The objective of this report is to review published research and provide an overview of the available technology for improving the properties of OSB. Computer searches were made of Agricola, Chemical Abstracts, CAB Abstracts, PCForest and TreeCD. In addition, lists of reports were requested from research groups known to have worked in the area. This report deals first with alternative treatment processes and their effects on the physical properties of the board and second with the performance of the treated products. The second section discusses only those treatments which had acceptable effects on board properties. In terms of practicality, economics and optimum physical properties of the finished board, the best treatments appear to be powder or concentrated liquid additives at the blender using certain combinations of preservative and adhesive. Borates are effective for protection against decay and termites in applications protected from the weather such as sheathing. As yet, no treatment has been developed which will provide long-term performance in ground contact. For fire retardant performance vapor boron treatment of the finished panel may be the best option. Further work is required on processes to improve dimensional stability of OSB.
A 2-D heat and mass transfer finite element model based on the water potential concept was previously developed to simulate the evolution of moisture content and temperature in the cross section of a piece of lumber during drying. In order to be able to use the model with an industrial interest, an user interface was developed and the experimental parameters required for the model were determined for three Eastern softwood commercial species within the project no. 2674 Drytek Enhancement for Commercial Species. The user interface was developed using the MatLab development environment. It generates the mean drying and wood temperature curves, computes the maximum effective moisture content gradient and shows the evolution of the 2-D moisture content and temperature profiles during drying. The pressure membrane technique and equilibration over saturated salt solutions were used to determine the moisture content–water potential relationship at 30, 60 and 90oC for balsam fir sapwood and heartwood, black spruce heartwood and jack pine heartwood, in desorption from green to dry conditions. The instantaneous profile method was used to determine the effective water conductivity of the same species from 30 to 90oC in the three main directions: radial, tangential and longitudinal. Experimental determination of the parameters was initiated for white spruce sapwood and heartwood and will be available in a near future. Kiln drying tests of black spruce and balsam fir were performed in order to validate simulation results.
The Canadian lumber industry has identified, as a high priority, the establishment of a multi-year Lumber Properties Program that pulls together a number of urgent initiatives currently underway to establish and/or maintain Canadian lumber design values. The desire is to have an overall program that emphasizes the proper development of a longer-term strategic plan and process to deal with current and future initiatives. Combining the current industry resources with Federal Government contributions through Natural Resources Canada (NRCan), the first step in the Program has been completed: to gather the various initiatives now underway and to begin the formal development of pan-Canadian policies to guide the development, implementation and on-going maintenance of such initiatives.
The key activities in 2006-07 were:
Launching of the pilot phase of the on-going monitoring program, and development of a simulation model to assist in determining what sort of trends can be reliably detected and which cannot;
Completion of the in-grade testing program on Canadian Norway spruce;
Analysis of the No.2 2x4 Hem-Fir (N) monitoring study and confirmation of the appropriateness of assigned design values;
Identification of an alternative species grouping procedure for further study;
Starting of a process under the ASTM Committee on Wood to address gaps in the Grade Quality Index provisions in ASTM Practice D1990, and
Establishing a forum for engaging the US in discussions on lumber properties issues.
Lumber properties issues crucial to maintaining the competitiveness of Canadian lumber continue to be the same as in previous years: tests and means to adjust for sample representativeness using the Grade Quality Index (GQI), species grouping and re-grouping procedures, and on-going lumber monitoring. As a result, discussion on a pan-Canadian strategy and supporting policies necessary to support Canadian lumber initiatives tend to focus on these three issues. The challenge is to ensure that these issues are dealt with in a way that balances both short and longer-term needs and provides a net overall benefit to the Canadian industry.
Around the world natural durability is classified in different ways. The nature and rigor of the tests used to measure durability, the method of classification based on these data, and use of these classifications to specify end uses or predict service life all vary. This can lead to confusion among people not familiar with the various systems used. This review describes the methods used to classify naturally durable wood around the world.
La détermination de la teneur en humidité du bois est un facteur clé lors de toutes les étapes de transformation afin d’obtenir des produits de qualité, diminuer les pertes de matière première et minimiser les problèmes lors de l’utilisation finale. L’objectif de ce projet est de développer des procédures d’évaluation de la teneur en humidité des bois d’apparence pour les différentes étapes de transformation, soit de l’usine de sciage au séchoir, du séchoir à l’entrée de l’usine de transformation, en cours de transformation et de l’usine de transformation aux utilisateurs finaux.
L’utilisation de procédures d’évaluation de la teneur en humidité fiables, reconnues et éprouvées sera bénéfique aux manufacturiers et leurs relations d’affaires. Les relations entre les clients et les fournisseurs (internes ou externes) reposent sur la confiance mutuelle et la mesure de la teneur en humidité est une des principales causes de mésentente. De plus, une mauvaise évaluation de la teneur en humidité sur les produits semi-finis ou finis a des conséquences coûteuses pour les entreprises.
Une partie de ce rapport est consacrée aux notions de base car il est primordial de comprendre certaines propriétés physiques du bois pour interpréter des mesures de teneur en humidité, Parmi celles-ci, notons l’humidité dans le bois, la teneur en humidité d’équilibre, le gradient de teneur en humidité et le point de saturation des fibres. Il est aussi essentiel de connaître la relation entre les variations de la teneur en humidité du bois et la stabilité dimensionnelle des produits en bois, soit les notions de retrait et de gonflement.
Une autre partie décrit les trois (3) principales méthodes de détermination de la teneur en humidité, soit la méthode au four, par humidimètre à résistance et par humidimètre diélectrique et explique les différents facteurs qui affectent ces méthodes. Des procédures de base pour chaque méthode sont présentées et aussi adaptées pour tenir compte de l’état du bois (vert ou sec, brut ou raboté, empilé ou non, sur lattes ou solide, etc.) et de l’étape de production (usine de lattage, séchoirs, entrée de l’usine de transformation, réception de camion, produits finis, etc.). En dernier lieu, les notions de base de statistiques et d’échantillonnage sont abordées sommairement.
In April 2008, the State of California adopted an airborne toxic control measure (ATCM) to reduce formaldehyde emissions from composite wood products, proposed by the California Air Resources Board (CARB), part of the California Environmental Protection Agency. Phase 1 started in January 2009, and at the end of the implementation, in July 2012, formaldehyde emission limits will range between 0.05 and 0.13 ppm, depending on the type of products, based on the ASTM E 1333 Large Chamber Method.
These new limits are in the order of the limits of detection of the current analytical methods presently used, and rendered the chromotropic acid reaction, on which the ASTM E 1333 is based, with a limit of detection of 0.01 ppm less precise.
An alternative method to determine formaldehyde concentration in air has been developed to be used as part of the ASTM E1333 Large Chamber Method. 60 L of air are sampled through an impinger containing an acetylacetone-ammonia solution. The solution is then heated, and analyzed by fluorimetry using a Turner Quantech filter fluorometer equipped with a NB430 excitation filter and a SC500 emission filter. The test method is inexpensive, easy to use, compatible with the Large Chamber, Perforator and Desiccator Methods, and is very sensitive. The minimum detection limit (MDL) and the limit of quantification (LOQ) of this analytical method are 0.0004 and 0.0013 ppm, respectively.
