tree, is made possible by use of radiation densitometry. The basic principle is that an incident beam of gamma-rays is collimated onto a wood specimen. Part of the beam is scattered or absorbed by the sample material. The beam of the photons passing unchanged through the sample is counted by a detector. The difference in intensity between incident and emergent beams can be transformed to give a density value for the absorber.
Near-Infrared Absorption (NIRA) Spectroscopy
NIR reflectance spectra are acquired using a NIRSystems Inc. Model 6500 near-infrared spectrometer or an XDS NIR spectrometer. Spectra obtained from the reflection of near-infrared radiation from either sawdust or solid wood samples can be calibrated against laboratory-determined measurements of pulp yield, lignin, hemicelluloses, cellulose, etc. Models developed based on this approach allow prediction of pulp yield and the relative amounts of wood components to be determined without need for additional laboratory analyses.
Our chemical laboratory is equipped to measure the chemical composition of different wood species for components such as cellulose, lignin, hemicellulose and extractives content.
The MORFI Compact Fiber Analyser provides high resolution analysis of pulp fibre and shives. Analysis includes length, width, curl, kink and coarseness of the fibre, as well as shives and fines analysis. The Morfi can measure thousands of fibres quickly with high accuracy with no need of special sample preparation.
For more information on Wood Properties, please contact